[libc][spawn] wrong function signature for `posix_spawn`

[nickdesaulniers]

Building clang against llvm-libc fails with:

In file included from /llvm-project-main/llvm/lib/Support/Program.cpp:104:
/llvm-project-main/llvm/lib/Support/Unix/Program.inc:259:13: error: no matching function for call to 'posix_spawn'
  259 |       Err = posix_spawn(&PID, Program.str().c_str(), FileActions,
      |             ^~~~~~~~~~~
/usr/include/spawn.h:21:5: note: candidate function not viable: no known conversion from 'char **' to 'const char *__restrict *' for 5th argument
   21 | int posix_spawn(pid_t *__restrict, const char *__restrict, posix_spawn_file_actions_t *, posix_spawnattr_t *__restrict, const char *__restrict *, const char *__restrict *) __NOEXCEPT;
      |     ^                                                                                                                   ~~~~~~~~~~~~~~~~~~~~~~~~

this is because the generated spawn.h has the wrong fn signature for posix_spawn. Specifically, we generate

int posix_spawn(pid_t *__restrict, const char *__restrict, posix_spawn_file_actions_t *, posix_spawnattr_t *__restrict, const char *__restrict *, const char *__restrict *) __NOEXCEPT;

but this is subtly wrong; indeed the last two parameters are currently:

const char *__restrict *

but should be:

char * const * __restrict

This can be fixed in libc/include/spawn.yaml a la 6045146 (cc @alexprabhat99)

[llvmbot]

Hi!

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[llvmbot]

@llvm/issue-subscribers-libc

Author: Nick Desaulniers (nickdesaulniers)

Building clang against llvm-libc fails with: ``` In file included from /llvm-project-main/llvm/lib/Support/Program.cpp:104: /llvm-project-main/llvm/lib/Support/Unix/Program.inc:259:13: error: no matching function for call to 'posix_spawn' 259 | Err = posix_spawn(&PID, Program.str().c_str(), FileActions, | ^~~~~~~~~~~ /usr/include/spawn.h:21:5: note: candidate function not viable: no known conversion from 'char **' to 'const char *__restrict *' for 5th argument 21 | int posix_spawn(pid_t *__restrict, const char *__restrict, posix_spawn_file_actions_t *, posix_spawnattr_t *__restrict, const char *__restrict *, const char *__restrict *) __NOEXCEPT; | ^ ~~~~~~~~~~~~~~~~~~~~~~~~ ``` this is because the generated spawn.h has the wrong fn signature for posix_spawn. Specifically, we generate ``` int posix_spawn(pid_t *__restrict, const char *__restrict, posix_spawn_file_actions_t *, posix_spawnattr_t *__restrict, const char *__restrict *, const char *__restrict *) __NOEXCEPT; ``` but this is subtly wrong; indeed the last two parameters are currently: ```c const char *__restrict * ``` but should be: ```c char * const * __restrict ``` This can be fixed in libc/include/spawn.yaml a la https://github.com/llvm/llvm-project/commit/6045146014151a8f63a60612445de9ff6af47626 (cc @alexprabhat99)

[llvmbot]

@llvm/issue-subscribers-good-first-issue

Author: Nick Desaulniers (nickdesaulniers)

Building clang against llvm-libc fails with: ``` In file included from /llvm-project-main/llvm/lib/Support/Program.cpp:104: /llvm-project-main/llvm/lib/Support/Unix/Program.inc:259:13: error: no matching function for call to 'posix_spawn' 259 | Err = posix_spawn(&PID, Program.str().c_str(), FileActions, | ^~~~~~~~~~~ /usr/include/spawn.h:21:5: note: candidate function not viable: no known conversion from 'char **' to 'const char *__restrict *' for 5th argument 21 | int posix_spawn(pid_t *__restrict, const char *__restrict, posix_spawn_file_actions_t *, posix_spawnattr_t *__restrict, const char *__restrict *, const char *__restrict *) __NOEXCEPT; | ^ ~~~~~~~~~~~~~~~~~~~~~~~~ ``` this is because the generated spawn.h has the wrong fn signature for posix_spawn. Specifically, we generate ``` int posix_spawn(pid_t *__restrict, const char *__restrict, posix_spawn_file_actions_t *, posix_spawnattr_t *__restrict, const char *__restrict *, const char *__restrict *) __NOEXCEPT; ``` but this is subtly wrong; indeed the last two parameters are currently: ```c const char *__restrict * ``` but should be: ```c char * const * __restrict ``` This can be fixed in libc/include/spawn.yaml a la https://github.com/llvm/llvm-project/commit/6045146014151a8f63a60612445de9ff6af47626 (cc @alexprabhat99)