rust/tests/codegen-llvm
Stuart Cook 432a4f27fe
Rollup merge of #145051 - bjorn3:prevent_linkage_symbol_name_collision, r=petrochenkov
Prevent name collisions with internal implementation details

The implementation of the linkage attribute inside extern blocks defines symbols starting with _rust_extern_with_linkage_. If someone tries to also define this symbol you will get a symbol conflict or even an ICE. By adding an unpredictable component to the symbol name, this becomes less of an issue.

Spawned from the discussion at [#t-compiler > About static variables `_rust_extern_with_linkage_*`](https://rust-lang.zulipchat.com/#narrow/channel/131828-t-compiler/topic/About.20static.20variables.20.60_rust_extern_with_linkage_*.60) cc `@ywxt`

Fixes https://github.com/rust-lang/rust/issues/144940
2025-08-08 12:52:57 +10:00
..

The files here use the LLVM FileCheck framework, documented at https://llvm.org/docs/CommandGuide/FileCheck.html.

One extension worth noting is the use of revisions as custom prefixes for FileCheck. If your codegen test has different behavior based on the chosen target or different compiler flags that you want to exercise, you can use a revisions annotation, like so:

// revisions: aaa bbb
// [bbb] compile-flags: --flags-for-bbb

After specifying those variations, you can write different expected, or explicitly unexpected output by using <prefix>-SAME: and <prefix>-NOT:, like so:

// CHECK: expected code
// aaa-SAME: emitted-only-for-aaa
// aaa-NOT:                        emitted-only-for-bbb
// bbb-NOT:  emitted-only-for-aaa
// bbb-SAME:                       emitted-only-for-bbb