From 99d45c850e3962e4c89839dd8531de1c080b3ee7 Mon Sep 17 00:00:00 2001
From: "H. Peter Anvin" <hpa@linux.intel.com>
Date: Tue, 20 Feb 2018 12:34:17 -0800
Subject: Fix problem with C99 inlines and -Werror=missing-prototypes

Some older versions of gcc (gcc 4.2.1 at least) produce a warning,
promoted to error, on C99 inlines.  Do some work to figure out if we
need to fall back to GNU inline syntax.

Fix some issues with GNU inline syntax.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
---
 aclocal.m4         | 27 +++++++++++++++++++++++++++
 configure.ac       |  7 +++++++
 include/compiler.h | 24 +++++++++++++++---------
 include/iflag.h    |  1 -
 4 files changed, 49 insertions(+), 10 deletions(-)

diff --git a/aclocal.m4 b/aclocal.m4
index bd93193a..36d36cf8 100644
--- a/aclocal.m4
+++ b/aclocal.m4
@@ -172,3 +172,30 @@ AC_DEFUN(_PA_ADD_HEADER,
 
 AC_DEFUN(PA_ADD_HEADERS,
 [m4_map_args_w([$1],[_PA_ADD_HEADER(],[)])])
+
+dnl --------------------------------------------------------------------------
+dnl PA_CHECK_BAD_STDC_INLINE
+dnl
+dnl Some versions of gcc seem to apply -Wmissing-prototypes to C99
+dnl inline functions, which means we need to use GNU inline syntax
+dnl --------------------------------------------------------------------------
+AC_DEFUN(PA_CHECK_BAD_STDC_INLINE,
+[AC_MSG_CHECKING([if $CC supports C99 external inlines])
+ AC_COMPILE_IFELSE([AC_LANG_SOURCE([
+AC_INCLUDES_DEFAULT
+
+/* Don't mistake GNU inlines for c99 */
+#ifdef __GNUC_GNU_INLINE__
+# error "Using gnu inline standard"
+#endif
+
+inline int foo(int x)
+{
+	return x+1;
+}
+ ])],
+ [AC_MSG_RESULT([yes])
+  AC_DEFINE(HAVE_STDC_INLINE, 1,
+    [Define to 1 if your compiler supports C99 extern inline])],
+ [AC_MSG_RESULT([no])
+  PA_ADD_CFLAGS([-fgnu89-inline])])])
diff --git a/configure.ac b/configure.ac
index 1f492103..7f1e1ce6 100644
--- a/configure.ac
+++ b/configure.ac
@@ -286,6 +286,13 @@ PA_ARG_ENABLED([werror],
   PA_ADD_CFLAGS([-Werror=vla])]
 )
 
+dnl
+dnl On some versions of gcc, -Werror=missing-prototypes causes problems
+dnl with C99-style external inlines.  Test this *after* adding the -Werror
+dnl options.
+dnl
+PA_CHECK_BAD_STDC_INLINE
+
 dnl
 dnl support ccache
 dnl
diff --git a/include/compiler.h b/include/compiler.h
index 6e919d3d..95fd5ec4 100644
--- a/include/compiler.h
+++ b/include/compiler.h
@@ -214,15 +214,20 @@ size_t strnlen(const char *s, size_t maxlen);
 /*
  * Hack to support external-linkage inline functions
  */
-#ifdef __GNUC__
-# ifdef __GNUC_STDC_INLINE__
-#  define HAVE_STDC_INLINE
-# else
-#  define HAVE_GNU_INLINE
-# endif
-#elif defined(__STDC_VERSION__)
-# if __STDC_VERSION__ >= 199901L
-#  define HAVE_STDC_INLINE
+#ifndef HAVE_STDC_INLINE
+# ifdef __GNUC__
+#  ifdef __GNUC_STDC_INLINE__
+#   define HAVE_STDC_INLINE
+#  else
+#   define HAVE_GNU_INLINE
+#  endif
+# elif defined(__GNUC_GNU_INLINE__)
+/* Some other compiler implementing only GNU inline semantics? */
+#   define HAVE_GNU_INLINE
+# elif defined(__STDC_VERSION__)
+#  if __STDC_VERSION__ >= 199901L
+#   define HAVE_STDC_INLINE
+#  endif
 # endif
 #endif
 
@@ -230,6 +235,7 @@ size_t strnlen(const char *s, size_t maxlen);
 # define extern_inline inline
 #elif defined(HAVE_GNU_INLINE)
 # define extern_inline extern inline
+# define inline_prototypes
 #else
 # define inline_prototypes
 #endif
diff --git a/include/iflag.h b/include/iflag.h
index e8fa6036..5280703e 100644
--- a/include/iflag.h
+++ b/include/iflag.h
@@ -7,7 +7,6 @@
 #include <string.h>
 
 #include "iflaggen.h"
-#include "nasmlib.h"            /* For ilog2_32() */
 
 #define IF_GENBIT(bit)          (UINT32_C(1) << (bit))
 
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