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[libc] Fix detection of cfloat128 (#185486)

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Building compiler-rt with aarch64-buildroot-linux-gnu-gcc 15.2 causes a
build error:
```
compiler-rt-22.1.0/cmake/Modules/../../libc/src/__support/CPP/type_traits/is_complex.h:44:31:
 error: 'cfloat128' was not declared in this scope; did you mean 'float128'? [-Wtemplate-body]
```
According to
https://gcc.gnu.org/onlinedocs/gcc-15.2.0/gcc/Floating-Types.html
__float128 is not available on aarch64.

Analyzing the gcc defines for aarch64 seems to prove it:
```
$ aarch64-buildroot-linux-gnu-gcc -v
Target: aarch64-buildroot-linux-gnu
gcc version 15.2.0 (Buildroot 2026.02-114-gdadec9da56)

$ echo | aarch64-buildroot-linux-gnu-gcc -dM -E - | grep __GCC_IEC_559_COMPLEX
  #define __GCC_IEC_559_COMPLEX 2

$ echo | aarch64-buildroot-linux-gnu-gcc -dM -E - | grep __STDC_IEC_60559_COMPLEX__
  #define __STDC_IEC_60559_COMPLEX__ 201404L

$ echo | aarch64-buildroot-linux-gnu-gcc -dM -E - | grep -i float128
$
```
In contrast gcc for x86_64:
```
$ x86_64-buildroot-linux-gnu-gcc -v
Target: x86_64-buildroot-linux-gnu
gcc version 15.2.0 (Buildroot 2026.02-112-gd12ac02486)

$ echo | x86_64-buildroot-linux-gnu-gcc -dM -E - | grep __GCC_IEC_559_COMPLEX
  #define __GCC_IEC_559_COMPLEX 2

$ echo | x86_64-buildroot-linux-gnu-gcc -dM -E - | grep __STDC_IEC_60559_COMPLEX__
  #define __STDC_IEC_60559_COMPLEX__ 201404L

$ echo | x86_64-buildroot-linux-gnu-gcc -dM -E - | grep -i float128
  #define __SIZEOF_FLOAT128__ 16
```
This patch changes the or-condition to an and-condition for
    \_\_STDC_IEC_60559_COMPLEX\_\_ and \_\_SIZEOF_FLOAT128\_\_.

Signed-off-by: Bernd Kuhls <bernd@kuhls.net>
This commit is contained in:
bkuhls 2026-03-11 15:12:23 +01:00 committed by GitHub
parent 4a1105be78
commit ea9f8b7746
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1 changed files with 1 additions and 1 deletions
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2
libc/include/llvm-libc-macros/cfloat128-macros.h
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@ -27,7 +27,7 @@
#define LIBC_TYPES_HAS_CFLOAT128
#endif
#elif defined(__GNUC__)
#if (defined(__STDC_IEC_60559_COMPLEX__) || defined(__SIZEOF_FLOAT128__)) && \
#if (defined(__STDC_IEC_60559_COMPLEX__) && defined(__SIZEOF_FLOAT128__)) && \
(__GNUC__ >= 13 || (!defined(__cplusplus)))
#define LIBC_TYPES_HAS_CFLOAT128
#endif