[clang] [Driver][BoundsSafety] Add -fbounds-safety-experimental flag (PR #70480)

[Yeoul Na via cfe-commits]

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@@ -330,6 +330,14 @@ def warn_alias_with_section : Warning<
   "as the %select{aliasee|resolver}2">,
   InGroup<IgnoredAttributes>;
 
+let CategoryName = "Bounds Safety Issue" in {
+def err_bounds_safety_lang_not_supported : Error<
+  "bounds safety is only supported for C">;
+def warn_bounds_safety_asm_ignored : Warning<
+  "'-fbounds-safety' is ignored for assembly">,
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rapidsna wrote:

> @MaskRay It seems both `Clang` and `ClangAs` are invoked for the `clang` command with an assembly input (i.e., `ClangAs` is invoked after `Clang`) so it seems to me that most options are already `claimed` in `Clang` and so `warning: argument unused during compilation` doesn't seem to fire for `clang` in most cases including `-fsanitize=address`.

I just confirmed that this is happening when the input file format is `.s` and no `-x` is provided from the command line. If we do `-x assembler` then only `ClangAs` is launched and the unused option warning fires as expected.

https://github.com/llvm/llvm-project/pull/70480