Bug 24297 – ImportC incompatible with glibc _FORTIFY_SOURCE

$ echo '#include <stdio.h>' > test.c && dmd -P=-D_FORTIFY_SOURCE -P=-O test.c /usr/include/bits/stdio2.h(198): Error: found `0` when expecting `)` /usr/include/bits/stdio2.h(198): Error: found `)` instead of statement /usr/include/bits/stdio2.h(200): Error: found `0` when expecting `)` /usr/include/bits/stdio2.h(200): Error: found `)` instead of statement /usr/include/bits/stdio2.h(210): Error: found `0` when expecting `)` /usr/include/bits/stdio2.h(210): Error: found `)` instead of statement /usr/include/bits/stdio2.h(212): Error: found `0` when expecting `)` /usr/include/bits/stdio2.h(212): Error: found `)` instead of statement /usr/include/bits/stdio2.h(237): Error: found `0` when expecting `)` /usr/include/bits/stdio2.h(237): Error: found `)` instead of statement /usr/include/bits/stdio2.h(260): Error: no type for declarator before `return` /usr/include/bits/stdio2.h(261): Error: no type for declarator before `}` /usr/include/bits/stdio2.h(262): Error: no type for declarator before `if` /usr/include/bits/stdio2.h(264): Error: no type for declarator before `return` /usr/include/bits/stdio2.h(266): Error: no type for declarator before `}` Relevant part of the file: 194 __fortify_function __wur __fortified_attr_access (__write_only__, 1, 2) char * 195 fgets (char *__restrict __s, int __n, FILE *__restrict __stream) 196 { 197 size_t sz = __glibc_objsize (__s); 198 if (__glibc_safe_or_unknown_len (__n, sizeof (char), sz)) 199 return __fgets_alias (__s, __n, __stream); 200 if (__glibc_unsafe_len (__n, sizeof (char), sz)) 201 return __fgets_chk_warn (__s, sz, __n, __stream); 202 return __fgets_chk (__s, sz, __n, __stream); 203 } Nix enables these flags automatically for its wrapped C preprocessor. It is enabled by default but can be disabled. Not sure if this is something that's at all reasonable to implement in ImportC or not.

The usual way to handle these sorts of extensions is to make macros for them that expand to nothing, and put those macros in druntime/src/importc.h. However, this bug report has insufficient information in it to do that, though I suspect that an: #undef _FORTIFY_SOURCE might work?

> However, this bug report has insufficient information in it to do that Why do you say that? This problem should be reproducible on any GNU/Linux machine without additional setup. What information is missing? > though I suspect that an: > > #undef _FORTIFY_SOURCE > > might work? Ah, certainly, that works! Not worth fixing whatever things get expanded to?

Here is the preprocessed code: # 194 "/usr/include/bits/stdio2.h" 3 4 extern # 194 "/usr/include/bits/stdio2.h" inline # 194 "/usr/include/bits/stdio2.h" 3 4 __attribute__ ((__always_inline__)) __attribute__ ((__gnu_inline__)) __attribute__ ((__artificial__)) __attribute__ ((__warn_unused_result__)) __attribute__ ((__access__ (__write_only__, 1, 2))) char * fgets (char * __s, int __n, FILE * __stream) { size_t sz = __builtin_object_size (__s, 1 > 1); if (((__builtin_constant_p (sz) && (sz) == (long unsigned int) -1) || (((__typeof (__n)) 0 < (__typeof (__n)) -1 || (__builtin_constant_p (__n) && (__n) > 0)) && __builtin_constant_p ((((long unsigned int) (__n)) <= ((sz)) / ((sizeof (char))))) && (((long unsigned int) (__n)) <= ((sz)) / ((sizeof (char))))))) return __fgets_alias (__s, __n, __stream); if ((((__typeof (__n)) 0 < (__typeof (__n)) -1 || (__builtin_constant_p (__n) && (__n) > 0)) && __builtin_constant_p ((((long unsigned int) (__n)) <= (sz) / (sizeof (char)))) && !(((long unsigned int) (__n)) <= (sz) / (sizeof (char))))) return __fgets_chk_warn (__s, sz, __n, __stream); return __fgets_chk (__s, sz, __n, __stream); }

Reduced: #include <stdio.h> int foo() { int __n; return ((__typeof (__n)) 0 ); } Maybe just needs a #define __typeof typeof?

@WalterBright created dlang/dmd pull request #15957 "fix Issue 24297 - ImportC incompatible with glibc _FORTIFY_SOURCE" fixing this issue: - fix Issue 24297 - ImportC incompatible with glibc _FORTIFY_SOURCE https://github.com/dlang/dmd/pull/15957

dlang/dmd pull request #15957 "fix Issue 24297 - ImportC incompatible with glibc _FORTIFY_SOURCE" was merged into master: - 7ce929a02cd315abd8f0e420327625164a9c0c97 by Walter Bright: fix Issue 24297 - ImportC incompatible with glibc _FORTIFY_SOURCE https://github.com/dlang/dmd/pull/15957