From: Antonio Borneo <borneo.antonio@gmail.com>
Date: Sun, 19 Mar 2023 09:57:04 +0000 (+0100)
Subject: helper/compiler: fix build on MacOS
X-Git-Url: https://review.openocd.org/gitweb?p=openocd.git;a=commitdiff_plain;h=9ce6b0898e5c0b2d6b6928b93b18137fecd6a32d

helper/compiler: fix build on MacOS

On MacOS, clang defines [1]:
	#define __nonnull _Nonnull
that creates incompatibility with GCC and with the macro __nonnull
defined in some libc.

Detect clang on MacOS and undefine __nonnull.

Change-Id: I64fcf51b102ea91c196e657debd8c267943a2b08
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Links: [1] https://github.com/llvm/llvm-project/blob/llvmorg-16.0.0/clang/lib/Frontend/InitPreprocessor.cpp#L1226
Reviewed-on: https://review.openocd.org/c/openocd/+/7544
Tested-by: jenkins
---

diff --git a/src/helper/compiler.h b/src/helper/compiler.h
index 8f6c09950b..33a075d64f 100644
--- a/src/helper/compiler.h
+++ b/src/helper/compiler.h
@@ -32,7 +32,15 @@
 /*
  * The __nonnull function attribute marks pointer parameters that
  * must not be NULL.
+ *
+ * clang for Apple defines
+ * #define __nonnull _Nonnull
+ * that is a per argument attribute, incompatible with the gcc per function attribute __nonnull__.
+ * Undefine it to keep compatibility among compilers.
  */
+#if defined(__clang__) && defined(__APPLE__)
+# undef __nonnull
+#endif
 #ifndef __nonnull
 # if __has_attribute(__nonnull__)
 #  define __nonnull(params) __attribute__ ((__nonnull__ params))