From f7226acce9761a3b82cd80099b0d09f201715274 Mon Sep 17 00:00:00 2001
From: Amjad Alsharafi <26300843+Amjad50@users.noreply.github.com>
Date: Sun, 11 Feb 2024 18:03:42 +0800
Subject: [PATCH 1/3] Remove unneeded `extern core` in `tgamma`

---
 src/math/tgamma.rs | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/math/tgamma.rs b/src/math/tgamma.rs
index e64eff61f..3f38c0b1d 100644
--- a/src/math/tgamma.rs
+++ b/src/math/tgamma.rs
@@ -22,7 +22,6 @@ Gamma(x)*Gamma(-x) = -pi/(x sin(pi x))
 
 most ideas and constants are from boost and python
 */
-extern crate core;
 use super::{exp, floor, k_cos, k_sin, pow};
 
 const PI: f64 = 3.141592653589793238462643383279502884;

From 28d0f1213914f340dda2617e526a8befb7bdd1e1 Mon Sep 17 00:00:00 2001
From: Amjad Alsharafi <26300843+Amjad50@users.noreply.github.com>
Date: Sun, 18 Feb 2024 21:23:20 +0800
Subject: [PATCH 2/3] Fix compilation errors from 5e0eca75f

The commit 5e0eca75fb14a93ec84cb3c36a90fa7d366b245e removed the
`checked` feature and replaced it by using `debug_assertions`.

There were some places that were not modified, this commit fixes them
---
 build.rs                   | 2 +-
 src/math/rem_pio2_large.rs | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/build.rs b/build.rs
index 80145a9cc..af4793e90 100644
--- a/build.rs
+++ b/build.rs
@@ -6,7 +6,7 @@ fn main() {
     #[cfg(feature = "musl-reference-tests")]
     musl_reference_tests::generate();
 
-    if !cfg!(feature = "checked") {
+    if !cfg!(debug_assertions) {
         let lvl = env::var("OPT_LEVEL").unwrap();
         if lvl != "0" {
             println!("cargo:rustc-cfg=assert_no_panic");
diff --git a/src/math/rem_pio2_large.rs b/src/math/rem_pio2_large.rs
index db97a39d4..9de3a0002 100644
--- a/src/math/rem_pio2_large.rs
+++ b/src/math/rem_pio2_large.rs
@@ -227,7 +227,7 @@ pub(crate) fn rem_pio2_large(x: &[f64], y: &mut [f64], e0: i32, prec: usize) ->
     let x1p24 = f64::from_bits(0x4170000000000000); // 0x1p24 === 2 ^ 24
     let x1p_24 = f64::from_bits(0x3e70000000000000); // 0x1p_24 === 2 ^ (-24)
 
-    #[cfg(all(target_pointer_width = "64", feature = "checked"))]
+    #[cfg(all(target_pointer_width = "64", debug_assertions))]
     assert!(e0 <= 16360);
 
     let nx = x.len();

From 9ded10304060e82d5cb71fcf8ae99a9538802c65 Mon Sep 17 00:00:00 2001
From: Amjad Alsharafi <26300843+Amjad50@users.noreply.github.com>
Date: Sun, 18 Feb 2024 21:24:30 +0800
Subject: [PATCH 3/3] Add `rustc-dep-of-std` feature to allow compiling for
 `std`

Since `std` dependencies cannot use `core` manually, it has to include
it manually as a dependencies from the package
`rustc-std-workspace-core`.

This allow us to use `libm` to compile a dependency of `std`.

This fixes the issue https://github.com/rust-lang/compiler-builtins/issues/576
---
 Cargo.toml | 11 +++++++++++
 build.rs   |  5 +++++
 2 files changed, 16 insertions(+)

diff --git a/Cargo.toml b/Cargo.toml
index d33ca61cd..e93a61af3 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -12,6 +12,12 @@ version = "0.2.8"
 edition = "2018"
 exclude = ["/ci/", "/.github/workflows/"]
 
+[dependencies]
+# Internal feature, only used when building as part of libstd, not part of the
+# stable interface of this crate.
+core = { version = '1.0.0', optional = true, package = 'rustc-std-workspace-core' }
+compiler_builtins = { version = '0.1.2', optional = true }
+
 [features]
 default = []
 
@@ -23,6 +29,11 @@ unstable = []
 # musl libc.
 musl-reference-tests = ['rand']
 
+
+# Internal feature, only used when building as part of libstd, not part of the
+# stable interface of this crate.
+rustc-dep-of-std = ['core', 'compiler_builtins']
+
 [workspace]
 members = [
   "crates/compiler-builtins-smoke-test",
diff --git a/build.rs b/build.rs
index af4793e90..c7614fb44 100644
--- a/build.rs
+++ b/build.rs
@@ -12,6 +12,11 @@ fn main() {
             println!("cargo:rustc-cfg=assert_no_panic");
         }
     }
+    // add cfg flags to suppress warnings generated from compiling `std` specifically
+    if cfg!(feature = "rustc-dep-of-std") {
+        println!("cargo:rustc-check-cfg=cfg(rustfmt)");
+        println!("cargo:rustc-check-cfg=cfg(assert_no_panic)");
+    }
 }
 
 #[cfg(feature = "musl-reference-tests")]