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Rollup merge of #132260 - Zalathar:type-safe-cast, r=compiler-errors

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cg_llvm: Use a type-safe helper to cast `&str` and `&[u8]` to `*const c_char`

In `rustc_codegen_llvm` there are many uses of `.as_ptr().cast()` to convert a string or byte-slice to `*const c_char`, which then gets passed through FFI.

This works, but is fragile, because there's nothing constraining the pointer cast to actually be from `u8` to `c_char`. If the original value changes to something else that has an `as_ptr` method, or the context changes to expect something other than `c_char`, the cast will silently do the wrong thing.

By making the cast more explicit via a helper method, we can be sure that it will either perform the intended cast, or fail at compile time.
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Jubilee 2024-10-28 10:18:52 -07:00 • committed by GitHub
commit bd43f8e9fd
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17 changed files with 110 additions and 87 deletions
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14
compiler/rustc_codegen_llvm/src/debuginfo/mod.rs
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@ -31,7 +31,7 @@ use self::namespace::mangled_name_of_instance;
use self::utils::{DIB, create_DIArray, is_node_local_to_unit};
use crate::abi::FnAbi;
use crate::builder::Builder;
use crate::common::CodegenCx;
use crate::common::{AsCCharPtr, CodegenCx};
use crate::llvm;
use crate::llvm::debuginfo::{
DIArray, DIBuilder, DIFile, DIFlags, DILexicalBlock, DILocation, DISPFlags, DIScope, DIType,
@ -389,9 +389,9 @@ impl<'ll, 'tcx> DebugInfoCodegenMethods<'tcx> for CodegenCx<'ll, 'tcx> {
llvm::LLVMRustDIBuilderCreateMethod(
DIB(self),
containing_scope,
name.as_ptr().cast(),
name.as_c_char_ptr(),
name.len(),
linkage_name.as_ptr().cast(),
linkage_name.as_c_char_ptr(),
linkage_name.len(),
file_metadata,
loc.line,
@ -406,9 +406,9 @@ impl<'ll, 'tcx> DebugInfoCodegenMethods<'tcx> for CodegenCx<'ll, 'tcx> {
llvm::LLVMRustDIBuilderCreateFunction(
DIB(self),
containing_scope,
name.as_ptr().cast(),
name.as_c_char_ptr(),
name.len(),
linkage_name.as_ptr().cast(),
linkage_name.as_c_char_ptr(),
linkage_name.len(),
file_metadata,
loc.line,
@ -494,7 +494,7 @@ impl<'ll, 'tcx> DebugInfoCodegenMethods<'tcx> for CodegenCx<'ll, 'tcx> {
Some(llvm::LLVMRustDIBuilderCreateTemplateTypeParameter(
DIB(cx),
None,
name.as_ptr().cast(),
name.as_c_char_ptr(),
name.len(),
actual_type_metadata,
))
@ -635,7 +635,7 @@ impl<'ll, 'tcx> DebugInfoCodegenMethods<'tcx> for CodegenCx<'ll, 'tcx> {
DIB(self),
dwarf_tag,
scope_metadata,
name.as_ptr().cast(),
name.as_c_char_ptr(),
name.len(),
file_metadata,
loc.line,