From d4b1fd9cdb7ae07fa6be941ac95f97ece175fe55 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20Storsj=C3=B6?= <martin@martin.st>
Date: Tue, 31 Mar 2020 23:54:17 +0300
Subject: [PATCH] meson: Don't misdetect stpcpy on windows platforms on clang

See https://github.com/mesonbuild/meson/issues/3672 and
https://github.com/mesonbuild/meson/issues/5628 for explanations
of cases where meson misdetects functions due to clang builtins (that
always are available, regardless of whether the platform actually
provides them).

The same also happens on GCC 10, which added support for __has_builtin.

Upstream-Status: Backport [https://github.com/GNOME/glib/commit/1b94bfbd72dbbfb696fa68f3742f40998096b438]
Signed-off-by: Khem Raj <raj.khem@gmail.com>
---
 meson.build | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/meson.build b/meson.build
index 72ca194..bbdac1c 100644
--- a/meson.build
+++ b/meson.build
@@ -533,13 +533,23 @@ foreach f : functions
   endif
 endforeach
 
-# Check that stpcpy() is usable; must use header
-if cc.has_function('stpcpy', prefix : '#include <string.h>')
+# Check that stpcpy() is usable; must use header.
+# cc.has_function() in some cases (clang, gcc 10+) assumes that if the
+# compiler provides a builtin of the same name that the function exists, while
+# it's in fact not provided by any header or library. This is true for
+# stpcpy() on Windows using clang and gcc as well as posix_memalign() using
+# gcc on Windows. Skip these checks on Windows for now to avoid false
+# positives. See https://github.com/mesonbuild/meson/pull/7116,
+# https://github.com/mesonbuild/meson/issues/3672 and
+# https://github.com/mesonbuild/meson/issues/5628.
+# FIXME: Once meson no longer returns success for stpcpy() and
+# posix_memalign() on Windows using GCC and clang we can remove this.
+if host_system != 'windows' and cc.has_function('stpcpy', prefix : '#include <string.h>')
   glib_conf.set('HAVE_STPCPY', 1)
 endif
 
 # Check that posix_memalign() is usable; must use header
-if cc.has_function('posix_memalign', prefix : '#include <stdlib.h>')
+if host_system != 'windows' and cc.has_function('posix_memalign', prefix : '#include <stdlib.h>')
   glib_conf.set('HAVE_POSIX_MEMALIGN', 1)
 endif
 
-- 
2.26.2