False positive expression must have a constant value with __builtin_choose_expr in _Static_assert

[sammko]

Environment

• OS and Version: Arch
• VS Code Version: 1.74.0-insider 96db0b339360bc72d27d869d81a557540ad5f800
• C/C++ Extension Version: v1.13.4 Pre-Release

Bug Summary and Steps to Reproduce

#define ELEMENTSOF(x)                                                    \
        (__builtin_choose_expr(                                          \
                !__builtin_types_compatible_p(typeof(x), typeof(&*(x))), \
                sizeof(x)/sizeof((x)[0]),                                \
                (void)0))

int main(void) {
    int array1[1] = {0};
    _Static_assert(ELEMENTSOF(array1) <= 20, "hi");
    return 0;
}

An error "expression must have a constant value" is reported. Changing compiler, c standard and intelli sense mode didn't help. The program compiles under both gcc and clang with -Wall -Wextra -pedantic. gcc is quiet, clang gives only a warning

xyz.c:9:20: warning: extension used [-Wlanguage-extension-token]
    _Static_assert(ELEMENTSOF(array1) <= 20, "hi");
                   ^
xyz.c:3:47: note: expanded from macro 'ELEMENTSOF'
                !__builtin_types_compatible_p(typeof(x), typeof(&*(x))), \
                                              ^
xyz.c:9:20: warning: extension used [-Wlanguage-extension-token]
xyz.c:3:58: note: expanded from macro 'ELEMENTSOF'
                !__builtin_types_compatible_p(typeof(x), typeof(&*(x))), \

Related to #8294

[sean-mcmanus]

This is a duplicate of #9368

[sammko]

Is it? Happens with

"compilerPath": "/usr/bin/gcc",
"intelliSenseMode": "linux-gcc-x64",

Also no function pointers involved?

[sean-mcmanus]

The fix should be available when we release 1.14.0 (pre-release) -- not sure when yet. The issue I thought this was a duplicate of was already fixed in 1.13.4.

[sammko]

Awesome, thanks 👍

[sean-mcmanus]

The fix is available with 1.14.0 (pre-release): https://github.com/microsoft/vscode-cpptools/releases/tag/v1.14.0