build: extend GNU C guards to clang where applicable, fix fallouts

Some GNU C version guards implicitly include the clang compiler, because
clang reports itself as GCC 4.2.1.

This implicit inclusion doesn't happen if the guard requires a GCC
version above 4.2.1.

Fix two such guards to explicitly include clang where it does support
the guarded feature:

- curl/curl.h: use `typecheck-gcc.h` with clang.
  llvm clang v14+ supports this. The corresponding Apple clang version
  is also v14.
  Ref: https://en.wikipedia.org/wiki/Xcode#Toolchain_versions
  Apple clang v14 tested OK in CI:
  https://github.com/curl/curl/actions/runs/16353901480/job/46207437204

- tool_urlglib: use `__builtin_mul_overflow()` with clang v8+.
  llvm clang v3.8+ supports this, but to accommodate for Apple clang,
  start with v8, the Apple version having the mainline v3.8 feature set.

Also fix compile warnings triggered by the above:
- lib1912: fix duplicate `;`:
  ```
  tests/libtest/lib1912.c:44:57: error: empty expression statement has no effect; remove unnecessary ';' to silence this warning [-Werror,-Wextra-semi-stmt]
   44 |       print_err(o->name, "CURLOT_LONG or CURLOT_VALUES");
      |                                                         ^
  [...]
  ```
  Ref: https://github.com/curl/curl/actions/runs/16351302841/job/46198524880?pr=17955#step:12:61

- lib2032: silence typcheck warning with a cast:
  ```
  tests/libtest/lib2032.c:145:29: error: sizeof on pointer operation will return size of 'CURL **' (aka 'void **') instead of 'CURL *[3]' (aka 'void *[3]') [-Werror,-Wsizeof-array-decay]
    145 |                   ntlm_easy + num_handles);
        |                   ~~~~~~~~~ ^
  ```
  Ref: https://github.com/curl/curl/actions/runs/16351302841/job/46198524880?pr=17955#step:12:86

Closes #17955
This commit is contained in:
Viktor Szakats 2025-07-17 19:01:42 +02:00
parent b453a447ce
commit fd2ca2399e
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4 changed files with 8 additions and 6 deletions

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@ -3317,8 +3317,9 @@ CURL_EXTERN CURLcode curl_easy_ssls_export(CURL *handle,
#include "mprintf.h"
/* the typechecker does not work in C++ (yet) */
#if defined(__GNUC__) && defined(__GNUC_MINOR__) && \
((__GNUC__ > 4) || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3)) && \
#if ((defined(__GNUC__) && defined(__GNUC_MINOR__) && \
((__GNUC__ > 4) || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3))) || \
(defined(__clang__) && __clang_major__ >= 14)) && \
!defined(__cplusplus) && !defined(CURL_DISABLE_TYPECHECK)
#include "typecheck-gcc.h"
#else