dmd testsuite fails on compilable/stdcheaders.c with gcc-15 due to default switch to -std=gnu23 #21311
Description
The compileable/stdcheaders.c is failing with gcc-15 on x64 linux:
# REQUIRED_ARGS='-cpp=cpp-15' ./generated/run -f compilable/stdcheaders.c
... compilable/stdcheaders.c -cpp=cpp-15 -fPIC ()
==============================
Test 'compilable/stdcheaders.c' failed. The logged output:
/root/d/dmd/generated/linux/release/64/dmd -conf= -m64 -Icompilable -cpp=cpp-15 -fPIC -od/root/d/dmd/compiler/test/test_results/compilable/c -of/root/d/dmd/compiler/test/test_results/compilable/c/stdcheaders_0.o -c compilable/stdcheaders.c
/usr/lib/gcc/x86_64-pc-linux-gnu/15/include/stddef.h(465): Error: undefined identifier `nullptr`, did you mean alias `nullptr_t`?
typedef typeof(nullptr) nullptr_t;
^
==============================
Test 'compilable/stdcheaders.c' failed: Expected rc == 0, but exited with rc == 1
>>> TARGET FAILED: compilable/stdcheaders.c
FAILED targets:
- compilable/stdcheaders.c
The specific line making it fail is
One can trigger this error with older gccs as well, by passing the right -std:
- gcc-14
# REQUIRED_ARGS='-cpp=cpp-14 -P-std=gnu23' ./generated/run -f compilable/stdcheaders.c
... compilable/stdcheaders.c -cpp=cpp-14 -P-std=gnu23 -fPIC ()
==============================
Test 'compilable/stdcheaders.c' failed. The logged output:
/root/d/dmd/generated/linux/release/64/dmd -conf= -m64 -Icompilable -cpp=cpp-14 -P-std=gnu23 -fPIC -od/root/d/dmd/compiler/test/test_results/compilable/c -of/root/d/dmd/compiler/test/test_results/compilable/c/stdcheaders_0.o -c compilable/stdcheaders.c
/usr/lib/gcc/x86_64-pc-linux-gnu/14/include/stddef.h(450): Error: undefined identifier `nullptr`, did you mean alias `nullptr_t`?
typedef typeof(nullptr) nullptr_t;
^
==============================
Test 'compilable/stdcheaders.c' failed: Expected rc == 0, but exited with rc == 1
>>> TARGET FAILED: compilable/stdcheaders.c
FAILED targets:
- compilable/stdcheaders.c
- gcc-13
# REQUIRED_ARGS='-cpp=cpp-13 -P-std=gnu2x' ./generated/run -f compilable/stdcheaders.c
... compilable/stdcheaders.c -cpp=cpp-13 -P-std=gnu2x -fPIC ()
==============================
Test 'compilable/stdcheaders.c' failed. The logged output:
/root/d/dmd/generated/linux/release/64/dmd -conf= -m64 -Icompilable -cpp=cpp-13 -P-std=gnu2x -fPIC -od/root/d/dmd/compiler/test/test_results/compilable/c -of/root/d/dmd/compiler/test/test_results/compilable/c/stdcheaders_0.o -c compilable/stdcheaders.c
/usr/lib/gcc/x86_64-pc-linux-gnu/13/include/stddef.h(450): Error: undefined identifier `nullptr`, did you mean alias `nullptr_t`?
typedef typeof(nullptr) nullptr_t;
^
==============================
Test 'compilable/stdcheaders.c' failed: Expected rc == 0, but exited with rc == 1
>>> TARGET FAILED: compilable/stdcheaders.c
FAILED targets:
- compilable/stdcheaders.c
Rather then removing that line with the c23 std would it be a better idea to always pass -std=c11 or -std=gnu11 to the preprocessor, given that this is what importC supports?