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Unverified Commit 8cfdd370 authored by Yonggang Luo's avatar Yonggang Luo Committed by GitHub
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[clang] Fixes compile error that double colon operator cannot resolve macro...

[clang] Fixes compile error that double colon operator cannot resolve macro with parentheses. (#68618)

Error message:
```
In file included from ../src/amd/addrlib/src/core/addrobject.h:21:
../src/amd/addrlib/src/core/addrcommon.h:343:13: error: expected unqualified-id
    out = ::_tzcnt_u32(mask);
            ^
/usr/lib/llvm-15/lib/clang/15.0.6/include/bmiintrin.h:74:27: note: expanded from macro '_tzcnt_u32'
#define _tzcnt_u32(a)     (__tzcnt_u32((a)))
```

This is because both GCC/Clang doesn't support compiling the following
code:
```
#ifdef _MSC_VER
#include <intrin.h>
#else
#include <x86intrin.h>
#endif

int f(int a) {
    return ::(_tzcnt_u32)(a);
}
```

This is because the return statement expects an expression or braced
init list: http://eel.is/c++draft/stmt.jump#general-1 but we really only
need to care about the expression form (there's no braces in sight).
Grammatically, the leading :: will parse as a qualified-id because it
matches the production for nested-name-specifier:
http://eel.is/c++draft/expr.prim.id.qual#nt:qualified-id That needs to
be followed by an unqualified-id
(http://eel.is/c++draft/expr.prim.id.unqual#nt:unqualified-id), but the
open paren does not match any of the grammar productions, so this is a
syntax error.

Closes: https://github.com/llvm/llvm-project/issues/64467



Signed-off-by: default avatarYonggang Luo <luoyonggang@gmail.com>
parent 543589af
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