libmicrohttpd2

commit e986c2bdfcc5b2d9b9af6dc8d8cf98b26bf8bf95
parent ad5c51354b622cf6494f4bd04b6952b1540dc9b7
Author: Evgeny Grin (Karlson2k) <k2k@drgrin.dev>
Date:   Sat, 29 Aug 2026 14:16:52 +0200

Improved compatibility with C++ compilers

Diffstat:
M
configure.ac
 | 
37
++++++++++++++++++++++++++++++++++++-
M
src/mhd2/mhd_align.h
 | 
8
++++++++

2 files changed, 44 insertions(+), 1 deletion(-)
diff --git a/configure.ac b/configure.ac
@@ -2105,7 +2105,42 @@ AC_CACHE_CHECK([[for C11 'alignof()' support]], [[mhd_cv_c_alignof]],
         ], [[mhd_cv_c_alignof='no']])
   ])
 AS_VAR_IF([mhd_cv_c_alignof], ["yes"],
-  [AC_DEFINE([[HAVE_C_ALIGNOF]], [1], [Define to 1 if your compiler supports 'alignof()'])])
+  [AC_DEFINE([[HAVE_C_ALIGNOF]], [1], [Define to 1 if your compiler supports 'alignof()'])]
+  ,
+  [ 
+    AC_CACHE_CHECK([[whether $CC supports __alignof__() as compile-time constant]], [[mhd_cv_cc___alignof]],
+      [
+        AC_LINK_IFELSE(
+          [
+            AC_LANG_SOURCE(
+              [[
+
+int main(void)
+{
+  int a = __alignof__(int);
+  switch(a)
+  {
+  case 0:
+    break;
+  case __alignof__(a):
+    a = 0;
+    break;
+  default:
+    break;
+  }
+  return a;
+}
+              ]]
+            )
+          ],
+          [mhd_cv_cc___alignof="yes"],[mhd_cv_cc___alignof="no"]
+        )
+      ]
+    )
+    AS_VAR_IF([mhd_cv_cc___alignof], ["yes"],
+      [AC_DEFINE([[HAVE___ALIGNOF]], [1], [Define to 1 if your compiler supports '__alignof__()'])])
+  ]
+)
 
 AC_CACHE_CHECK([whether $CC supports __attribute__((aligned ( )))],[mhd_cv_cc_attr_aligned],
   [
diff --git a/src/mhd2/mhd_align.h b/src/mhd2/mhd_align.h
@@ -85,6 +85,14 @@
 #  endif
 #endif
 
+#if !defined(mhd_ALIGNOF) && defined(__cplusplus)
+/* __alignof__ is preferred alignment, not minimal required alignment,
+   but offsetof() trick does not work in C++, so it is the best available option */
+#  ifdef HAVE___ALIGNOF
+#    define mhd_ALIGNOF(TYPE) __alignof__(TYPE)
+#  endif
+#endif /* !mhd_ALIGNOF && __cplusplus */
+
 #ifndef mhd_ALIGNOF
 #  include "sys_offsetof.h"
 #  define mhd_ALIGNOF(TYPE) \