Rollup merge of rust-lang#144683 - tgross35:builtins-via-std-workspace, r=bjorn3,Noratrieb

Simplify library dependencies on `compiler-builtins`

The three panic-related library crates need to have access to `core`, and `compiler-builtins` needs to be in the crate graph. Rather than specifying both dependencies, switch these crates to use `rustc-std-workspace-core` which already does this.

This means there is now a single place that the `compiler-builtins` dependency needs to get configured, for everything other than `alloc` and `std`.

The second commit removes `compiler-builtins` from `std` (more details in the message).

Author: jhpratt

Cargo.lock

@@ -12,8 +12,7 @@ bench = false
 doc = false
 
 [dependencies]
-core = { path = "../core" }
-compiler_builtins = { path = "../compiler-builtins/compiler-builtins" }
+core = { path = "../rustc-std-workspace-core", package = "rustc-std-workspace-core" }
 
 [target.'cfg(target_os = "android")'.dependencies]
 libc = { version = "0.2", default-features = false }

panic_abort/Cargo.toml

@@ -13,10 +13,9 @@ doc = false
 
 [dependencies]
 alloc = { path = "../alloc" }
-core = { path = "../core" }
-unwind = { path = "../unwind" }
-compiler_builtins = { path = "../compiler-builtins/compiler-builtins" }
 cfg-if = { version = "1.0", features = ['rustc-dep-of-std'] }
+core = { path = "../rustc-std-workspace-core", package = "rustc-std-workspace-core" }
+unwind = { path = "../unwind" }
 
 [target.'cfg(not(all(windows, target_env = "msvc")))'.dependencies]
 libc = { version = "0.2", default-features = false }

panic_unwind/Cargo.toml

@@ -11,6 +11,12 @@ on crates.io will draw a dependency edge to `libcore`, the version defined in
 this repository. That should draw all the dependency edges to ensure Cargo
 builds crates successfully!
 
+`rustc-std-workspace-core` also ensures `compiler-builtins` is in the crate
+graph. This crate is used by other crates in `library/`, other than `std` and
+`alloc`, so the `compiler-builtins` setup only needs to be configured in a
+single place. (Otherwise these crates would just need to depend on `core` and
+`compiler-builtins` separately.)
+
 Note that crates on crates.io need to depend on this crate with the name `core`
 for everything to work correctly. To do that they can use:
 

rustc-std-workspace-core/README.md

@@ -18,7 +18,6 @@ cfg-if = { version = "1.0", features = ['rustc-dep-of-std'] }
 panic_unwind = { path = "../panic_unwind", optional = true }
 panic_abort = { path = "../panic_abort" }
 core = { path = "../core", public = true }
-compiler_builtins = { path = "../compiler-builtins/compiler-builtins" }
 unwind = { path = "../unwind" }
 hashbrown = { version = "0.15", default-features = false, features = [
     'rustc-dep-of-std',

std/Cargo.toml

@@ -444,17 +444,17 @@ impl<'a> DevicePathNode<'a> {
 
 impl<'a> PartialEq for DevicePathNode<'a> {
     fn eq(&self, other: &Self) -> bool {
-        let self_len = self.length();
-        let other_len = other.length();
-
-        self_len == other_len
-            && unsafe {
-                compiler_builtins::mem::memcmp(
-                    self.protocol.as_ptr().cast(),
-                    other.protocol.as_ptr().cast(),
-                    usize::from(self_len),
-                ) == 0
-            }
+        // Compare as a single buffer rather than by field since it optimizes better.
+        //
+        // SAFETY: `Protocol` is followed by a buffer of `length - sizeof::<Protocol>()`. `Protocol`
+        // has no padding so it is sound to interpret as a slice.
+        unsafe {
+            let s1 =
+                slice::from_raw_parts(self.protocol.as_ptr().cast::<u8>(), self.length().into());
+            let s2 =
+                slice::from_raw_parts(other.protocol.as_ptr().cast::<u8>(), other.length().into());
+            s1 == s2
+        }
     }
 }
 

std/src/sys/pal/uefi/helpers.rs

@@ -14,9 +14,8 @@ bench = false
 doc = false
 
 [dependencies]
-core = { path = "../core" }
-compiler_builtins = { path = "../compiler-builtins/compiler-builtins" }
 cfg-if = "1.0"
+core = { path = "../rustc-std-workspace-core", package = "rustc-std-workspace-core" }
 
 [target.'cfg(not(all(windows, target_env = "msvc")))'.dependencies]
 libc = { version = "0.2.140", features = ['rustc-dep-of-std'], default-features = false }