Evaluate std::fmt::Arguments::new_const() During Compile Time

Author: veera-sivarajan

compiler/rustc_ast_lowering/src/format.rs

@@ -5,6 +5,7 @@ use rustc_ast::visit::Visitor;
 use rustc_ast::*;
 use rustc_data_structures::fx::FxIndexMap;
 use rustc_hir as hir;
+use rustc_hir::def::DefKind;
 use rustc_session::config::FmtDebug;
 use rustc_span::symbol::{Ident, kw};
 use rustc_span::{Span, Symbol, sym};
@@ -24,6 +25,28 @@ impl<'hir> LoweringContext<'_, 'hir> {
         expand_format_args(self, sp, &fmt, allow_const)
     }
 
+    /// Wraps given `ExprKind` in an inline const block.
+    ///
+    /// Caller must ensure it's safe and sound to do so.
+    fn wrap_in_const_context(
+        &mut self,
+        sp: Span,
+        kind: hir::ExprKind<'hir>,
+    ) -> hir::ExprKind<'hir> {
+        let expr = hir::Expr { hir_id: self.next_id(), kind, span: self.lower_span(sp) };
+        let const_node_id = self.next_node_id();
+        let parent_def_id = self.current_def_id_parent;
+        let def_id =
+            self.create_def(parent_def_id, const_node_id, kw::Empty, DefKind::InlineConst, sp);
+        let hir_id = self.lower_node_id(const_node_id);
+        let const_block = self.with_new_scopes(sp, |this| hir::ConstBlock {
+            def_id,
+            hir_id,
+            body: this.with_def_id_parent(def_id, |this| this.lower_body(|_| (&[], expr))),
+        });
+        hir::ExprKind::ConstBlock(const_block)
+    }
+
     /// Try to convert a literal into an interned string
     fn try_inline_lit(&self, lit: token::Lit) -> Option<Symbol> {
         match LitKind::from_token_lit(lit) {
@@ -464,14 +487,14 @@ fn expand_format_args<'hir>(
 
     if allow_const && arguments.is_empty() && argmap.is_empty() {
         // Generate:
-        //     <core::fmt::Arguments>::new_const(lit_pieces)
+        //    const { <core::fmt::Arguments>::new_const(lit_pieces) }
         let new = ctx.arena.alloc(ctx.expr_lang_item_type_relative(
             macsp,
             hir::LangItem::FormatArguments,
             sym::new_const,
         ));
         let new_args = ctx.arena.alloc_from_iter([lit_pieces]);
-        return hir::ExprKind::Call(new, new_args);
+        return ctx.wrap_in_const_context(macsp, hir::ExprKind::Call(new, new_args));
     }
 
     // If the args array contains exactly all the original arguments once,

library/core/src/fmt/mod.rs

@@ -333,7 +333,7 @@ pub struct Arguments<'a> {
 #[unstable(feature = "fmt_internals", issue = "none")]
 impl<'a> Arguments<'a> {
     #[inline]
-    #[rustc_const_unstable(feature = "const_fmt_arguments_new", issue = "none")]
+    #[rustc_const_stable(feature = "const_fmt_arguments_new", since = "CURRENT_RUSTC_VERSION")]
     pub const fn new_const<const N: usize>(pieces: &'a [&'static str; N]) -> Self {
         const { assert!(N <= 1) };
         Arguments { pieces, fmt: None, args: &[] }

library/core/src/lib.rs

@@ -120,7 +120,6 @@
 #![feature(const_char_encode_utf16)]
 #![feature(const_eval_select)]
 #![feature(const_exact_div)]
-#![feature(const_fmt_arguments_new)]
 #![feature(const_hash)]
 #![feature(const_heap)]
 #![feature(const_index_range_slice_index)]

library/core/src/macros/mod.rs

@@ -1038,7 +1038,7 @@ pub(crate) mod builtin {
     ///
     /// This macro will be removed once `format_args` is allowed in const contexts.
     #[unstable(feature = "const_format_args", issue = "none")]
-    #[allow_internal_unstable(fmt_internals, const_fmt_arguments_new)]
+    #[allow_internal_unstable(fmt_internals)]
     #[rustc_builtin_macro]
     #[macro_export]
     macro_rules! const_format_args {

tests/codegen/issues/issue-128709-format-without-args.rs

@@ -3,7 +3,7 @@
 #![crate_type = "lib"]
 
 // String formating macros without any arguments should compile
-// to a `memcpy` followed by a call to `std::io::stdio::_print`.
+// to a `memcpy` followed by a call to a library function.
 
 #[no_mangle]
 pub fn code() {

tests/coverage/assert.cov-map

@@ -28,15 +28,12 @@ Number of file 0 mappings: 9
 Highest counter ID seen: c4
 
 Function name: assert::might_fail_assert
-Raw bytes (21): 0x[01, 01, 01, 01, 05, 03, 01, 04, 01, 02, 0f, 02, 02, 25, 00, 3d, 05, 01, 01, 00, 02]
+Raw bytes (14): 0x[01, 01, 00, 02, 01, 04, 01, 02, 3e, 05, 03, 01, 00, 02]
 Number of files: 1
 - file 0 => global file 1
-Number of expressions: 1
-- expression 0 operands: lhs = Counter(0), rhs = Counter(1)
-Number of file 0 mappings: 3
-- Code(Counter(0)) at (prev + 4, 1) to (start + 2, 15)
-- Code(Expression(0, Sub)) at (prev + 2, 37) to (start + 0, 61)
-    = (c0 - c1)
-- Code(Counter(1)) at (prev + 1, 1) to (start + 0, 2)
+Number of expressions: 0
+Number of file 0 mappings: 2
+- Code(Counter(0)) at (prev + 4, 1) to (start + 2, 62)
+- Code(Counter(1)) at (prev + 3, 1) to (start + 0, 2)
 Highest counter ID seen: c1
 

tests/coverage/bad_counter_ids.cov-map

@@ -9,16 +9,13 @@ Number of file 0 mappings: 2
 Highest counter ID seen: c0
 
 Function name: bad_counter_ids::eq_bad_message
-Raw bytes (21): 0x[01, 01, 01, 01, 00, 03, 01, 29, 01, 02, 0f, 02, 02, 20, 00, 2b, 00, 01, 01, 00, 02]
+Raw bytes (14): 0x[01, 01, 00, 02, 01, 29, 01, 02, 2c, 00, 03, 01, 00, 02]
 Number of files: 1
 - file 0 => global file 1
-Number of expressions: 1
-- expression 0 operands: lhs = Counter(0), rhs = Zero
-Number of file 0 mappings: 3
-- Code(Counter(0)) at (prev + 41, 1) to (start + 2, 15)
-- Code(Expression(0, Sub)) at (prev + 2, 32) to (start + 0, 43)
-    = (c0 - Zero)
-- Code(Zero) at (prev + 1, 1) to (start + 0, 2)
+Number of expressions: 0
+Number of file 0 mappings: 2
+- Code(Counter(0)) at (prev + 41, 1) to (start + 2, 44)
+- Code(Zero) at (prev + 3, 1) to (start + 0, 2)
 Highest counter ID seen: c0
 
 Function name: bad_counter_ids::eq_good
@@ -32,14 +29,13 @@ Number of file 0 mappings: 2
 Highest counter ID seen: c1
 
 Function name: bad_counter_ids::eq_good_message
-Raw bytes (19): 0x[01, 01, 00, 03, 01, 15, 01, 02, 0f, 00, 02, 20, 00, 2b, 05, 01, 01, 00, 02]
+Raw bytes (14): 0x[01, 01, 00, 02, 01, 15, 01, 02, 2c, 05, 03, 01, 00, 02]
 Number of files: 1
 - file 0 => global file 1
 Number of expressions: 0
-Number of file 0 mappings: 3
-- Code(Counter(0)) at (prev + 21, 1) to (start + 2, 15)
-- Code(Zero) at (prev + 2, 32) to (start + 0, 43)
-- Code(Counter(1)) at (prev + 1, 1) to (start + 0, 2)
+Number of file 0 mappings: 2
+- Code(Counter(0)) at (prev + 21, 1) to (start + 2, 44)
+- Code(Counter(1)) at (prev + 3, 1) to (start + 0, 2)
 Highest counter ID seen: c1
 
 Function name: bad_counter_ids::ne_bad
@@ -53,15 +49,14 @@ Number of file 0 mappings: 2
 Highest counter ID seen: c0
 
 Function name: bad_counter_ids::ne_bad_message
-Raw bytes (19): 0x[01, 01, 00, 03, 01, 33, 01, 02, 0f, 05, 02, 20, 00, 2b, 00, 01, 01, 00, 02]
+Raw bytes (14): 0x[01, 01, 00, 02, 01, 33, 01, 02, 2c, 00, 03, 01, 00, 02]
 Number of files: 1
 - file 0 => global file 1
 Number of expressions: 0
-Number of file 0 mappings: 3
-- Code(Counter(0)) at (prev + 51, 1) to (start + 2, 15)
-- Code(Counter(1)) at (prev + 2, 32) to (start + 0, 43)
-- Code(Zero) at (prev + 1, 1) to (start + 0, 2)
-Highest counter ID seen: c1
+Number of file 0 mappings: 2
+- Code(Counter(0)) at (prev + 51, 1) to (start + 2, 44)
+- Code(Zero) at (prev + 3, 1) to (start + 0, 2)
+Highest counter ID seen: c0
 
 Function name: bad_counter_ids::ne_good
 Raw bytes (16): 0x[01, 01, 01, 01, 00, 02, 01, 1a, 01, 02, 1f, 02, 03, 01, 00, 02]
@@ -76,15 +71,14 @@ Number of file 0 mappings: 2
 Highest counter ID seen: c0
 
 Function name: bad_counter_ids::ne_good_message
-Raw bytes (21): 0x[01, 01, 01, 01, 00, 03, 01, 1f, 01, 02, 0f, 00, 02, 20, 00, 2b, 02, 01, 01, 00, 02]
+Raw bytes (16): 0x[01, 01, 01, 01, 00, 02, 01, 1f, 01, 02, 2c, 02, 03, 01, 00, 02]
 Number of files: 1
 - file 0 => global file 1
 Number of expressions: 1
 - expression 0 operands: lhs = Counter(0), rhs = Zero
-Number of file 0 mappings: 3
-- Code(Counter(0)) at (prev + 31, 1) to (start + 2, 15)
-- Code(Zero) at (prev + 2, 32) to (start + 0, 43)
-- Code(Expression(0, Sub)) at (prev + 1, 1) to (start + 0, 2)
+Number of file 0 mappings: 2
+- Code(Counter(0)) at (prev + 31, 1) to (start + 2, 44)
+- Code(Expression(0, Sub)) at (prev + 3, 1) to (start + 0, 2)
     = (c0 - Zero)
 Highest counter ID seen: c0
 

tests/coverage/closure_macro.cov-map

@@ -25,20 +25,19 @@ Number of file 0 mappings: 6
 Highest counter ID seen: c1
 
 Function name: closure_macro::main::{closure#0}
-Raw bytes (35): 0x[01, 01, 03, 01, 05, 05, 0b, 09, 0d, 05, 01, 10, 1c, 03, 21, 05, 04, 11, 01, 27, 02, 03, 11, 00, 16, 0d, 00, 17, 00, 1e, 07, 02, 09, 00, 0a]
+Raw bytes (30): 0x[01, 01, 03, 01, 05, 05, 0b, 09, 0d, 04, 01, 10, 1c, 03, 21, 05, 04, 11, 01, 27, 02, 03, 11, 00, 1f, 07, 02, 09, 00, 0a]
 Number of files: 1
 - file 0 => global file 1
 Number of expressions: 3
 - expression 0 operands: lhs = Counter(0), rhs = Counter(1)
 - expression 1 operands: lhs = Counter(1), rhs = Expression(2, Add)
 - expression 2 operands: lhs = Counter(2), rhs = Counter(3)
-Number of file 0 mappings: 5
+Number of file 0 mappings: 4
 - Code(Counter(0)) at (prev + 16, 28) to (start + 3, 33)
 - Code(Counter(1)) at (prev + 4, 17) to (start + 1, 39)
-- Code(Expression(0, Sub)) at (prev + 3, 17) to (start + 0, 22)
+- Code(Expression(0, Sub)) at (prev + 3, 17) to (start + 0, 31)
     = (c0 - c1)
-- Code(Counter(3)) at (prev + 0, 23) to (start + 0, 30)
 - Code(Expression(1, Add)) at (prev + 2, 9) to (start + 0, 10)
     = (c1 + (c2 + c3))
-Highest counter ID seen: c3
+Highest counter ID seen: c1
 

tests/coverage/closure_macro_async.cov-map

@@ -34,20 +34,19 @@ Number of file 0 mappings: 6
 Highest counter ID seen: c1
 
 Function name: closure_macro_async::test::{closure#0}::{closure#0}
-Raw bytes (35): 0x[01, 01, 03, 01, 05, 05, 0b, 09, 0d, 05, 01, 15, 1c, 03, 21, 05, 04, 11, 01, 27, 02, 03, 11, 00, 16, 0d, 00, 17, 00, 1e, 07, 02, 09, 00, 0a]
+Raw bytes (30): 0x[01, 01, 03, 01, 05, 05, 0b, 09, 0d, 04, 01, 15, 1c, 03, 21, 05, 04, 11, 01, 27, 02, 03, 11, 00, 1f, 07, 02, 09, 00, 0a]
 Number of files: 1
 - file 0 => global file 1
 Number of expressions: 3
 - expression 0 operands: lhs = Counter(0), rhs = Counter(1)
 - expression 1 operands: lhs = Counter(1), rhs = Expression(2, Add)
 - expression 2 operands: lhs = Counter(2), rhs = Counter(3)
-Number of file 0 mappings: 5
+Number of file 0 mappings: 4
 - Code(Counter(0)) at (prev + 21, 28) to (start + 3, 33)
 - Code(Counter(1)) at (prev + 4, 17) to (start + 1, 39)
-- Code(Expression(0, Sub)) at (prev + 3, 17) to (start + 0, 22)
+- Code(Expression(0, Sub)) at (prev + 3, 17) to (start + 0, 31)
     = (c0 - c1)
-- Code(Counter(3)) at (prev + 0, 23) to (start + 0, 30)
 - Code(Expression(1, Add)) at (prev + 2, 9) to (start + 0, 10)
     = (c1 + (c2 + c3))
-Highest counter ID seen: c3
+Highest counter ID seen: c1
 

tests/coverage/issue-84561.cov-map

@@ -22,32 +22,27 @@ Number of file 0 mappings: 1
 Highest counter ID seen: c0
 
 Function name: issue_84561::test1
-Raw bytes (50): 0x[01, 01, 00, 09, 01, 9a, 01, 01, 01, 0b, 05, 01, 0c, 00, 1e, 01, 01, 05, 00, 0b, 09, 00, 0c, 00, 1e, 01, 01, 0d, 01, 0b, 0d, 01, 0c, 00, 1e, 01, 01, 05, 03, 0b, 11, 03, 0c, 00, 1e, 01, 01, 01, 00, 02]
+Raw bytes (30): 0x[01, 01, 00, 05, 01, 9a, 01, 01, 01, 1f, 01, 02, 05, 00, 1f, 01, 01, 0d, 01, 1f, 01, 02, 05, 03, 1f, 01, 04, 01, 00, 02]
 Number of files: 1
 - file 0 => global file 1
 Number of expressions: 0
-Number of file 0 mappings: 9
-- Code(Counter(0)) at (prev + 154, 1) to (start + 1, 11)
-- Code(Counter(1)) at (prev + 1, 12) to (start + 0, 30)
-- Code(Counter(0)) at (prev + 1, 5) to (start + 0, 11)
-- Code(Counter(2)) at (prev + 0, 12) to (start + 0, 30)
-- Code(Counter(0)) at (prev + 1, 13) to (start + 1, 11)
-- Code(Counter(3)) at (prev + 1, 12) to (start + 0, 30)
-- Code(Counter(0)) at (prev + 1, 5) to (start + 3, 11)
-- Code(Counter(4)) at (prev + 3, 12) to (start + 0, 30)
-- Code(Counter(0)) at (prev + 1, 1) to (start + 0, 2)
-Highest counter ID seen: c4
+Number of file 0 mappings: 5
+- Code(Counter(0)) at (prev + 154, 1) to (start + 1, 31)
+- Code(Counter(0)) at (prev + 2, 5) to (start + 0, 31)
+- Code(Counter(0)) at (prev + 1, 13) to (start + 1, 31)
+- Code(Counter(0)) at (prev + 2, 5) to (start + 3, 31)
+- Code(Counter(0)) at (prev + 4, 1) to (start + 0, 2)
+Highest counter ID seen: c0
 
 Function name: issue_84561::test2
-Raw bytes (20): 0x[01, 01, 00, 03, 01, b0, 01, 01, 01, 10, 05, 01, 11, 00, 23, 01, 01, 01, 00, 02]
+Raw bytes (15): 0x[01, 01, 00, 02, 01, b0, 01, 01, 01, 24, 01, 02, 01, 00, 02]
 Number of files: 1
 - file 0 => global file 1
 Number of expressions: 0
-Number of file 0 mappings: 3
-- Code(Counter(0)) at (prev + 176, 1) to (start + 1, 16)
-- Code(Counter(1)) at (prev + 1, 17) to (start + 0, 35)
-- Code(Counter(0)) at (prev + 1, 1) to (start + 0, 2)
-Highest counter ID seen: c1
+Number of file 0 mappings: 2
+- Code(Counter(0)) at (prev + 176, 1) to (start + 1, 36)
+- Code(Counter(0)) at (prev + 2, 1) to (start + 0, 2)
+Highest counter ID seen: c0
 
 Function name: issue_84561::test2::call_print
 Raw bytes (10): 0x[01, 01, 00, 01, 01, a7, 01, 09, 02, 0a]
@@ -59,10 +54,10 @@ Number of file 0 mappings: 1
 Highest counter ID seen: c0
 
 Function name: issue_84561::test3
-Raw bytes (375): 0x[01, 01, 31, 05, 09, 0d, 00, 15, 19, 12, 00, 15, 19, 21, 00, 1e, 00, 21, 00, 31, 00, 3d, 00, 2e, 45, 3d, 00, 42, 49, 45, 00, 3f, 51, 42, 49, 45, 00, 7a, 55, 51, 00, 7a, 55, 51, 00, 77, 5d, 7a, 55, 51, 00, 77, 61, 7a, 55, 51, 00, 72, 65, 77, 61, 7a, 55, 51, 00, 75, be, 01, c2, 01, 79, 69, 6d, 69, 6d, 69, 6d, c2, 01, 00, 69, 6d, c2, 01, 79, 69, 6d, bb, 01, 7d, 75, be, 01, c2, 01, 79, 69, 6d, b6, 01, 00, bb, 01, 7d, 75, be, 01, c2, 01, 79, 69, 6d, 33, 01, 08, 01, 03, 1c, 05, 04, 09, 01, 1c, 02, 02, 05, 04, 1f, 0d, 05, 05, 00, 1f, 06, 01, 05, 00, 1f, 15, 01, 09, 01, 1c, 12, 02, 05, 00, 1f, 0e, 01, 05, 00, 0f, 00, 00, 20, 00, 30, 21, 01, 05, 03, 0f, 00, 03, 20, 00, 30, 00, 00, 33, 00, 41, 00, 00, 4b, 00, 5a, 1e, 01, 05, 00, 0f, 00, 05, 09, 03, 10, 00, 05, 0d, 00, 1b, 00, 02, 0d, 00, 1c, 1a, 04, 09, 05, 06, 31, 06, 05, 03, 06, 22, 04, 05, 03, 06, 3d, 04, 09, 04, 06, 2e, 05, 08, 00, 0f, 45, 01, 09, 03, 0a, 2a, 05, 09, 03, 0a, 3f, 05, 08, 00, 0f, 51, 01, 09, 00, 13, 00, 03, 0d, 00, 1d, 3a, 03, 09, 00, 13, 00, 03, 0d, 00, 1d, 77, 03, 05, 00, 0f, 77, 01, 0c, 00, 13, 5d, 01, 0d, 00, 13, 56, 02, 0d, 00, 13, 72, 04, 05, 02, 13, 65, 03, 0d, 00, 13, 6e, 02, 0d, 00, 13, bb, 01, 03, 05, 00, 0f, 69, 01, 0c, 00, 13, 6d, 01, 0d, 03, 0e, 75, 04, 0d, 00, 13, c2, 01, 02, 0d, 00, 17, c2, 01, 01, 14, 00, 1b, 00, 01, 15, 00, 1b, 92, 01, 02, 15, 00, 1b, be, 01, 04, 0d, 00, 13, 7d, 03, 09, 00, 19, b6, 01, 02, 05, 00, 0f, b2, 01, 03, 09, 00, 22, 00, 02, 05, 00, 0f, 00, 03, 09, 00, 2c, 00, 02, 01, 00, 02]
+Raw bytes (330): 0x[01, 01, 2c, 05, 09, 0d, 00, 15, 19, 12, 00, 15, 19, 21, 00, 1e, 00, 21, 00, 31, 00, 3d, 00, 2e, 45, 3d, 00, 42, 49, 45, 00, 3f, 51, 42, 49, 45, 00, 7a, 55, 51, 00, 7a, 55, 51, 00, 77, 5d, 7a, 55, 51, 00, 77, 61, 7a, 55, 51, 00, 72, 65, 77, 61, 7a, 55, 51, 00, 75, aa, 01, ae, 01, 79, 69, 6d, 69, 6d, 69, 6d, ae, 01, 00, 69, 6d, ae, 01, 79, 69, 6d, a7, 01, 7d, 75, aa, 01, ae, 01, 79, 69, 6d, 2d, 01, 08, 01, 03, 1c, 05, 04, 09, 01, 1c, 02, 02, 05, 04, 1f, 0d, 05, 05, 00, 1f, 06, 01, 05, 00, 1f, 15, 01, 09, 01, 1c, 12, 02, 05, 00, 1f, 0e, 01, 05, 00, 31, 21, 01, 05, 03, 0f, 00, 03, 20, 00, 30, 00, 00, 33, 00, 41, 00, 00, 4b, 00, 5a, 1e, 01, 05, 00, 0f, 00, 05, 09, 03, 10, 00, 05, 0d, 00, 1b, 00, 02, 0d, 00, 1c, 1a, 04, 09, 05, 06, 31, 06, 05, 03, 06, 22, 04, 05, 03, 06, 3d, 04, 09, 04, 06, 2e, 05, 08, 00, 0f, 45, 01, 09, 03, 0a, 2a, 05, 09, 03, 0a, 3f, 05, 08, 00, 0f, 51, 01, 09, 04, 0a, 3a, 06, 09, 04, 0a, 77, 06, 05, 00, 0f, 77, 01, 0c, 00, 13, 5d, 01, 0d, 00, 13, 56, 02, 0d, 00, 13, 72, 04, 05, 02, 13, 65, 03, 0d, 00, 13, 6e, 02, 0d, 00, 13, a7, 01, 03, 05, 00, 0f, 69, 01, 0c, 00, 13, 6d, 01, 0d, 03, 0e, 75, 04, 0d, 00, 13, ae, 01, 02, 0d, 00, 17, ae, 01, 01, 14, 00, 1b, 00, 01, 15, 00, 1b, 92, 01, 02, 15, 00, 1b, aa, 01, 04, 0d, 00, 13, a2, 01, 05, 05, 04, 06, 00, 05, 05, 04, 06, 00, 05, 01, 00, 02]
 Number of files: 1
 - file 0 => global file 1
-Number of expressions: 49
+Number of expressions: 44
 - expression 0 operands: lhs = Counter(1), rhs = Counter(2)
 - expression 1 operands: lhs = Counter(3), rhs = Zero
 - expression 2 operands: lhs = Counter(5), rhs = Counter(6)
@@ -94,25 +89,20 @@ Number of expressions: 49
 - expression 28 operands: lhs = Expression(29, Add), rhs = Counter(24)
 - expression 29 operands: lhs = Expression(30, Sub), rhs = Counter(21)
 - expression 30 operands: lhs = Counter(20), rhs = Zero
-- expression 31 operands: lhs = Counter(29), rhs = Expression(47, Sub)
-- expression 32 operands: lhs = Expression(48, Sub), rhs = Counter(30)
+- expression 31 operands: lhs = Counter(29), rhs = Expression(42, Sub)
+- expression 32 operands: lhs = Expression(43, Sub), rhs = Counter(30)
 - expression 33 operands: lhs = Counter(26), rhs = Counter(27)
 - expression 34 operands: lhs = Counter(26), rhs = Counter(27)
 - expression 35 operands: lhs = Counter(26), rhs = Counter(27)
-- expression 36 operands: lhs = Expression(48, Sub), rhs = Zero
+- expression 36 operands: lhs = Expression(43, Sub), rhs = Zero
 - expression 37 operands: lhs = Counter(26), rhs = Counter(27)
-- expression 38 operands: lhs = Expression(48, Sub), rhs = Counter(30)
+- expression 38 operands: lhs = Expression(43, Sub), rhs = Counter(30)
 - expression 39 operands: lhs = Counter(26), rhs = Counter(27)
-- expression 40 operands: lhs = Expression(46, Add), rhs = Counter(31)
-- expression 41 operands: lhs = Counter(29), rhs = Expression(47, Sub)
-- expression 42 operands: lhs = Expression(48, Sub), rhs = Counter(30)
+- expression 40 operands: lhs = Expression(41, Add), rhs = Counter(31)
+- expression 41 operands: lhs = Counter(29), rhs = Expression(42, Sub)
+- expression 42 operands: lhs = Expression(43, Sub), rhs = Counter(30)
 - expression 43 operands: lhs = Counter(26), rhs = Counter(27)
-- expression 44 operands: lhs = Expression(45, Sub), rhs = Zero
-- expression 45 operands: lhs = Expression(46, Add), rhs = Counter(31)
-- expression 46 operands: lhs = Counter(29), rhs = Expression(47, Sub)
-- expression 47 operands: lhs = Expression(48, Sub), rhs = Counter(30)
-- expression 48 operands: lhs = Counter(26), rhs = Counter(27)
-Number of file 0 mappings: 51
+Number of file 0 mappings: 45
 - Code(Counter(0)) at (prev + 8, 1) to (start + 3, 28)
 - Code(Counter(1)) at (prev + 4, 9) to (start + 1, 28)
 - Code(Expression(0, Sub)) at (prev + 2, 5) to (start + 4, 31)
@@ -123,9 +113,8 @@ Number of file 0 mappings: 51
 - Code(Counter(5)) at (prev + 1, 9) to (start + 1, 28)
 - Code(Expression(4, Sub)) at (prev + 2, 5) to (start + 0, 31)
     = (c5 - c6)
-- Code(Expression(3, Sub)) at (prev + 1, 5) to (start + 0, 15)
+- Code(Expression(3, Sub)) at (prev + 1, 5) to (start + 0, 49)
     = ((c5 - c6) - Zero)
-- Code(Zero) at (prev + 0, 32) to (start + 0, 48)
 - Code(Counter(8)) at (prev + 1, 5) to (start + 3, 15)
 - Code(Zero) at (prev + 3, 32) to (start + 0, 48)
 - Code(Zero) at (prev + 0, 51) to (start + 0, 65)
@@ -148,12 +137,10 @@ Number of file 0 mappings: 51
     = ((c15 - Zero) - c17)
 - Code(Expression(15, Add)) at (prev + 5, 8) to (start + 0, 15)
     = ((c17 - Zero) + c18)
-- Code(Counter(20)) at (prev + 1, 9) to (start + 0, 19)
-- Code(Zero) at (prev + 3, 13) to (start + 0, 29)
-- Code(Expression(14, Sub)) at (prev + 3, 9) to (start + 0, 19)
+- Code(Counter(20)) at (prev + 1, 9) to (start + 4, 10)
+- Code(Expression(14, Sub)) at (prev + 6, 9) to (start + 4, 10)
     = (((c17 - Zero) + c18) - c20)
-- Code(Zero) at (prev + 3, 13) to (start + 0, 29)
-- Code(Expression(29, Add)) at (prev + 3, 5) to (start + 0, 15)
+- Code(Expression(29, Add)) at (prev + 6, 5) to (start + 0, 15)
     = ((c20 - Zero) + c21)
 - Code(Expression(29, Add)) at (prev + 1, 12) to (start + 0, 19)
     = ((c20 - Zero) + c21)
@@ -165,27 +152,23 @@ Number of file 0 mappings: 51
 - Code(Counter(25)) at (prev + 3, 13) to (start + 0, 19)
 - Code(Expression(27, Sub)) at (prev + 2, 13) to (start + 0, 19)
     = ((((c20 - Zero) + c21) - c24) - c25)
-- Code(Expression(46, Add)) at (prev + 3, 5) to (start + 0, 15)
+- Code(Expression(41, Add)) at (prev + 3, 5) to (start + 0, 15)
     = (c29 + ((c26 - c27) - c30))
 - Code(Counter(26)) at (prev + 1, 12) to (start + 0, 19)
 - Code(Counter(27)) at (prev + 1, 13) to (start + 3, 14)
 - Code(Counter(29)) at (prev + 4, 13) to (start + 0, 19)
-- Code(Expression(48, Sub)) at (prev + 2, 13) to (start + 0, 23)
+- Code(Expression(43, Sub)) at (prev + 2, 13) to (start + 0, 23)
     = (c26 - c27)
-- Code(Expression(48, Sub)) at (prev + 1, 20) to (start + 0, 27)
+- Code(Expression(43, Sub)) at (prev + 1, 20) to (start + 0, 27)
     = (c26 - c27)
 - Code(Zero) at (prev + 1, 21) to (start + 0, 27)
 - Code(Expression(36, Sub)) at (prev + 2, 21) to (start + 0, 27)
     = ((c26 - c27) - Zero)
-- Code(Expression(47, Sub)) at (prev + 4, 13) to (start + 0, 19)
+- Code(Expression(42, Sub)) at (prev + 4, 13) to (start + 0, 19)
     = ((c26 - c27) - c30)
-- Code(Counter(31)) at (prev + 3, 9) to (start + 0, 25)
-- Code(Expression(45, Sub)) at (prev + 2, 5) to (start + 0, 15)
+- Code(Expression(40, Sub)) at (prev + 5, 5) to (start + 4, 6)
     = ((c29 + ((c26 - c27) - c30)) - c31)
-- Code(Expression(44, Sub)) at (prev + 3, 9) to (start + 0, 34)
-    = (((c29 + ((c26 - c27) - c30)) - c31) - Zero)
-- Code(Zero) at (prev + 2, 5) to (start + 0, 15)
-- Code(Zero) at (prev + 3, 9) to (start + 0, 44)
-- Code(Zero) at (prev + 2, 1) to (start + 0, 2)
-Highest counter ID seen: c31
+- Code(Zero) at (prev + 5, 5) to (start + 4, 6)
+- Code(Zero) at (prev + 5, 1) to (start + 0, 2)
+Highest counter ID seen: c29
 

tests/crashes/105249.rs

@@ -2,7 +2,7 @@
 //@ compile-flags: -Zpolymorphize=on
 
 trait Foo<T> {
-    fn print<'a>(&'a self) where T: 'a { println!("foo"); }
+    fn print<'a>(&'a self) where T: 'a { println!("{}", "foo"); }
 }
 
 impl<'a> Foo<&'a ()> for () { }

tests/incremental/hashes/inherent_impls.rs

@@ -83,7 +83,7 @@ impl Foo {
     //--------------------------
     #[inline]
     pub fn method_body_inlined() {
-        // -----------------------
+        // ---------------------
     }
 }
 
@@ -105,7 +105,7 @@ impl Foo {
     #[rustc_clean(cfg="cfail6")]
     #[inline]
     pub fn method_body_inlined() {
-        println!("Hello, world!");
+        println!("{}", "Hello");
     }
 }
 

tests/incremental/hygiene/auxiliary/cached_hygiene.rs

@@ -9,7 +9,7 @@
 #[allow(unused)]
 macro_rules! first_macro {
     () => {
-        println!("New call!");
+        println!("{}", "hola");
     }
 }
 

tests/ui/borrowck/issue-64453.rs

@@ -3,7 +3,6 @@ struct Value;
 
 static settings_dir: String = format!("");
 //~^ ERROR cannot call non-const fn
-//~| ERROR is not yet stable as a const
 
 fn from_string(_: String) -> Value {
     Value

tests/ui/borrowck/issue-64453.stderr

@@ -1,12 +1,3 @@
-error: `Arguments::<'a>::new_const` is not yet stable as a const fn
-  --> $DIR/issue-64453.rs:4:31
-   |
-LL | static settings_dir: String = format!("");
-   |                               ^^^^^^^^^^^
-   |
-   = help: add `#![feature(const_fmt_arguments_new)]` to the crate attributes to enable
-   = note: this error originates in the macro `$crate::__export::format_args` which comes from the expansion of the macro `format` (in Nightly builds, run with -Z macro-backtrace for more info)
-
 error[E0015]: cannot call non-const fn `format` in statics
   --> $DIR/issue-64453.rs:4:31
    |
@@ -18,7 +9,7 @@ LL | static settings_dir: String = format!("");
    = note: this error originates in the macro `format` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0507]: cannot move out of static item `settings_dir`
-  --> $DIR/issue-64453.rs:14:37
+  --> $DIR/issue-64453.rs:13:37
    |
 LL |     let settings_data = from_string(settings_dir);
    |                                     ^^^^^^^^^^^^ move occurs because `settings_dir` has type `String`, which does not implement the `Copy` trait
@@ -28,7 +19,7 @@ help: consider cloning the value if the performance cost is acceptable
 LL |     let settings_data = from_string(settings_dir.clone());
    |                                                 ++++++++
 
-error: aborting due to 3 previous errors
+error: aborting due to 2 previous errors
 
 Some errors have detailed explanations: E0015, E0507.
 For more information about an error, try `rustc --explain E0015`.

tests/ui/consts/const-format-arguments.rs

@@ -1,5 +1,5 @@
-
 pub fn main() {
     const A: std::fmt::Arguments = std::fmt::Arguments::new_const(&[&"hola"]);
     //~^ use of unstable library feature
+    //~| temporary value dropped while borrowed
 }

tests/ui/consts/const-format-arguments.stderr

@@ -1,20 +1,23 @@
 error[E0658]: use of unstable library feature 'fmt_internals'
-  --> $DIR/const-format-arguments.rs:3:36
+  --> $DIR/const-format-arguments.rs:2:36
    |
 LL |     const A: std::fmt::Arguments = std::fmt::Arguments::new_const(&[&"hola"]);
    |                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: add `#![feature(fmt_internals)]` to the crate attributes to enable
    = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
 
-error: `Arguments::<'a>::new_const` is not yet stable as a const fn
-  --> $DIR/const-format-arguments.rs:3:36
+error[E0716]: temporary value dropped while borrowed
+  --> $DIR/const-format-arguments.rs:2:68
    |
 LL |     const A: std::fmt::Arguments = std::fmt::Arguments::new_const(&[&"hola"]);
-   |                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: add `#![feature(const_fmt_arguments_new)]` to the crate attributes to enable
+   |                                    --------------------------------^^^^^^^^^-
+   |                                    |                               |        |
+   |                                    |                               |        temporary value is freed at the end of this statement
+   |                                    |                               creates a temporary value which is freed while still in use
+   |                                    using this value as a constant requires that borrow lasts for `'static`
 
 error: aborting due to 2 previous errors
 
-For more information about this error, try `rustc --explain E0658`.
+Some errors have detailed explanations: E0658, E0716.
+For more information about an error, try `rustc --explain E0658`.

tests/ui/rfcs/rfc-2632-const-trait-impl/issue-79450.rs

@@ -1,6 +1,5 @@
 //@ compile-flags: -Znext-solver
 #![allow(incomplete_features)]
-#![feature(const_fmt_arguments_new)]
 #![feature(const_trait_impl, effects)]
 
 #[const_trait]

tests/ui/rfcs/rfc-2632-const-trait-impl/issue-79450.stderr

@@ -1,5 +1,5 @@
 error[E0015]: cannot call non-const fn `_print` in constant functions
-  --> $DIR/issue-79450.rs:11:9
+  --> $DIR/issue-79450.rs:10:9
    |
 LL |         println!("lul");
    |         ^^^^^^^^^^^^^^^