From 2b4bc409f75c07f81d62c014e10ed82366d58e32 Mon Sep 17 00:00:00 2001
From: David Gustavsson <david.e.gustavsson@gmail.com>
Date: Fri, 14 Jan 2022 23:02:30 +0100
Subject: [PATCH 01/12] Add index hint to BoundsError message

---
 base/errorshow.jl            | 34 ++++++++++++++++++++++++++++++++--
 base/strings/string.jl       |  3 +++
 base/tuple.jl                |  4 ++++
 doc/src/manual/interfaces.md |  1 +
 test/arrayops.jl             | 10 +++++-----
 test/errorshow.jl            | 11 ++++++-----
 6 files changed, 51 insertions(+), 12 deletions(-)

diff --git a/base/errorshow.jl b/base/errorshow.jl
index 121fb50db91c1..79c7395df1177 100644
--- a/base/errorshow.jl
+++ b/base/errorshow.jl
@@ -32,9 +32,25 @@ showerror(io::IO, ex) = show(io, ex)
 show_index(io::IO, x::Any) = show(io, x)
 show_index(io::IO, x::Slice) = show_index(io, x.indices)
 show_index(io::IO, x::LogicalIndex) = summary(io, x.mask)
-show_index(io::IO, x::OneTo) = print(io, "1:", x.stop)
+function show_index(io::IO, x::OneTo)
+    if x.stop == 1
+        return print(io, '1')
+    end
+    print(io, "1:", x.stop)
+end
 show_index(io::IO, x::Colon) = print(io, ':')
-
+function show_index(io::IO, x::Tuple)
+    if length(x) == 1
+        return show_index(io, only(x))
+    end
+    print(io, '[')
+    show_index(io, first(x))
+    for el in x[2:end]
+        print(io, ", ")
+        show_index(io, el)
+    end
+    print(io, ']')
+end
 
 function showerror(io::IO, ex::BoundsError)
     print(io, "BoundsError")
@@ -55,10 +71,24 @@ function showerror(io::IO, ex::BoundsError)
             end
             print(io, ']')
         end
+        print(io, ".\nLegal indices are ")
+        show_legal_indices(io, ex.a)
     end
     Experimental.show_error_hints(io, ex)
 end
 
+"""
+    show_legal_indices(io, x)
+
+Describe legal ways to index `x` in human-readable form. This should be a continuation of
+the sentence "Legal indices are ...". Will be shown to the user upon `BoundsError`.
+"""
+show_legal_indices(io::IO, x::Any) = print(io, "unknown.");
+function show_legal_indices(io::IO, x::AbstractArray{<:Any})
+    show_index(io, axes(x))
+    print(io, '.')
+end
+
 function showerror(io::IO, ex::TypeError)
     print(io, "TypeError: ")
     if ex.expected === Bool
diff --git a/base/strings/string.jl b/base/strings/string.jl
index c818e2e1844fb..af61f98bde0b9 100644
--- a/base/strings/string.jl
+++ b/base/strings/string.jl
@@ -24,6 +24,9 @@ function Base.showerror(io::IO, exc::StringIndexError)
         end
     end
 end
+function show_legal_indices(io::IO, s::AbstractString)
+    print(io, "between ", firstindex(s), " and ", thisind(s, ncodeunits(s)), '.')
+end
 
 const ByteArray = Union{CodeUnits{UInt8,String}, Vector{UInt8},Vector{Int8}, FastContiguousSubArray{UInt8,1,CodeUnits{UInt8,String}}, FastContiguousSubArray{UInt8,1,Vector{UInt8}}, FastContiguousSubArray{Int8,1,Vector{Int8}}}
 
diff --git a/base/tuple.jl b/base/tuple.jl
index 5db0e40b495d3..3bd41fdbac89a 100644
--- a/base/tuple.jl
+++ b/base/tuple.jl
@@ -544,6 +544,10 @@ function in(x::Symbol, itr::Tuple{Vararg{Symbol}})
     return sym_in(x, itr)
 end
 
+function show_legal_indices(io::IO, x::Tuple)
+    show_index(io, axes(x))
+    print(io, '.')
+end
 
 """
     empty(x::Tuple)
diff --git a/doc/src/manual/interfaces.md b/doc/src/manual/interfaces.md
index b2ac237dab1a4..38b073a6f8a29 100644
--- a/doc/src/manual/interfaces.md
+++ b/doc/src/manual/interfaces.md
@@ -242,6 +242,7 @@ ourselves, we can officially define it as a subtype of an [`AbstractArray`](@ref
 | `axes(A)`                                    | `map(OneTo, size(A))`                  | Return a tuple of `AbstractUnitRange{<:Integer}` of valid indices                    |
 | `similar(A, ::Type{S}, inds)`              | `similar(A, S, Base.to_shape(inds))`   | Return a mutable array with the specified indices `inds` (see below)                  |
 | `similar(T::Union{Type,Function}, inds)`   | `T(Base.to_shape(inds))`               | Return an array similar to `T` with the specified indices `inds` (see below)          |
+| `show_legal_indices(io, A)` | `Base.show_index(io, axes(A)); print(io, '.');` | Human readable continuation of the sentence "Legal indices are ...", for the `BoundsError` message |
 
 If a type is defined as a subtype of `AbstractArray`, it inherits a very large set of rich behaviors
 including iteration and multidimensional indexing built on top of single-element access.  See
diff --git a/test/arrayops.jl b/test/arrayops.jl
index abdf61e654c01..049f9889e2148 100644
--- a/test/arrayops.jl
+++ b/test/arrayops.jl
@@ -2900,29 +2900,29 @@ end
     b = IOBuffer()
     showerror(b, err)
     @test String(take!(b)) ==
-        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, 1:2]"
+        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, 1:2].\nLegal indices are [1:2, 1:2]."
 
     err = try x[10, trues(2)]; catch err; err; end
     b = IOBuffer()
     showerror(b, err)
     @test String(take!(b)) ==
-        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, 2-element BitVector]"
+        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, 2-element BitVector].\nLegal indices are [1:2, 1:2]."
 
     # Also test : directly for custom types for which it may appear as-is
     err = BoundsError(x, (10, :))
     showerror(b, err)
     @test String(take!(b)) ==
-        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, :]"
+        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, :].\nLegal indices are [1:3, 1:3]."
 
     err = BoundsError(x, "bad index")
     showerror(b, err)
     @test String(take!(b)) ==
-        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [\"bad index\"]"
+        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [\"bad index\"].\nLegal indices are [1:2, 1:2]."
 
     err = BoundsError(x, (10, "bad index"))
     showerror(b, err)
     @test String(take!(b)) ==
-        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, \"bad index\"]"
+        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, \"bad index\"].\nLegal indices are [1:2, 1:2]."
 end
 
 @testset "inference of Union{T,Nothing} arrays 26771" begin
diff --git a/test/errorshow.jl b/test/errorshow.jl
index 72a2ebb1e9cbe..2249069b4ac0e 100644
--- a/test/errorshow.jl
+++ b/test/errorshow.jl
@@ -283,6 +283,7 @@ struct Bounded  # not an AbstractArray
 end
 Base.getindex(b::Bounded, i) = checkindex(Bool, 1:b.bound, i) || throw(BoundsError(b, i))
 Base.summary(io::IO, b::Bounded) = print(io, "$(b.bound)-size Bounded")
+Base.show_legal_indices(io::IO, b::Bounded) = print(io, "1:$(b.bound).")
 let undefvar
     err_str = @except_strbt sqrt(-1) DomainError
     @test occursin("Try sqrt(Complex(x)).", err_str)
@@ -297,17 +298,17 @@ let undefvar
     @test occursin("DomainError with [0.0 -1.0 …", err_str)
 
     err_str = @except_str (1, 2, 3)[4] BoundsError
-    @test err_str == "BoundsError: attempt to access Tuple{$Int, $Int, $Int} at index [4]"
+    @test err_str == "BoundsError: attempt to access Tuple{$Int, $Int, $Int} at index [4].\nLegal indices are 1:3."
 
     err_str = @except_str [5, 4, 3][-2, 1] BoundsError
-    @test err_str == "BoundsError: attempt to access 3-element Vector{$Int} at index [-2, 1]"
+    @test err_str == "BoundsError: attempt to access 3-element Vector{$Int} at index [-2, 1].\nLegal indices are 1:3."
     err_str = @except_str [5, 4, 3][1:5] BoundsError
-    @test err_str == "BoundsError: attempt to access 3-element Vector{$Int} at index [1:5]"
+    @test err_str == "BoundsError: attempt to access 3-element Vector{$Int} at index [1:5].\nLegal indices are 1:3."
     err_str = @except_str [5, 4, 3][trues(6,7)] BoundsError
-    @test err_str == "BoundsError: attempt to access 3-element Vector{$Int} at index [6×7 BitMatrix]"
+    @test err_str == "BoundsError: attempt to access 3-element Vector{$Int} at index [6×7 BitMatrix].\nLegal indices are 1:3."
 
     err_str = @except_str Bounded(2)[3] BoundsError
-    @test err_str == "BoundsError: attempt to access 2-size Bounded at index [3]"
+    @test err_str == "BoundsError: attempt to access 2-size Bounded at index [3].\nLegal indices are 1:2."
 
     err_str = @except_str 0::Bool TypeError
     @test err_str == "TypeError: non-boolean ($Int) used in boolean context"

From fb986ec9071ea54dd3ceb961757ededdb75163dc Mon Sep 17 00:00:00 2001
From: David Gustavsson <david.e.gustavsson@gmail.com>
Date: Sun, 16 Jan 2022 16:08:11 +0100
Subject: [PATCH 02/12] Update tests and docs

---
 base/array.jl                  |  3 ++-
 base/docs/basedocs.jl          | 12 ++++++++----
 base/essentials.jl             |  3 ++-
 base/strings/basic.jl          | 12 ++++++++----
 base/strings/io.jl             |  2 +-
 doc/src/manual/arrays.md       |  3 ++-
 doc/src/manual/strings.md      |  6 ++++--
 stdlib/Dates/docs/src/index.md |  3 ++-
 stdlib/Test/test/runtests.jl   |  2 +-
 test/arrayops.jl               |  2 +-
 10 files changed, 31 insertions(+), 17 deletions(-)

diff --git a/base/array.jl b/base/array.jl
index 2fc1ccfdf7dda..bfaa176b194cf 100644
--- a/base/array.jl
+++ b/base/array.jl
@@ -1343,7 +1343,8 @@ julia> popat!(a, 4, missing)
 missing
 
 julia> popat!(a, 4)
-ERROR: BoundsError: attempt to access 3-element Vector{Int64} at index [4]
+ERROR: BoundsError: attempt to access 3-element Vector{Int64} at index [4].
+Legal indices are 1:3.
 [...]
 ```
 """
diff --git a/base/docs/basedocs.jl b/base/docs/basedocs.jl
index 3cbe180233d9c..abaf72a036ef5 100644
--- a/base/docs/basedocs.jl
+++ b/base/docs/basedocs.jl
@@ -351,7 +351,8 @@ julia> b[1] = 2; a, b, c
 Assignment at out-of-bounds indices does not grow a collection. If the collection is a [`Vector`](@ref) it can instead be grown with [`push!`](@ref) or [`append!`](@ref).
 ```jldoctest
 julia> a = [1, 1]; a[3] = 2
-ERROR: BoundsError: attempt to access 2-element Array{Int64, 1} at index [3]
+ERROR: BoundsError: attempt to access 2-element Array{Int64, 1} at index [3].
+Legal indices are 1:2.
 [...]
 
 julia> push!(a, 2, 3)
@@ -1482,17 +1483,20 @@ An indexing operation into an array, `a`, tried to access an out-of-bounds eleme
 julia> A = fill(1.0, 7);
 
 julia> A[8]
-ERROR: BoundsError: attempt to access 7-element Vector{Float64} at index [8]
+ERROR: BoundsError: attempt to access 7-element Vector{Float64} at index [8].
+Legal indices are 1:7.
 
 
 julia> B = fill(1.0, (2,3));
 
 julia> B[2, 4]
-ERROR: BoundsError: attempt to access 2×3 Matrix{Float64} at index [2, 4]
+ERROR: BoundsError: attempt to access 2×3 Matrix{Float64} at index [2, 4].
+Legal indices are [1:2, 1:3].
 
 
 julia> B[9]
-ERROR: BoundsError: attempt to access 2×3 Matrix{Float64} at index [9]
+ERROR: BoundsError: attempt to access 2×3 Matrix{Float64} at index [9].
+Legal indices are [1:2, 1:3].
 
 ```
 """
diff --git a/base/essentials.jl b/base/essentials.jl
index dd410b06cc8d9..8a2226d892da5 100644
--- a/base/essentials.jl
+++ b/base/essentials.jl
@@ -523,7 +523,8 @@ julia> f1() = return g(1:2, -1);
 julia> f2() = @inbounds return g(1:2, -1);
 
 julia> f1()
-ERROR: BoundsError: attempt to access 2-element UnitRange{Int64} at index [-1]
+ERROR: BoundsError: attempt to access 2-element UnitRange{Int64} at index [-1].
+Legal indices are 1:2.
 Stacktrace:
  [1] throw_boundserror(::UnitRange{Int64}, ::Tuple{Int64}) at ./abstractarray.jl:455
  [2] checkbounds at ./abstractarray.jl:420 [inlined]
diff --git a/base/strings/basic.jl b/base/strings/basic.jl
index 515b836311698..1d8ccbe6b4228 100644
--- a/base/strings/basic.jl
+++ b/base/strings/basic.jl
@@ -425,11 +425,13 @@ julia> thisind("α", 3)
 3
 
 julia> thisind("α", 4)
-ERROR: BoundsError: attempt to access 2-codeunit String at index [4]
+ERROR: BoundsError: attempt to access 2-codeunit String at index [4].
+Legal indices are between 1 and 1.
 [...]
 
 julia> thisind("α", -1)
-ERROR: BoundsError: attempt to access 2-codeunit String at index [-1]
+ERROR: BoundsError: attempt to access 2-codeunit String at index [-1].
+Legal indices are 1 and 1.
 [...]
 ```
 """
@@ -479,7 +481,8 @@ julia> prevind("α", 1)
 0
 
 julia> prevind("α", 0)
-ERROR: BoundsError: attempt to access 2-codeunit String at index [0]
+ERROR: BoundsError: attempt to access 2-codeunit String at index [0].
+Legal indices are between 1 and 1.
 [...]
 
 julia> prevind("α", 2, 2)
@@ -538,7 +541,8 @@ julia> nextind("α", 1)
 3
 
 julia> nextind("α", 3)
-ERROR: BoundsError: attempt to access 2-codeunit String at index [3]
+ERROR: BoundsError: attempt to access 2-codeunit String at index [3].
+Legal indices are between 1 and 1.
 [...]
 
 julia> nextind("α", 0, 2)
diff --git a/base/strings/io.jl b/base/strings/io.jl
index fffe7904ebf92..31556beb327aa 100644
--- a/base/strings/io.jl
+++ b/base/strings/io.jl
@@ -101,7 +101,7 @@ julia> sprint(show, 66.66666; context=:compact => true)
 "66.6667"
 
 julia> sprint(showerror, BoundsError([1], 100))
-"BoundsError: attempt to access 1-element Vector{Int64} at index [100]"
+"BoundsError: attempt to access 1-element Vector{Int64} at index [100].\nLegal indices are 1."
 ```
 """
 function sprint(f::Function, args...; context=nothing, sizehint::Integer=0)
diff --git a/doc/src/manual/arrays.md b/doc/src/manual/arrays.md
index f6e4350726269..8c5e1232fb022 100644
--- a/doc/src/manual/arrays.md
+++ b/doc/src/manual/arrays.md
@@ -907,7 +907,8 @@ julia> A[1, 3, 2] # Omits the fourth dimension (length 1)
 19
 
 julia> A[1, 3] # Attempts to omit dimensions 3 & 4 (lengths 2 and 1)
-ERROR: BoundsError: attempt to access 3×4×2×1 reshape(::UnitRange{Int64}, 3, 4, 2, 1) with eltype Int64 at index [1, 3]
+ERROR: BoundsError: attempt to access 3×4×2×1 reshape(::UnitRange{Int64}, 3, 4, 2, 1) with eltype Int64 at index [1, 3].
+Legal indices are [1:3, 1:4, 1:2, 1].
 
 julia> A[19] # Linear indexing
 19
diff --git a/doc/src/manual/strings.md b/doc/src/manual/strings.md
index 5628c4fa96d81..cd4c56b7779f9 100644
--- a/doc/src/manual/strings.md
+++ b/doc/src/manual/strings.md
@@ -213,11 +213,13 @@ Using an index less than `begin` (`1`) or greater than `end` raises an error:
 
 ```jldoctest helloworldstring
 julia> str[begin-1]
-ERROR: BoundsError: attempt to access 14-codeunit String at index [0]
+ERROR: BoundsError: attempt to access 14-codeunit String at index [0].
+Legal indices are between 1 and 14.
 [...]
 
 julia> str[end+1]
-ERROR: BoundsError: attempt to access 14-codeunit String at index [15]
+ERROR: BoundsError: attempt to access 14-codeunit String at index [15].
+Legal indices are between 1 and 14.
 [...]
 ```
 
diff --git a/stdlib/Dates/docs/src/index.md b/stdlib/Dates/docs/src/index.md
index 4975f175bbf16..02792e82f6984 100644
--- a/stdlib/Dates/docs/src/index.md
+++ b/stdlib/Dates/docs/src/index.md
@@ -367,7 +367,8 @@ function `dayabbr` will error.
 
 ```jldoctest tdate2
 julia> Dates.dayabbr(t;locale="french")
-ERROR: BoundsError: attempt to access 1-element Vector{String} at index [5]
+ERROR: BoundsError: attempt to access 1-element Vector{String} at index [5].
+Legal indices are 1.
 Stacktrace:
 [...]
 ```
diff --git a/stdlib/Test/test/runtests.jl b/stdlib/Test/test/runtests.jl
index 260202462d81a..a7bf1ddc6925f 100644
--- a/stdlib/Test/test/runtests.jl
+++ b/stdlib/Test/test/runtests.jl
@@ -103,7 +103,7 @@ end
     @test endswith(sprint(show, @test_throws str->occursin("a t", str) error("a test")),
                    "Message: \"a test\"")
     @test endswith(sprint(show, @test_throws ["BoundsError", "access", "1-element", "at index [2]"] [1][2]),
-                   "Message: \"BoundsError: attempt to access 1-element Vector{$Int} at index [2]\"")
+                   "Message: \"BoundsError: attempt to access 1-element Vector{$Int} at index [2]\\nLegal indices are 1.\"")
     @test_throws "\"" throw("\"")
     @test_throws Returns(false) throw(Returns(false))
 end
diff --git a/test/arrayops.jl b/test/arrayops.jl
index 049f9889e2148..067d4c22c8530 100644
--- a/test/arrayops.jl
+++ b/test/arrayops.jl
@@ -2912,7 +2912,7 @@ end
     err = BoundsError(x, (10, :))
     showerror(b, err)
     @test String(take!(b)) ==
-        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, :].\nLegal indices are [1:3, 1:3]."
+        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, :].\nLegal indices are [1:2, 1:2]."
 
     err = BoundsError(x, "bad index")
     showerror(b, err)

From 6a2a0e418332eda781762bd1407c5e9d3b1cb57c Mon Sep 17 00:00:00 2001
From: David Gustavsson <david.e.gustavsson@gmail.com>
Date: Wed, 19 Jan 2022 22:08:10 +0100
Subject: [PATCH 03/12] Fix doctest

---
 base/strings/basic.jl | 2 +-
 base/strings/io.jl    | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/base/strings/basic.jl b/base/strings/basic.jl
index 1d8ccbe6b4228..fe5c422e77732 100644
--- a/base/strings/basic.jl
+++ b/base/strings/basic.jl
@@ -431,7 +431,7 @@ Legal indices are between 1 and 1.
 
 julia> thisind("α", -1)
 ERROR: BoundsError: attempt to access 2-codeunit String at index [-1].
-Legal indices are 1 and 1.
+Legal indices are between 1 and 1.
 [...]
 ```
 """
diff --git a/base/strings/io.jl b/base/strings/io.jl
index 31556beb327aa..17605181979ee 100644
--- a/base/strings/io.jl
+++ b/base/strings/io.jl
@@ -101,7 +101,7 @@ julia> sprint(show, 66.66666; context=:compact => true)
 "66.6667"
 
 julia> sprint(showerror, BoundsError([1], 100))
-"BoundsError: attempt to access 1-element Vector{Int64} at index [100].\nLegal indices are 1."
+"BoundsError: attempt to access 1-element Vector{Int64} at index [100].\\nLegal indices are 1."
 ```
 """
 function sprint(f::Function, args...; context=nothing, sizehint::Integer=0)

From 93bc6b763a23fe12ad1635220487638b644b0974 Mon Sep 17 00:00:00 2001
From: David Gustavsson <david.e.gustavsson@gmail.com>
Date: Thu, 20 Jan 2022 09:00:13 +0100
Subject: [PATCH 04/12] Fix another test typo

---
 stdlib/Test/test/runtests.jl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/stdlib/Test/test/runtests.jl b/stdlib/Test/test/runtests.jl
index a7bf1ddc6925f..78ae3c93ec651 100644
--- a/stdlib/Test/test/runtests.jl
+++ b/stdlib/Test/test/runtests.jl
@@ -103,7 +103,7 @@ end
     @test endswith(sprint(show, @test_throws str->occursin("a t", str) error("a test")),
                    "Message: \"a test\"")
     @test endswith(sprint(show, @test_throws ["BoundsError", "access", "1-element", "at index [2]"] [1][2]),
-                   "Message: \"BoundsError: attempt to access 1-element Vector{$Int} at index [2]\\nLegal indices are 1.\"")
+                   "Message: \"BoundsError: attempt to access 1-element Vector{$Int} at index [2].\\nLegal indices are 1.\"")
     @test_throws "\"" throw("\"")
     @test_throws Returns(false) throw(Returns(false))
 end

From 06f75255818db67f9c4dc7dc8fdf8e7f4f89f795 Mon Sep 17 00:00:00 2001
From: David Gustavsson <david.e.gustavsson@gmail.com>
Date: Sat, 22 Jan 2022 18:23:09 +0100
Subject: [PATCH 05/12] Legal->Valid, use register_error_hint, expand docs

---
 base/abstractarray.jl          |  6 ++++++
 base/array.jl                  |  4 ++--
 base/docs/basedocs.jl          | 16 ++++++++--------
 base/errorshow.jl              | 28 +++++++++++++++++----------
 base/essentials.jl             |  4 ++--
 base/strings/basic.jl          | 16 ++++++++--------
 base/strings/io.jl             |  2 +-
 base/strings/string.jl         | 11 ++++++++---
 base/tuple.jl                  |  5 +++--
 doc/src/manual/arrays.md       |  4 ++--
 doc/src/manual/interfaces.md   | 35 +++++++++++++++++++++++++++++++++-
 doc/src/manual/strings.md      |  8 ++++----
 stdlib/Dates/docs/src/index.md |  4 ++--
 stdlib/Test/test/runtests.jl   |  2 +-
 test/arrayops.jl               | 10 +++++-----
 test/errorshow.jl              | 12 ++++++------
 16 files changed, 110 insertions(+), 57 deletions(-)

diff --git a/base/abstractarray.jl b/base/abstractarray.jl
index 2733b52222e37..6c4f89fdf3dfb 100644
--- a/base/abstractarray.jl
+++ b/base/abstractarray.jl
@@ -696,6 +696,12 @@ checkbounds_indices(::Type{Bool}, ::Tuple{}, ::Tuple{}) = true
 
 throw_boundserror(A, I) = (@noinline; throw(BoundsError(A, I)))
 
+function describe_valid_indices(io::IO, a::AbstractArray{<:Any}, i=nothing)
+    print(io, "Valid indices are ")
+    show_index(io, axes(a))
+    print(io, '.')
+end
+
 # check along a single dimension
 """
     checkindex(Bool, inds::AbstractUnitRange, index)
diff --git a/base/array.jl b/base/array.jl
index bfaa176b194cf..2085c2b2cd988 100644
--- a/base/array.jl
+++ b/base/array.jl
@@ -1343,8 +1343,8 @@ julia> popat!(a, 4, missing)
 missing
 
 julia> popat!(a, 4)
-ERROR: BoundsError: attempt to access 3-element Vector{Int64} at index [4].
-Legal indices are 1:3.
+ERROR: BoundsError: attempt to access 3-element Vector{Int64} at index [4]
+Valid indices are 1:3.
 [...]
 ```
 """
diff --git a/base/docs/basedocs.jl b/base/docs/basedocs.jl
index abaf72a036ef5..19de6d213b34a 100644
--- a/base/docs/basedocs.jl
+++ b/base/docs/basedocs.jl
@@ -351,8 +351,8 @@ julia> b[1] = 2; a, b, c
 Assignment at out-of-bounds indices does not grow a collection. If the collection is a [`Vector`](@ref) it can instead be grown with [`push!`](@ref) or [`append!`](@ref).
 ```jldoctest
 julia> a = [1, 1]; a[3] = 2
-ERROR: BoundsError: attempt to access 2-element Array{Int64, 1} at index [3].
-Legal indices are 1:2.
+ERROR: BoundsError: attempt to access 2-element Array{Int64, 1} at index [3]
+Valid indices are 1:2.
 [...]
 
 julia> push!(a, 2, 3)
@@ -1483,20 +1483,20 @@ An indexing operation into an array, `a`, tried to access an out-of-bounds eleme
 julia> A = fill(1.0, 7);
 
 julia> A[8]
-ERROR: BoundsError: attempt to access 7-element Vector{Float64} at index [8].
-Legal indices are 1:7.
+ERROR: BoundsError: attempt to access 7-element Vector{Float64} at index [8]
+Valid indices are 1:7.
 
 
 julia> B = fill(1.0, (2,3));
 
 julia> B[2, 4]
-ERROR: BoundsError: attempt to access 2×3 Matrix{Float64} at index [2, 4].
-Legal indices are [1:2, 1:3].
+ERROR: BoundsError: attempt to access 2×3 Matrix{Float64} at index [2, 4]
+Valid indices are [1:2, 1:3].
 
 
 julia> B[9]
-ERROR: BoundsError: attempt to access 2×3 Matrix{Float64} at index [9].
-Legal indices are [1:2, 1:3].
+ERROR: BoundsError: attempt to access 2×3 Matrix{Float64} at index [9]
+Valid indices are [1:2, 1:3].
 
 ```
 """
diff --git a/base/errorshow.jl b/base/errorshow.jl
index 79c7395df1177..7a257722747b4 100644
--- a/base/errorshow.jl
+++ b/base/errorshow.jl
@@ -71,23 +71,31 @@ function showerror(io::IO, ex::BoundsError)
             end
             print(io, ']')
         end
-        print(io, ".\nLegal indices are ")
-        show_legal_indices(io, ex.a)
     end
     Experimental.show_error_hints(io, ex)
 end
 
+Experimental.register_error_hint(BoundsError) do io, ex
+    print(io,'\n')
+    if ~isdefined(ex, :a)
+        return print(io, "No description of valid indices available.")
+    end
+    if isdefined(ex, :i)
+        return describe_valid_indices(io, ex.a, ex.i)
+    end
+    describe_valid_indices(io, ex.a)
+end
+
 """
-    show_legal_indices(io, x)
+    describe_valid_indices(io, a, i)
 
-Describe legal ways to index `x` in human-readable form. This should be a continuation of
-the sentence "Legal indices are ...". Will be shown to the user upon `BoundsError`.
+Describe valid ways to index `a` in human-readable form. This should typically be a full
+sentence starting "Valid indices are ". Will be shown to the user upon `BoundsError`.
+
+`i` may be ignored, but could be used to determine what information to show.
 """
-show_legal_indices(io::IO, x::Any) = print(io, "unknown.");
-function show_legal_indices(io::IO, x::AbstractArray{<:Any})
-    show_index(io, axes(x))
-    print(io, '.')
-end
+describe_valid_indices(io::IO, a, i) = print(io, "No description of valid indices available.")
+
 
 function showerror(io::IO, ex::TypeError)
     print(io, "TypeError: ")
diff --git a/base/essentials.jl b/base/essentials.jl
index 8a2226d892da5..406d17c8e7837 100644
--- a/base/essentials.jl
+++ b/base/essentials.jl
@@ -523,8 +523,8 @@ julia> f1() = return g(1:2, -1);
 julia> f2() = @inbounds return g(1:2, -1);
 
 julia> f1()
-ERROR: BoundsError: attempt to access 2-element UnitRange{Int64} at index [-1].
-Legal indices are 1:2.
+ERROR: BoundsError: attempt to access 2-element UnitRange{Int64} at index [-1]
+Valid indices are 1:2.
 Stacktrace:
  [1] throw_boundserror(::UnitRange{Int64}, ::Tuple{Int64}) at ./abstractarray.jl:455
  [2] checkbounds at ./abstractarray.jl:420 [inlined]
diff --git a/base/strings/basic.jl b/base/strings/basic.jl
index fe5c422e77732..be919f7651d40 100644
--- a/base/strings/basic.jl
+++ b/base/strings/basic.jl
@@ -425,13 +425,13 @@ julia> thisind("α", 3)
 3
 
 julia> thisind("α", 4)
-ERROR: BoundsError: attempt to access 2-codeunit String at index [4].
-Legal indices are between 1 and 1.
+ERROR: BoundsError: attempt to access 2-codeunit String at index [4]
+Valid indices are between 1 and 1.
 [...]
 
 julia> thisind("α", -1)
-ERROR: BoundsError: attempt to access 2-codeunit String at index [-1].
-Legal indices are between 1 and 1.
+ERROR: BoundsError: attempt to access 2-codeunit String at index [-1]
+Valid indices are between 1 and 1.
 [...]
 ```
 """
@@ -481,8 +481,8 @@ julia> prevind("α", 1)
 0
 
 julia> prevind("α", 0)
-ERROR: BoundsError: attempt to access 2-codeunit String at index [0].
-Legal indices are between 1 and 1.
+ERROR: BoundsError: attempt to access 2-codeunit String at index [0]
+Valid indices are between 1 and 1.
 [...]
 
 julia> prevind("α", 2, 2)
@@ -541,8 +541,8 @@ julia> nextind("α", 1)
 3
 
 julia> nextind("α", 3)
-ERROR: BoundsError: attempt to access 2-codeunit String at index [3].
-Legal indices are between 1 and 1.
+ERROR: BoundsError: attempt to access 2-codeunit String at index [3]
+Valid indices are between 1 and 1.
 [...]
 
 julia> nextind("α", 0, 2)
diff --git a/base/strings/io.jl b/base/strings/io.jl
index 17605181979ee..d696935c4f4c7 100644
--- a/base/strings/io.jl
+++ b/base/strings/io.jl
@@ -101,7 +101,7 @@ julia> sprint(show, 66.66666; context=:compact => true)
 "66.6667"
 
 julia> sprint(showerror, BoundsError([1], 100))
-"BoundsError: attempt to access 1-element Vector{Int64} at index [100].\\nLegal indices are 1."
+"BoundsError: attempt to access 1-element Vector{Int64} at index [100]\\nValid indices are 1."
 ```
 """
 function sprint(f::Function, args...; context=nothing, sizehint::Integer=0)
diff --git a/base/strings/string.jl b/base/strings/string.jl
index af61f98bde0b9..a8b705458f2f4 100644
--- a/base/strings/string.jl
+++ b/base/strings/string.jl
@@ -24,9 +24,14 @@ function Base.showerror(io::IO, exc::StringIndexError)
         end
     end
 end
-function show_legal_indices(io::IO, s::AbstractString)
-    print(io, "between ", firstindex(s), " and ", thisind(s, ncodeunits(s)), '.')
-end
+
+describe_valid_indices(io::IO, a::AbstractString, i=nothing) = print(io,
+                                                                     "Valid indices are between ",
+                                                                     firstindex(a),
+                                                                     " and ",
+                                                                     thisind(a, ncodeunits(a)),
+                                                                     '.'
+                                                                    )
 
 const ByteArray = Union{CodeUnits{UInt8,String}, Vector{UInt8},Vector{Int8}, FastContiguousSubArray{UInt8,1,CodeUnits{UInt8,String}}, FastContiguousSubArray{UInt8,1,Vector{UInt8}}, FastContiguousSubArray{Int8,1,Vector{Int8}}}
 
diff --git a/base/tuple.jl b/base/tuple.jl
index 3bd41fdbac89a..3ec4a10ecaa14 100644
--- a/base/tuple.jl
+++ b/base/tuple.jl
@@ -544,8 +544,9 @@ function in(x::Symbol, itr::Tuple{Vararg{Symbol}})
     return sym_in(x, itr)
 end
 
-function show_legal_indices(io::IO, x::Tuple)
-    show_index(io, axes(x))
+function describe_valid_indices(io::IO, a::Tuple, i=nothing)
+    print(io, "Valid indices are ")
+    show_index(io, axes(a))
     print(io, '.')
 end
 
diff --git a/doc/src/manual/arrays.md b/doc/src/manual/arrays.md
index 8c5e1232fb022..5c3b8d0cddbeb 100644
--- a/doc/src/manual/arrays.md
+++ b/doc/src/manual/arrays.md
@@ -907,8 +907,8 @@ julia> A[1, 3, 2] # Omits the fourth dimension (length 1)
 19
 
 julia> A[1, 3] # Attempts to omit dimensions 3 & 4 (lengths 2 and 1)
-ERROR: BoundsError: attempt to access 3×4×2×1 reshape(::UnitRange{Int64}, 3, 4, 2, 1) with eltype Int64 at index [1, 3].
-Legal indices are [1:3, 1:4, 1:2, 1].
+ERROR: BoundsError: attempt to access 3×4×2×1 reshape(::UnitRange{Int64}, 3, 4, 2, 1) with eltype Int64 at index [1, 3]
+Valid indices are [1:3, 1:4, 1:2, 1].
 
 julia> A[19] # Linear indexing
 19
diff --git a/doc/src/manual/interfaces.md b/doc/src/manual/interfaces.md
index 38b073a6f8a29..0f002d574da79 100644
--- a/doc/src/manual/interfaces.md
+++ b/doc/src/manual/interfaces.md
@@ -242,7 +242,7 @@ ourselves, we can officially define it as a subtype of an [`AbstractArray`](@ref
 | `axes(A)`                                    | `map(OneTo, size(A))`                  | Return a tuple of `AbstractUnitRange{<:Integer}` of valid indices                    |
 | `similar(A, ::Type{S}, inds)`              | `similar(A, S, Base.to_shape(inds))`   | Return a mutable array with the specified indices `inds` (see below)                  |
 | `similar(T::Union{Type,Function}, inds)`   | `T(Base.to_shape(inds))`               | Return an array similar to `T` with the specified indices `inds` (see below)          |
-| `show_legal_indices(io, A)` | `Base.show_index(io, axes(A)); print(io, '.');` | Human readable continuation of the sentence "Legal indices are ...", for the `BoundsError` message |
+| `describe_valid_indices(io, A, i)` |  | Human readable version of the sentence "Valid indices are ...", for the `BoundsError` message |
 
 If a type is defined as a subtype of `AbstractArray`, it inherits a very large set of rich behaviors
 including iteration and multidimensional indexing built on top of single-element access.  See
@@ -407,6 +407,39 @@ so that the `dims` argument (ordinarily a `Dims` size-tuple) can accept `Abstrac
 perhaps range-types `Ind` of your own design. For more information, see
 [Arrays with custom indices](@ref man-custom-indices).
 
+When a user indexes into an array using an invalid index, a 'BoundsError' is
+thrown. Along with this error, a hint is printed telling the user which indices
+they *could* have used. If there is a more intuitive description of your type's
+valid indices than the default, which uses `axes(A)`, you can define a method
+to `describe_valid_indices(io::IO, A, i)`. If, for instance, we wanted to
+protect our `SparseArray` from bounds errors, we could redefine `getindex`:
+
+```jldoctest squarevectype
+julia> function Base.getindex(A::SparseArray{T,N}, I::Vararg{Int,N}) where {T,N}
+           any(I .> A.dims) && throw(BoundsError(A, I))
+           get(A.data, I, zero(T))
+       end
+
+julia> A[4, 3]
+ERROR: BoundsError: attempt to access 3×3 SparseArray{Float64, 2} at index [0]
+Valid indices are [1:3, 1:3].
+```
+
+So far, this message is not entirely true. We implemented a check for indices
+above the maxima, but `A[0, 0]` will happily evaluate. If this is by intention,
+we can update the error message:
+
+```jldoctest squarevectype
+julia> Base.describe_valid_indices(io::IO, A::SparseArray, i=nothing) = print(io, "Valid indices are <= ", A.dims, '.')
+
+julia> A[0, 0]
+0.0
+
+julia> A[4, 3]
+ERROR: BoundsError: attempt to access 3×3 SparseArray{Float64, 2} at index [4, 3]
+Valid indices are <= (3, 3).
+```
+
 ## [Strided Arrays](@id man-interface-strided-arrays)
 
 | Methods to implement                            |                                        | Brief description                                                                     |
diff --git a/doc/src/manual/strings.md b/doc/src/manual/strings.md
index cd4c56b7779f9..20d930cb53a3f 100644
--- a/doc/src/manual/strings.md
+++ b/doc/src/manual/strings.md
@@ -213,13 +213,13 @@ Using an index less than `begin` (`1`) or greater than `end` raises an error:
 
 ```jldoctest helloworldstring
 julia> str[begin-1]
-ERROR: BoundsError: attempt to access 14-codeunit String at index [0].
-Legal indices are between 1 and 14.
+ERROR: BoundsError: attempt to access 14-codeunit String at index [0]
+Valid indices are between 1 and 14.
 [...]
 
 julia> str[end+1]
-ERROR: BoundsError: attempt to access 14-codeunit String at index [15].
-Legal indices are between 1 and 14.
+ERROR: BoundsError: attempt to access 14-codeunit String at index [15]
+Valid indices are between 1 and 14.
 [...]
 ```
 
diff --git a/stdlib/Dates/docs/src/index.md b/stdlib/Dates/docs/src/index.md
index 02792e82f6984..ad711ce83b963 100644
--- a/stdlib/Dates/docs/src/index.md
+++ b/stdlib/Dates/docs/src/index.md
@@ -367,8 +367,8 @@ function `dayabbr` will error.
 
 ```jldoctest tdate2
 julia> Dates.dayabbr(t;locale="french")
-ERROR: BoundsError: attempt to access 1-element Vector{String} at index [5].
-Legal indices are 1.
+ERROR: BoundsError: attempt to access 1-element Vector{String} at index [5]
+Valid indices are 1.
 Stacktrace:
 [...]
 ```
diff --git a/stdlib/Test/test/runtests.jl b/stdlib/Test/test/runtests.jl
index 78ae3c93ec651..a601eb25265cc 100644
--- a/stdlib/Test/test/runtests.jl
+++ b/stdlib/Test/test/runtests.jl
@@ -103,7 +103,7 @@ end
     @test endswith(sprint(show, @test_throws str->occursin("a t", str) error("a test")),
                    "Message: \"a test\"")
     @test endswith(sprint(show, @test_throws ["BoundsError", "access", "1-element", "at index [2]"] [1][2]),
-                   "Message: \"BoundsError: attempt to access 1-element Vector{$Int} at index [2].\\nLegal indices are 1.\"")
+                   "Message: \"BoundsError: attempt to access 1-element Vector{$Int} at index [2]\\nValid indices are 1.\"")
     @test_throws "\"" throw("\"")
     @test_throws Returns(false) throw(Returns(false))
 end
diff --git a/test/arrayops.jl b/test/arrayops.jl
index 067d4c22c8530..5ad00ca057433 100644
--- a/test/arrayops.jl
+++ b/test/arrayops.jl
@@ -2900,29 +2900,29 @@ end
     b = IOBuffer()
     showerror(b, err)
     @test String(take!(b)) ==
-        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, 1:2].\nLegal indices are [1:2, 1:2]."
+        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, 1:2]\nValid indices are [1:2, 1:2]."
 
     err = try x[10, trues(2)]; catch err; err; end
     b = IOBuffer()
     showerror(b, err)
     @test String(take!(b)) ==
-        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, 2-element BitVector].\nLegal indices are [1:2, 1:2]."
+        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, 2-element BitVector]\nValid indices are [1:2, 1:2]."
 
     # Also test : directly for custom types for which it may appear as-is
     err = BoundsError(x, (10, :))
     showerror(b, err)
     @test String(take!(b)) ==
-        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, :].\nLegal indices are [1:2, 1:2]."
+        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, :]\nValid indices are [1:2, 1:2]."
 
     err = BoundsError(x, "bad index")
     showerror(b, err)
     @test String(take!(b)) ==
-        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [\"bad index\"].\nLegal indices are [1:2, 1:2]."
+        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [\"bad index\"]\nValid indices are [1:2, 1:2]."
 
     err = BoundsError(x, (10, "bad index"))
     showerror(b, err)
     @test String(take!(b)) ==
-        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, \"bad index\"].\nLegal indices are [1:2, 1:2]."
+        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, \"bad index\"]\nValid indices are [1:2, 1:2]."
 end
 
 @testset "inference of Union{T,Nothing} arrays 26771" begin
diff --git a/test/errorshow.jl b/test/errorshow.jl
index 2249069b4ac0e..ca1f3aae03564 100644
--- a/test/errorshow.jl
+++ b/test/errorshow.jl
@@ -283,7 +283,7 @@ struct Bounded  # not an AbstractArray
 end
 Base.getindex(b::Bounded, i) = checkindex(Bool, 1:b.bound, i) || throw(BoundsError(b, i))
 Base.summary(io::IO, b::Bounded) = print(io, "$(b.bound)-size Bounded")
-Base.show_legal_indices(io::IO, b::Bounded) = print(io, "1:$(b.bound).")
+Base.describe_valid_indices(io::IO, b::Bounded, i=nothing) = print(io, "Valid indices are 1:$(b.bound).")
 let undefvar
     err_str = @except_strbt sqrt(-1) DomainError
     @test occursin("Try sqrt(Complex(x)).", err_str)
@@ -298,17 +298,17 @@ let undefvar
     @test occursin("DomainError with [0.0 -1.0 …", err_str)
 
     err_str = @except_str (1, 2, 3)[4] BoundsError
-    @test err_str == "BoundsError: attempt to access Tuple{$Int, $Int, $Int} at index [4].\nLegal indices are 1:3."
+    @test err_str == "BoundsError: attempt to access Tuple{$Int, $Int, $Int} at index [4]\nValid indices are 1:3."
 
     err_str = @except_str [5, 4, 3][-2, 1] BoundsError
-    @test err_str == "BoundsError: attempt to access 3-element Vector{$Int} at index [-2, 1].\nLegal indices are 1:3."
+    @test err_str == "BoundsError: attempt to access 3-element Vector{$Int} at index [-2, 1]\nValid indices are 1:3."
     err_str = @except_str [5, 4, 3][1:5] BoundsError
-    @test err_str == "BoundsError: attempt to access 3-element Vector{$Int} at index [1:5].\nLegal indices are 1:3."
+    @test err_str == "BoundsError: attempt to access 3-element Vector{$Int} at index [1:5]\nValid indices are 1:3."
     err_str = @except_str [5, 4, 3][trues(6,7)] BoundsError
-    @test err_str == "BoundsError: attempt to access 3-element Vector{$Int} at index [6×7 BitMatrix].\nLegal indices are 1:3."
+    @test err_str == "BoundsError: attempt to access 3-element Vector{$Int} at index [6×7 BitMatrix]\nValid indices are 1:3."
 
     err_str = @except_str Bounded(2)[3] BoundsError
-    @test err_str == "BoundsError: attempt to access 2-size Bounded at index [3].\nLegal indices are 1:2."
+    @test err_str == "BoundsError: attempt to access 2-size Bounded at index [3]\nValid indices are 1:2."
 
     err_str = @except_str 0::Bool TypeError
     @test err_str == "TypeError: non-boolean ($Int) used in boolean context"

From 30e07e2dd98d66345f8d10199a80e4ccfa48f071 Mon Sep 17 00:00:00 2001
From: David Gustavsson <david.e.gustavsson@gmail.com>
Date: Sat, 22 Jan 2022 20:10:42 +0100
Subject: [PATCH 06/12] Doc typo

---
 doc/src/manual/interfaces.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/src/manual/interfaces.md b/doc/src/manual/interfaces.md
index 0f002d574da79..d35e474905210 100644
--- a/doc/src/manual/interfaces.md
+++ b/doc/src/manual/interfaces.md
@@ -421,7 +421,7 @@ julia> function Base.getindex(A::SparseArray{T,N}, I::Vararg{Int,N}) where {T,N}
        end
 
 julia> A[4, 3]
-ERROR: BoundsError: attempt to access 3×3 SparseArray{Float64, 2} at index [0]
+ERROR: BoundsError: attempt to access 3×3 SparseArray{Float64, 2} at index [4, 3]
 Valid indices are [1:3, 1:3].
 ```
 

From d2c850c40bbaf31876caa0a3148f130d6bc2e74b Mon Sep 17 00:00:00 2001
From: David Gustavsson <david.e.gustavsson@gmail.com>
Date: Thu, 12 May 2022 14:17:04 +0200
Subject: [PATCH 07/12] Remove error hint for one-to arrays

---
 base/abstractarray.jl        |  3 +++
 base/array.jl                |  1 -
 base/docs/basedocs.jl        |  4 ----
 base/essentials.jl           |  1 -
 doc/src/manual/interfaces.md |  1 -
 test/arrayops.jl             | 10 +++++-----
 test/errorshow.jl            |  8 ++++----
 7 files changed, 12 insertions(+), 16 deletions(-)

diff --git a/base/abstractarray.jl b/base/abstractarray.jl
index 6c4f89fdf3dfb..3991ddcdb1762 100644
--- a/base/abstractarray.jl
+++ b/base/abstractarray.jl
@@ -697,6 +697,9 @@ checkbounds_indices(::Type{Bool}, ::Tuple{}, ::Tuple{}) = true
 throw_boundserror(A, I) = (@noinline; throw(BoundsError(A, I)))
 
 function describe_valid_indices(io::IO, a::AbstractArray{<:Any}, i=nothing)
+    if all(x->isa(axes(x), OneTo), a)
+        return nothing
+    end
     print(io, "Valid indices are ")
     show_index(io, axes(a))
     print(io, '.')
diff --git a/base/array.jl b/base/array.jl
index 2085c2b2cd988..2fc1ccfdf7dda 100644
--- a/base/array.jl
+++ b/base/array.jl
@@ -1344,7 +1344,6 @@ missing
 
 julia> popat!(a, 4)
 ERROR: BoundsError: attempt to access 3-element Vector{Int64} at index [4]
-Valid indices are 1:3.
 [...]
 ```
 """
diff --git a/base/docs/basedocs.jl b/base/docs/basedocs.jl
index 19de6d213b34a..3cbe180233d9c 100644
--- a/base/docs/basedocs.jl
+++ b/base/docs/basedocs.jl
@@ -352,7 +352,6 @@ Assignment at out-of-bounds indices does not grow a collection. If the collectio
 ```jldoctest
 julia> a = [1, 1]; a[3] = 2
 ERROR: BoundsError: attempt to access 2-element Array{Int64, 1} at index [3]
-Valid indices are 1:2.
 [...]
 
 julia> push!(a, 2, 3)
@@ -1484,19 +1483,16 @@ julia> A = fill(1.0, 7);
 
 julia> A[8]
 ERROR: BoundsError: attempt to access 7-element Vector{Float64} at index [8]
-Valid indices are 1:7.
 
 
 julia> B = fill(1.0, (2,3));
 
 julia> B[2, 4]
 ERROR: BoundsError: attempt to access 2×3 Matrix{Float64} at index [2, 4]
-Valid indices are [1:2, 1:3].
 
 
 julia> B[9]
 ERROR: BoundsError: attempt to access 2×3 Matrix{Float64} at index [9]
-Valid indices are [1:2, 1:3].
 
 ```
 """
diff --git a/base/essentials.jl b/base/essentials.jl
index 406d17c8e7837..dd410b06cc8d9 100644
--- a/base/essentials.jl
+++ b/base/essentials.jl
@@ -524,7 +524,6 @@ julia> f2() = @inbounds return g(1:2, -1);
 
 julia> f1()
 ERROR: BoundsError: attempt to access 2-element UnitRange{Int64} at index [-1]
-Valid indices are 1:2.
 Stacktrace:
  [1] throw_boundserror(::UnitRange{Int64}, ::Tuple{Int64}) at ./abstractarray.jl:455
  [2] checkbounds at ./abstractarray.jl:420 [inlined]
diff --git a/doc/src/manual/interfaces.md b/doc/src/manual/interfaces.md
index d35e474905210..7eb1e72c03d3d 100644
--- a/doc/src/manual/interfaces.md
+++ b/doc/src/manual/interfaces.md
@@ -422,7 +422,6 @@ julia> function Base.getindex(A::SparseArray{T,N}, I::Vararg{Int,N}) where {T,N}
 
 julia> A[4, 3]
 ERROR: BoundsError: attempt to access 3×3 SparseArray{Float64, 2} at index [4, 3]
-Valid indices are [1:3, 1:3].
 ```
 
 So far, this message is not entirely true. We implemented a check for indices
diff --git a/test/arrayops.jl b/test/arrayops.jl
index 5ad00ca057433..abdf61e654c01 100644
--- a/test/arrayops.jl
+++ b/test/arrayops.jl
@@ -2900,29 +2900,29 @@ end
     b = IOBuffer()
     showerror(b, err)
     @test String(take!(b)) ==
-        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, 1:2]\nValid indices are [1:2, 1:2]."
+        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, 1:2]"
 
     err = try x[10, trues(2)]; catch err; err; end
     b = IOBuffer()
     showerror(b, err)
     @test String(take!(b)) ==
-        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, 2-element BitVector]\nValid indices are [1:2, 1:2]."
+        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, 2-element BitVector]"
 
     # Also test : directly for custom types for which it may appear as-is
     err = BoundsError(x, (10, :))
     showerror(b, err)
     @test String(take!(b)) ==
-        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, :]\nValid indices are [1:2, 1:2]."
+        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, :]"
 
     err = BoundsError(x, "bad index")
     showerror(b, err)
     @test String(take!(b)) ==
-        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [\"bad index\"]\nValid indices are [1:2, 1:2]."
+        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [\"bad index\"]"
 
     err = BoundsError(x, (10, "bad index"))
     showerror(b, err)
     @test String(take!(b)) ==
-        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, \"bad index\"]\nValid indices are [1:2, 1:2]."
+        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, \"bad index\"]"
 end
 
 @testset "inference of Union{T,Nothing} arrays 26771" begin
diff --git a/test/errorshow.jl b/test/errorshow.jl
index ca1f3aae03564..b0fd478cba1d0 100644
--- a/test/errorshow.jl
+++ b/test/errorshow.jl
@@ -301,14 +301,14 @@ let undefvar
     @test err_str == "BoundsError: attempt to access Tuple{$Int, $Int, $Int} at index [4]\nValid indices are 1:3."
 
     err_str = @except_str [5, 4, 3][-2, 1] BoundsError
-    @test err_str == "BoundsError: attempt to access 3-element Vector{$Int} at index [-2, 1]\nValid indices are 1:3."
+    @test err_str == "BoundsError: attempt to access 3-element Vector{$Int} at index [-2, 1]"
     err_str = @except_str [5, 4, 3][1:5] BoundsError
-    @test err_str == "BoundsError: attempt to access 3-element Vector{$Int} at index [1:5]\nValid indices are 1:3."
+    @test err_str == "BoundsError: attempt to access 3-element Vector{$Int} at index [1:5]"
     err_str = @except_str [5, 4, 3][trues(6,7)] BoundsError
-    @test err_str == "BoundsError: attempt to access 3-element Vector{$Int} at index [6×7 BitMatrix]\nValid indices are 1:3."
+    @test err_str == "BoundsError: attempt to access 3-element Vector{$Int} at index [6×7 BitMatrix]"
 
     err_str = @except_str Bounded(2)[3] BoundsError
-    @test err_str == "BoundsError: attempt to access 2-size Bounded at index [3]\nValid indices are 1:2."
+    @test err_str == "BoundsError: attempt to access 2-size Bounded at index [3]"
 
     err_str = @except_str 0::Bool TypeError
     @test err_str == "TypeError: non-boolean ($Int) used in boolean context"

From c1eb7e9d7fb9b3b51d32c1c726c0af8511be4418 Mon Sep 17 00:00:00 2001
From: David Gustavsson <david.e.gustavsson@gmail.com>
Date: Sat, 7 Jan 2023 11:12:58 +0100
Subject: [PATCH 08/12] Revert "Remove error hint for one-to arrays"

This reverts commit d2c850c40bbaf31876caa0a3148f130d6bc2e74b.
---
 base/abstractarray.jl        |  3 ---
 base/array.jl                |  1 +
 base/docs/basedocs.jl        |  4 ++++
 base/essentials.jl           |  1 +
 doc/src/manual/interfaces.md |  1 +
 test/arrayops.jl             | 10 +++++-----
 test/errorshow.jl            |  6 +++---
 7 files changed, 15 insertions(+), 11 deletions(-)

diff --git a/base/abstractarray.jl b/base/abstractarray.jl
index 1bd49d983aeb8..8c28a3f02b32b 100644
--- a/base/abstractarray.jl
+++ b/base/abstractarray.jl
@@ -744,9 +744,6 @@ checkbounds_indices(::Type{Bool}, ::Tuple{}, ::Tuple{}) = true
 throw_boundserror(A, I) = (@noinline; throw(BoundsError(A, I)))
 
 function describe_valid_indices(io::IO, a::AbstractArray{<:Any}, i=nothing)
-    if all(x->isa(axes(x), OneTo), a)
-        return nothing
-    end
     print(io, "Valid indices are ")
     show_index(io, axes(a))
     print(io, '.')
diff --git a/base/array.jl b/base/array.jl
index 694a3913cacf4..f43e5cf35958e 100644
--- a/base/array.jl
+++ b/base/array.jl
@@ -1365,6 +1365,7 @@ missing
 
 julia> popat!(a, 4)
 ERROR: BoundsError: attempt to access 3-element Vector{Int64} at index [4]
+Valid indices are 1:3.
 [...]
 ```
 """
diff --git a/base/docs/basedocs.jl b/base/docs/basedocs.jl
index 3e86095f181a9..8833fa0423e3f 100644
--- a/base/docs/basedocs.jl
+++ b/base/docs/basedocs.jl
@@ -401,6 +401,7 @@ Assignment at out-of-bounds indices does not grow a collection. If the collectio
 ```jldoctest
 julia> a = [1, 1]; a[3] = 2
 ERROR: BoundsError: attempt to access 2-element Array{Int64, 1} at index [3]
+Valid indices are 1:2.
 [...]
 
 julia> push!(a, 2, 3)
@@ -1675,16 +1676,19 @@ julia> A = fill(1.0, 7);
 
 julia> A[8]
 ERROR: BoundsError: attempt to access 7-element Vector{Float64} at index [8]
+Valid indices are 1:7.
 
 
 julia> B = fill(1.0, (2,3));
 
 julia> B[2, 4]
 ERROR: BoundsError: attempt to access 2×3 Matrix{Float64} at index [2, 4]
+Valid indices are [1:2, 1:3].
 
 
 julia> B[9]
 ERROR: BoundsError: attempt to access 2×3 Matrix{Float64} at index [9]
+Valid indices are [1:2, 1:3].
 
 ```
 """
diff --git a/base/essentials.jl b/base/essentials.jl
index 2093c792dd9b4..0b9da7088da95 100644
--- a/base/essentials.jl
+++ b/base/essentials.jl
@@ -608,6 +608,7 @@ julia> f2() = @inbounds return g(1:2, -1);
 
 julia> f1()
 ERROR: BoundsError: attempt to access 2-element UnitRange{Int64} at index [-1]
+Valid indices are 1:2.
 Stacktrace:
  [1] throw_boundserror(::UnitRange{Int64}, ::Tuple{Int64}) at ./abstractarray.jl:455
  [2] checkbounds at ./abstractarray.jl:420 [inlined]
diff --git a/doc/src/manual/interfaces.md b/doc/src/manual/interfaces.md
index 88b40e0a06275..5a297eb1f0495 100644
--- a/doc/src/manual/interfaces.md
+++ b/doc/src/manual/interfaces.md
@@ -416,6 +416,7 @@ julia> function Base.getindex(A::SparseArray{T,N}, I::Vararg{Int,N}) where {T,N}
 
 julia> A[4, 3]
 ERROR: BoundsError: attempt to access 3×3 SparseArray{Float64, 2} at index [4, 3]
+Valid indices are [1:3, 1:3].
 ```
 
 So far, this message is not entirely true. We implemented a check for indices
diff --git a/test/arrayops.jl b/test/arrayops.jl
index e7ac6a1132568..fbb4b183edb52 100644
--- a/test/arrayops.jl
+++ b/test/arrayops.jl
@@ -3020,29 +3020,29 @@ end
     b = IOBuffer()
     showerror(b, err)
     @test String(take!(b)) ==
-        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, 1:2]"
+        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, 1:2]\nValid indices are [1:2, 1:2]."
 
     err = try x[10, trues(2)]; catch err; err; end
     b = IOBuffer()
     showerror(b, err)
     @test String(take!(b)) ==
-        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, 2-element BitVector]"
+        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, 2-element BitVector]\nValid indices are [1:2, 1:2]."
 
     # Also test : directly for custom types for which it may appear as-is
     err = BoundsError(x, (10, :))
     showerror(b, err)
     @test String(take!(b)) ==
-        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, :]"
+        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, :]\nValid indices are [1:2, 1:2]."
 
     err = BoundsError(x, "bad index")
     showerror(b, err)
     @test String(take!(b)) ==
-        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [\"bad index\"]"
+        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [\"bad index\"]\nValid indices are [1:2, 1:2]."
 
     err = BoundsError(x, (10, "bad index"))
     showerror(b, err)
     @test String(take!(b)) ==
-        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, \"bad index\"]"
+        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, \"bad index\"]\nValid indices are [1:2, 1:2]."
 end
 
 @testset "inference of Union{T,Nothing} arrays 26771" begin
diff --git a/test/errorshow.jl b/test/errorshow.jl
index 64ef4afc887d3..35db0c7bf9a81 100644
--- a/test/errorshow.jl
+++ b/test/errorshow.jl
@@ -307,11 +307,11 @@ let undefvar
     @test err_str == "BoundsError: attempt to access Tuple{$Int, $Int, $Int} at index [4]\nValid indices are 1:3."
 
     err_str = @except_str [5, 4, 3][-2, 1] BoundsError
-    @test err_str == "BoundsError: attempt to access 3-element Vector{$Int} at index [-2, 1]"
+    @test err_str == "BoundsError: attempt to access 3-element Vector{$Int} at index [-2, 1]\nValid indices are 1:3."
     err_str = @except_str [5, 4, 3][1:5] BoundsError
-    @test err_str == "BoundsError: attempt to access 3-element Vector{$Int} at index [1:5]"
+    @test err_str == "BoundsError: attempt to access 3-element Vector{$Int} at index [1:5]\nValid indices are 1:3."
     err_str = @except_str [5, 4, 3][trues(6,7)] BoundsError
-    @test err_str == "BoundsError: attempt to access 3-element Vector{$Int} at index [6×7 BitMatrix]"
+    @test err_str == "BoundsError: attempt to access 3-element Vector{$Int} at index [6×7 BitMatrix]\nValid indices are 1:3."
 
     err_str = @except_str Bounded(2)[3] BoundsError
     @test err_str == "BoundsError: attempt to access 2-size Bounded at index [3]"

From cb939a31906f79dc436d4bd54c08cad494924ed6 Mon Sep 17 00:00:00 2001
From: David Gustavsson <david.e.gustavsson@gmail.com>
Date: Sat, 7 Jan 2023 11:08:32 +0100
Subject: [PATCH 09/12] More newlines

---
 base/abstractarray.jl  | 2 +-
 base/errorshow.jl      | 7 +++----
 base/strings/string.jl | 2 +-
 base/tuple.jl          | 2 +-
 test/errorshow.jl      | 4 ++--
 5 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/base/abstractarray.jl b/base/abstractarray.jl
index 8c28a3f02b32b..73ccbf533c8e9 100644
--- a/base/abstractarray.jl
+++ b/base/abstractarray.jl
@@ -744,7 +744,7 @@ checkbounds_indices(::Type{Bool}, ::Tuple{}, ::Tuple{}) = true
 throw_boundserror(A, I) = (@noinline; throw(BoundsError(A, I)))
 
 function describe_valid_indices(io::IO, a::AbstractArray{<:Any}, i=nothing)
-    print(io, "Valid indices are ")
+    print(io, "\nValid indices are ")
     show_index(io, axes(a))
     print(io, '.')
 end
diff --git a/base/errorshow.jl b/base/errorshow.jl
index a23f9f609c1a8..18d87ea9c3365 100644
--- a/base/errorshow.jl
+++ b/base/errorshow.jl
@@ -76,9 +76,8 @@ function showerror(io::IO, ex::BoundsError)
 end
 
 Experimental.register_error_hint(BoundsError) do io, ex
-    print(io,'\n')
     if ~isdefined(ex, :a)
-        return print(io, "No description of valid indices available.")
+        return print(io, "\nNo description of valid indices available.")
     end
     if isdefined(ex, :i)
         return describe_valid_indices(io, ex.a, ex.i)
@@ -90,11 +89,11 @@ end
     describe_valid_indices(io, a, i)
 
 Describe valid ways to index `a` in human-readable form. This should typically be a full
-sentence starting "Valid indices are ". Will be shown to the user upon `BoundsError`.
+sentence starting "\nValid indices are ". Will be shown to the user upon `BoundsError`.
 
 `i` may be ignored, but could be used to determine what information to show.
 """
-describe_valid_indices(io::IO, a, i) = print(io, "No description of valid indices available.")
+describe_valid_indices(io::IO, a, i) = print(io, "\nNo description of valid indices available.")
 
 
 function showerror(io::IO, ex::TypeError)
diff --git a/base/strings/string.jl b/base/strings/string.jl
index 6c44aae3ae56a..4becc9ccc4741 100644
--- a/base/strings/string.jl
+++ b/base/strings/string.jl
@@ -28,7 +28,7 @@ function Base.showerror(io::IO, exc::StringIndexError)
 end
 
 describe_valid_indices(io::IO, a::AbstractString, i=nothing) = print(io,
-                                                                     "Valid indices are between ",
+                                                                     "\nValid indices are between ",
                                                                      firstindex(a),
                                                                      " and ",
                                                                      thisind(a, ncodeunits(a)),
diff --git a/base/tuple.jl b/base/tuple.jl
index e6434c1d06501..0a06e66c083ce 100644
--- a/base/tuple.jl
+++ b/base/tuple.jl
@@ -592,7 +592,7 @@ end
 in(x::Symbol, @nospecialize itr::Tuple{Vararg{Symbol}}) = sym_in(x, itr)
 
 function describe_valid_indices(io::IO, a::Tuple, i=nothing)
-    print(io, "Valid indices are ")
+    print(io, "\nValid indices are ")
     show_index(io, axes(a))
     print(io, '.')
 end
diff --git a/test/errorshow.jl b/test/errorshow.jl
index 35db0c7bf9a81..f8845e1459047 100644
--- a/test/errorshow.jl
+++ b/test/errorshow.jl
@@ -289,7 +289,7 @@ struct Bounded  # not an AbstractArray
 end
 Base.getindex(b::Bounded, i) = checkindex(Bool, 1:b.bound, i) || throw(BoundsError(b, i))
 Base.summary(io::IO, b::Bounded) = print(io, "$(b.bound)-size Bounded")
-Base.describe_valid_indices(io::IO, b::Bounded, i=nothing) = print(io, "Valid indices are 1:$(b.bound).")
+Base.describe_valid_indices(io::IO, b::Bounded, i=nothing) = print(io, "\nValid indices are 1:$(b.bound).")
 let undefvar
     err_str = @except_strbt sqrt(-1) DomainError
     @test occursin("Try sqrt(Complex(x)).", err_str)
@@ -314,7 +314,7 @@ let undefvar
     @test err_str == "BoundsError: attempt to access 3-element Vector{$Int} at index [6×7 BitMatrix]\nValid indices are 1:3."
 
     err_str = @except_str Bounded(2)[3] BoundsError
-    @test err_str == "BoundsError: attempt to access 2-size Bounded at index [3]"
+    @test err_str == "BoundsError: attempt to access 2-size Bounded at index [3]\nValid indices are 1:2."
 
     err_str = @except_str 0::Bool TypeError
     @test err_str == "TypeError: non-boolean ($Int) used in boolean context"

From 3a161bf2a2395b96666fc0701f3ed8cf002ca3c3 Mon Sep 17 00:00:00 2001
From: David Gustavsson <david.e.gustavsson@gmail.com>
Date: Sat, 7 Jan 2023 16:38:55 +0100
Subject: [PATCH 10/12] Remove "between 1 and 1"

---
 base/strings/basic.jl  |  8 ++++----
 base/strings/string.jl | 22 +++++++++++++++-------
 2 files changed, 19 insertions(+), 11 deletions(-)

diff --git a/base/strings/basic.jl b/base/strings/basic.jl
index b6a8e4427c464..d0ac8848c72e6 100644
--- a/base/strings/basic.jl
+++ b/base/strings/basic.jl
@@ -429,12 +429,12 @@ julia> thisind("α", 3)
 
 julia> thisind("α", 4)
 ERROR: BoundsError: attempt to access 2-codeunit String at index [4]
-Valid indices are between 1 and 1.
+Valid indices are 1.
 [...]
 
 julia> thisind("α", -1)
 ERROR: BoundsError: attempt to access 2-codeunit String at index [-1]
-Valid indices are between 1 and 1.
+Valid indices are 1.
 [...]
 ```
 """
@@ -485,7 +485,7 @@ julia> prevind("α", 1)
 
 julia> prevind("α", 0)
 ERROR: BoundsError: attempt to access 2-codeunit String at index [0]
-Valid indices are between 1 and 1.
+Valid indices are 1.
 [...]
 
 julia> prevind("α", 2, 2)
@@ -545,7 +545,7 @@ julia> nextind("α", 1)
 
 julia> nextind("α", 3)
 ERROR: BoundsError: attempt to access 2-codeunit String at index [3]
-Valid indices are between 1 and 1.
+Valid indices are 1.
 [...]
 
 julia> nextind("α", 0, 2)
diff --git a/base/strings/string.jl b/base/strings/string.jl
index 4becc9ccc4741..21fa8ac0728f1 100644
--- a/base/strings/string.jl
+++ b/base/strings/string.jl
@@ -27,13 +27,21 @@ function Base.showerror(io::IO, exc::StringIndexError)
     end
 end
 
-describe_valid_indices(io::IO, a::AbstractString, i=nothing) = print(io,
-                                                                     "\nValid indices are between ",
-                                                                     firstindex(a),
-                                                                     " and ",
-                                                                     thisind(a, ncodeunits(a)),
-                                                                     '.'
-                                                                    )
+function describe_valid_indices(io::IO, a::AbstractString, i=nothing)
+    firstind = firstindex(a)
+    lastind = thisind(a, ncodeunits(a))
+    if firstind == lastind
+        print(io, "\nValid indices are ", firstind, '.')
+        return
+    end
+    print(io,
+          "\nValid indices are between ",
+          firstindex(a),
+          " and ",
+          thisind(a, ncodeunits(a)),
+          '.'
+         )
+end
 
 const ByteArray = Union{CodeUnits{UInt8,String}, Vector{UInt8},Vector{Int8}, FastContiguousSubArray{UInt8,1,CodeUnits{UInt8,String}}, FastContiguousSubArray{UInt8,1,Vector{UInt8}}, FastContiguousSubArray{Int8,1,Vector{Int8}}}
 

From 2c880d6e86fac2d5e8a96dc5b69899d9e354c6ef Mon Sep 17 00:00:00 2001
From: David Gustavsson <david.e.gustavsson@gmail.com>
Date: Sat, 7 Jan 2023 16:39:12 +0100
Subject: [PATCH 11/12] Docstring typo

---
 doc/src/manual/interfaces.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/src/manual/interfaces.md b/doc/src/manual/interfaces.md
index 5a297eb1f0495..c5ac7f8fac7a3 100644
--- a/doc/src/manual/interfaces.md
+++ b/doc/src/manual/interfaces.md
@@ -424,7 +424,7 @@ above the maxima, but `A[0, 0]` will happily evaluate. If this is by intention,
 we can update the error message:
 
 ```jldoctest squarevectype
-julia> Base.describe_valid_indices(io::IO, A::SparseArray, i=nothing) = print(io, "Valid indices are <= ", A.dims, '.')
+julia> Base.describe_valid_indices(io::IO, A::SparseArray, i=nothing) = print(io, "\nValid indices are <= ", A.dims, '.')
 
 julia> A[0, 0]
 0.0

From 61b7d15d52d2e4e92b1900c5ca1a3decec73cf12 Mon Sep 17 00:00:00 2001
From: David Gustavsson <david.e.gustavsson@gmail.com>
Date: Sun, 8 Jan 2023 21:24:29 +0100
Subject: [PATCH 12/12] Fewer index hints, special-case 0

---
 base/abstractarray.jl          |  8 +++++---
 base/array.jl                  |  1 -
 base/docs/basedocs.jl          |  4 ----
 base/errorshow.jl              | 22 +++++-----------------
 base/essentials.jl             |  1 -
 base/strings/basic.jl          |  6 +-----
 base/strings/io.jl             |  2 +-
 base/strings/string.jl         | 11 ++---------
 base/tuple.jl                  |  6 +-----
 doc/src/manual/arrays.md       |  1 -
 doc/src/manual/interfaces.md   | 16 +++++++---------
 doc/src/manual/strings.md      |  4 +---
 stdlib/Dates/docs/src/index.md |  1 -
 stdlib/Test/test/runtests.jl   |  2 +-
 test/arrayops.jl               | 10 +++++-----
 test/errorshow.jl              | 12 ++++++------
 16 files changed, 35 insertions(+), 72 deletions(-)

diff --git a/base/abstractarray.jl b/base/abstractarray.jl
index 73ccbf533c8e9..36c6d55700544 100644
--- a/base/abstractarray.jl
+++ b/base/abstractarray.jl
@@ -744,9 +744,11 @@ checkbounds_indices(::Type{Bool}, ::Tuple{}, ::Tuple{}) = true
 throw_boundserror(A, I) = (@noinline; throw(BoundsError(A, I)))
 
 function describe_valid_indices(io::IO, a::AbstractArray{<:Any}, i=nothing)
-    print(io, "\nValid indices are ")
-    show_index(io, axes(a))
-    print(io, '.')
+    if any(x->!isa(x, OneTo), axes(a))
+        print(io, ", valid indices are ")
+        return show_index(io, axes(a))
+    end
+    any(iszero, i) && print(io, ", by default indices start from 1")
 end
 
 # check along a single dimension
diff --git a/base/array.jl b/base/array.jl
index f43e5cf35958e..694a3913cacf4 100644
--- a/base/array.jl
+++ b/base/array.jl
@@ -1365,7 +1365,6 @@ missing
 
 julia> popat!(a, 4)
 ERROR: BoundsError: attempt to access 3-element Vector{Int64} at index [4]
-Valid indices are 1:3.
 [...]
 ```
 """
diff --git a/base/docs/basedocs.jl b/base/docs/basedocs.jl
index 8833fa0423e3f..3e86095f181a9 100644
--- a/base/docs/basedocs.jl
+++ b/base/docs/basedocs.jl
@@ -401,7 +401,6 @@ Assignment at out-of-bounds indices does not grow a collection. If the collectio
 ```jldoctest
 julia> a = [1, 1]; a[3] = 2
 ERROR: BoundsError: attempt to access 2-element Array{Int64, 1} at index [3]
-Valid indices are 1:2.
 [...]
 
 julia> push!(a, 2, 3)
@@ -1676,19 +1675,16 @@ julia> A = fill(1.0, 7);
 
 julia> A[8]
 ERROR: BoundsError: attempt to access 7-element Vector{Float64} at index [8]
-Valid indices are 1:7.
 
 
 julia> B = fill(1.0, (2,3));
 
 julia> B[2, 4]
 ERROR: BoundsError: attempt to access 2×3 Matrix{Float64} at index [2, 4]
-Valid indices are [1:2, 1:3].
 
 
 julia> B[9]
 ERROR: BoundsError: attempt to access 2×3 Matrix{Float64} at index [9]
-Valid indices are [1:2, 1:3].
 
 ```
 """
diff --git a/base/errorshow.jl b/base/errorshow.jl
index 18d87ea9c3365..bbe4d4fcdbc58 100644
--- a/base/errorshow.jl
+++ b/base/errorshow.jl
@@ -32,17 +32,9 @@ showerror(io::IO, ex) = show(io, ex)
 show_index(io::IO, x::Any) = show(io, x)
 show_index(io::IO, x::Slice) = show_index(io, x.indices)
 show_index(io::IO, x::LogicalIndex) = summary(io, x.mask)
-function show_index(io::IO, x::OneTo)
-    if x.stop == 1
-        return print(io, '1')
-    end
-    print(io, "1:", x.stop)
-end
+show_index(io::IO, x::OneTo) = print(io, "1:", x.stop)
 show_index(io::IO, x::Colon) = print(io, ':')
 function show_index(io::IO, x::Tuple)
-    if length(x) == 1
-        return show_index(io, only(x))
-    end
     print(io, '[')
     show_index(io, first(x))
     for el in x[2:end]
@@ -76,12 +68,8 @@ function showerror(io::IO, ex::BoundsError)
 end
 
 Experimental.register_error_hint(BoundsError) do io, ex
-    if ~isdefined(ex, :a)
-        return print(io, "\nNo description of valid indices available.")
-    end
-    if isdefined(ex, :i)
-        return describe_valid_indices(io, ex.a, ex.i)
-    end
+    isdefined(ex, :a) || return nothing
+    isdefined(ex, :i) && return describe_valid_indices(io, ex.a, ex.i)
     describe_valid_indices(io, ex.a)
 end
 
@@ -89,11 +77,11 @@ end
     describe_valid_indices(io, a, i)
 
 Describe valid ways to index `a` in human-readable form. This should typically be a full
-sentence starting "\nValid indices are ". Will be shown to the user upon `BoundsError`.
+clause starting ", valid indices are ". Will be shown to the user upon `BoundsError`.
 
 `i` may be ignored, but could be used to determine what information to show.
 """
-describe_valid_indices(io::IO, a, i) = print(io, "\nNo description of valid indices available.")
+describe_valid_indices(io::IO, a, i) = nothing
 
 
 function showerror(io::IO, ex::TypeError)
diff --git a/base/essentials.jl b/base/essentials.jl
index 0b9da7088da95..2093c792dd9b4 100644
--- a/base/essentials.jl
+++ b/base/essentials.jl
@@ -608,7 +608,6 @@ julia> f2() = @inbounds return g(1:2, -1);
 
 julia> f1()
 ERROR: BoundsError: attempt to access 2-element UnitRange{Int64} at index [-1]
-Valid indices are 1:2.
 Stacktrace:
  [1] throw_boundserror(::UnitRange{Int64}, ::Tuple{Int64}) at ./abstractarray.jl:455
  [2] checkbounds at ./abstractarray.jl:420 [inlined]
diff --git a/base/strings/basic.jl b/base/strings/basic.jl
index d0ac8848c72e6..eecb80823eb9e 100644
--- a/base/strings/basic.jl
+++ b/base/strings/basic.jl
@@ -429,12 +429,10 @@ julia> thisind("α", 3)
 
 julia> thisind("α", 4)
 ERROR: BoundsError: attempt to access 2-codeunit String at index [4]
-Valid indices are 1.
 [...]
 
 julia> thisind("α", -1)
 ERROR: BoundsError: attempt to access 2-codeunit String at index [-1]
-Valid indices are 1.
 [...]
 ```
 """
@@ -484,8 +482,7 @@ julia> prevind("α", 1)
 0
 
 julia> prevind("α", 0)
-ERROR: BoundsError: attempt to access 2-codeunit String at index [0]
-Valid indices are 1.
+ERROR: BoundsError: attempt to access 2-codeunit String at index [0], by default indices start from 1
 [...]
 
 julia> prevind("α", 2, 2)
@@ -545,7 +542,6 @@ julia> nextind("α", 1)
 
 julia> nextind("α", 3)
 ERROR: BoundsError: attempt to access 2-codeunit String at index [3]
-Valid indices are 1.
 [...]
 
 julia> nextind("α", 0, 2)
diff --git a/base/strings/io.jl b/base/strings/io.jl
index 875b3b455a25f..e800002076d54 100644
--- a/base/strings/io.jl
+++ b/base/strings/io.jl
@@ -101,7 +101,7 @@ julia> sprint(show, 66.66666; context=:compact => true)
 "66.6667"
 
 julia> sprint(showerror, BoundsError([1], 100))
-"BoundsError: attempt to access 1-element Vector{Int64} at index [100]\\nValid indices are 1."
+"BoundsError: attempt to access 1-element Vector{Int64} at index [100]"
 ```
 """
 function sprint(f::Function, args...; context=nothing, sizehint::Integer=0)
diff --git a/base/strings/string.jl b/base/strings/string.jl
index 21fa8ac0728f1..2cef69d7aa64d 100644
--- a/base/strings/string.jl
+++ b/base/strings/string.jl
@@ -28,18 +28,11 @@ function Base.showerror(io::IO, exc::StringIndexError)
 end
 
 function describe_valid_indices(io::IO, a::AbstractString, i=nothing)
-    firstind = firstindex(a)
-    lastind = thisind(a, ncodeunits(a))
-    if firstind == lastind
-        print(io, "\nValid indices are ", firstind, '.')
-        return
-    end
     print(io,
-          "\nValid indices are between ",
+          ", valid indices are between ",
           firstindex(a),
           " and ",
-          thisind(a, ncodeunits(a)),
-          '.'
+          lastindex(a)
          )
 end
 
diff --git a/base/tuple.jl b/base/tuple.jl
index 0a06e66c083ce..ac83b0b01fa95 100644
--- a/base/tuple.jl
+++ b/base/tuple.jl
@@ -591,11 +591,7 @@ function sym_in(x::Symbol, @nospecialize itr::Tuple{Vararg{Symbol}})
 end
 in(x::Symbol, @nospecialize itr::Tuple{Vararg{Symbol}}) = sym_in(x, itr)
 
-function describe_valid_indices(io::IO, a::Tuple, i=nothing)
-    print(io, "\nValid indices are ")
-    show_index(io, axes(a))
-    print(io, '.')
-end
+describe_valid_indices(io::IO, a::Tuple, i=nothing) = iszero(i) && return print(io, ", tuple indices start from 1")
 
 """
     empty(x::Tuple)
diff --git a/doc/src/manual/arrays.md b/doc/src/manual/arrays.md
index 8462bfec05356..f9e60d83ff052 100644
--- a/doc/src/manual/arrays.md
+++ b/doc/src/manual/arrays.md
@@ -920,7 +920,6 @@ julia> A[1, 3, 2] # Omits the fourth dimension (length 1)
 
 julia> A[1, 3] # Attempts to omit dimensions 3 & 4 (lengths 2 and 1)
 ERROR: BoundsError: attempt to access 3×4×2×1 reshape(::UnitRange{Int64}, 3, 4, 2, 1) with eltype Int64 at index [1, 3]
-Valid indices are [1:3, 1:4, 1:2, 1].
 
 julia> A[19] # Linear indexing
 19
diff --git a/doc/src/manual/interfaces.md b/doc/src/manual/interfaces.md
index c5ac7f8fac7a3..9b41afaffac9a 100644
--- a/doc/src/manual/interfaces.md
+++ b/doc/src/manual/interfaces.md
@@ -402,10 +402,10 @@ perhaps range-types `Ind` of your own design. For more information, see
 [Arrays with custom indices](@ref man-custom-indices).
 
 When a user indexes into an array using an invalid index, a 'BoundsError' is
-thrown. Along with this error, a hint is printed telling the user which indices
-they *could* have used. If there is a more intuitive description of your type's
-valid indices than the default, which uses `axes(A)`, you can define a method
-to `describe_valid_indices(io::IO, A, i)`. If, for instance, we wanted to
+thrown. Along with this error, a hint can be printed telling the user which
+indices they *could* have used. If there is a more intuitive description of your
+type's valid indices than the default, which uses `axes(A)`, you can define a
+method to `describe_valid_indices(io::IO, A, i)`. If, for instance, we wanted to
 protect our `SparseArray` from bounds errors, we could redefine `getindex`:
 
 ```jldoctest squarevectype
@@ -416,22 +416,20 @@ julia> function Base.getindex(A::SparseArray{T,N}, I::Vararg{Int,N}) where {T,N}
 
 julia> A[4, 3]
 ERROR: BoundsError: attempt to access 3×3 SparseArray{Float64, 2} at index [4, 3]
-Valid indices are [1:3, 1:3].
 ```
 
-So far, this message is not entirely true. We implemented a check for indices
+This message could be made more informative. We implemented a check for indices
 above the maxima, but `A[0, 0]` will happily evaluate. If this is by intention,
 we can update the error message:
 
 ```jldoctest squarevectype
-julia> Base.describe_valid_indices(io::IO, A::SparseArray, i=nothing) = print(io, "\nValid indices are <= ", A.dims, '.')
+julia> Base.describe_valid_indices(io::IO, A::SparseArray, i=nothing) = print(io, ", valid indices are <= ", A.dims)
 
 julia> A[0, 0]
 0.0
 
 julia> A[4, 3]
-ERROR: BoundsError: attempt to access 3×3 SparseArray{Float64, 2} at index [4, 3]
-Valid indices are <= (3, 3).
+ERROR: BoundsError: attempt to access 3×3 SparseArray{Float64, 2} at index [4, 3], valid indices are <= (3, 3)
 ```
 
 ## [Strided Arrays](@id man-interface-strided-arrays)
diff --git a/doc/src/manual/strings.md b/doc/src/manual/strings.md
index add6403186851..674a8c79fa406 100644
--- a/doc/src/manual/strings.md
+++ b/doc/src/manual/strings.md
@@ -213,13 +213,11 @@ Using an index less than `begin` (`1`) or greater than `end` raises an error:
 
 ```jldoctest helloworldstring
 julia> str[begin-1]
-ERROR: BoundsError: attempt to access 14-codeunit String at index [0]
-Valid indices are between 1 and 14.
+ERROR: BoundsError: attempt to access 14-codeunit String at index [0], valid indices are between 1 and 14
 [...]
 
 julia> str[end+1]
 ERROR: BoundsError: attempt to access 14-codeunit String at index [15]
-Valid indices are between 1 and 14.
 [...]
 ```
 
diff --git a/stdlib/Dates/docs/src/index.md b/stdlib/Dates/docs/src/index.md
index c2d355daa36ab..e0e09a919a085 100644
--- a/stdlib/Dates/docs/src/index.md
+++ b/stdlib/Dates/docs/src/index.md
@@ -366,7 +366,6 @@ function `dayabbr` will throw an error.
 ```jldoctest tdate2
 julia> Dates.dayabbr(t;locale="french")
 ERROR: BoundsError: attempt to access 1-element Vector{String} at index [5]
-Valid indices are 1.
 Stacktrace:
 [...]
 ```
diff --git a/stdlib/Test/test/runtests.jl b/stdlib/Test/test/runtests.jl
index 265fa8bbbcde0..ac643e0ccfca2 100644
--- a/stdlib/Test/test/runtests.jl
+++ b/stdlib/Test/test/runtests.jl
@@ -103,7 +103,7 @@ end
     @test endswith(sprint(show, @test_throws str->occursin("a t", str) error("a test")),
                    "Message: \"a test\"")
     @test endswith(sprint(show, @test_throws ["BoundsError", "access", "1-element", "at index [2]"] [1][2]),
-                   "Message: \"BoundsError: attempt to access 1-element Vector{$Int} at index [2]\\nValid indices are 1.\"")
+                   "Message: \"BoundsError: attempt to access 1-element Vector{$Int} at index [2]\"")
     @test_throws "\"" throw("\"")
     @test_throws Returns(false) throw(Returns(false))
 end
diff --git a/test/arrayops.jl b/test/arrayops.jl
index fbb4b183edb52..e7ac6a1132568 100644
--- a/test/arrayops.jl
+++ b/test/arrayops.jl
@@ -3020,29 +3020,29 @@ end
     b = IOBuffer()
     showerror(b, err)
     @test String(take!(b)) ==
-        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, 1:2]\nValid indices are [1:2, 1:2]."
+        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, 1:2]"
 
     err = try x[10, trues(2)]; catch err; err; end
     b = IOBuffer()
     showerror(b, err)
     @test String(take!(b)) ==
-        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, 2-element BitVector]\nValid indices are [1:2, 1:2]."
+        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, 2-element BitVector]"
 
     # Also test : directly for custom types for which it may appear as-is
     err = BoundsError(x, (10, :))
     showerror(b, err)
     @test String(take!(b)) ==
-        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, :]\nValid indices are [1:2, 1:2]."
+        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, :]"
 
     err = BoundsError(x, "bad index")
     showerror(b, err)
     @test String(take!(b)) ==
-        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [\"bad index\"]\nValid indices are [1:2, 1:2]."
+        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [\"bad index\"]"
 
     err = BoundsError(x, (10, "bad index"))
     showerror(b, err)
     @test String(take!(b)) ==
-        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, \"bad index\"]\nValid indices are [1:2, 1:2]."
+        "BoundsError: attempt to access 2×2 Matrix{Float64} at index [10, \"bad index\"]"
 end
 
 @testset "inference of Union{T,Nothing} arrays 26771" begin
diff --git a/test/errorshow.jl b/test/errorshow.jl
index f8845e1459047..bd9e3b1608901 100644
--- a/test/errorshow.jl
+++ b/test/errorshow.jl
@@ -289,7 +289,7 @@ struct Bounded  # not an AbstractArray
 end
 Base.getindex(b::Bounded, i) = checkindex(Bool, 1:b.bound, i) || throw(BoundsError(b, i))
 Base.summary(io::IO, b::Bounded) = print(io, "$(b.bound)-size Bounded")
-Base.describe_valid_indices(io::IO, b::Bounded, i=nothing) = print(io, "\nValid indices are 1:$(b.bound).")
+Base.describe_valid_indices(io::IO, b::Bounded, i=nothing) = print(io, ", valid indices are 1:$(b.bound)")
 let undefvar
     err_str = @except_strbt sqrt(-1) DomainError
     @test occursin("Try sqrt(Complex(x)).", err_str)
@@ -304,17 +304,17 @@ let undefvar
     @test occursin("DomainError with [0.0 -1.0 …", err_str)
 
     err_str = @except_str (1, 2, 3)[4] BoundsError
-    @test err_str == "BoundsError: attempt to access Tuple{$Int, $Int, $Int} at index [4]\nValid indices are 1:3."
+    @test err_str == "BoundsError: attempt to access Tuple{$Int, $Int, $Int} at index [4]"
 
     err_str = @except_str [5, 4, 3][-2, 1] BoundsError
-    @test err_str == "BoundsError: attempt to access 3-element Vector{$Int} at index [-2, 1]\nValid indices are 1:3."
+    @test err_str == "BoundsError: attempt to access 3-element Vector{$Int} at index [-2, 1]"
     err_str = @except_str [5, 4, 3][1:5] BoundsError
-    @test err_str == "BoundsError: attempt to access 3-element Vector{$Int} at index [1:5]\nValid indices are 1:3."
+    @test err_str == "BoundsError: attempt to access 3-element Vector{$Int} at index [1:5]"
     err_str = @except_str [5, 4, 3][trues(6,7)] BoundsError
-    @test err_str == "BoundsError: attempt to access 3-element Vector{$Int} at index [6×7 BitMatrix]\nValid indices are 1:3."
+    @test err_str == "BoundsError: attempt to access 3-element Vector{$Int} at index [6×7 BitMatrix]"
 
     err_str = @except_str Bounded(2)[3] BoundsError
-    @test err_str == "BoundsError: attempt to access 2-size Bounded at index [3]\nValid indices are 1:2."
+    @test err_str == "BoundsError: attempt to access 2-size Bounded at index [3], valid indices are 1:2"
 
     err_str = @except_str 0::Bool TypeError
     @test err_str == "TypeError: non-boolean ($Int) used in boolean context"