If we have new features introduced by C11, use them

Instead of using hacks or compiler-specific features, if we have
standard features as defined in ISO C11, use them.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

aclocal.m4

@@ -73,3 +73,27 @@ void *foo(void)
     [Define to 1 if your compiler supports __attribute__(($1)) on functions])],
  [AC_MSG_RESULT([no])])
 ])
+
+dnl --------------------------------------------------------------------------
+dnl PA_FUNC_ATTRIBUTE_ERROR
+dnl
+dnl See if this compiler supports __attribute__((error("foo")))
+dnl The generic version of this doesn't work as it makes the compiler
+dnl throw an error by design.
+dnl --------------------------------------------------------------------------
+AC_DEFUN(PA_FUNC_ATTRIBUTE_ERROR,
+[AC_MSG_CHECKING([if $CC supports the error function attribute])
+ AC_COMPILE_IFELSE([AC_LANG_SOURCE([
+#include <stdarg.h>
+extern void __attribute__((error("message"))) barf(void);
+void foo(void)
+{
+	if (0)
+		barf();
+}
+ ])],
+ [AC_MSG_RESULT([yes])
+  AC_DEFINE(m4_toupper([HAVE_FUNC_ATTRIBUTE_ERROR]), 1,
+    [Define to 1 if your compiler supports __attribute__((error)) on functions])],
+ [AC_MSG_RESULT([no])])
+])

asm/parser.c

@@ -492,7 +492,7 @@ restart_parse:
     if (i == TOKEN_EOS)
         goto fail;
 
-    nasm_build_assert(P_none != 0);
+    nasm_build_assert(P_none == 0);
     memset(result->prefixes, P_none, sizeof(result->prefixes));
     result->times = 1L;
 

configure.ac

@@ -32,8 +32,6 @@ AH_TEMPLATE(WORDS_LITTLEENDIAN,
 [Define to 1 if your processor stores words with the least significant
 byte first (like Intel and VAX, unlike Motorola and SPARC).])
 
-PA_ADD_CFLAGS([-std=c99])
-
 dnl Force gcc and gcc-compatible compilers treat signed integers
 dnl as 2's complement
 PA_ADD_CFLAGS([-fwrapv])
@@ -73,6 +71,7 @@ AC_HEADER_STDC
 AC_CHECK_HEADERS(inttypes.h)
 AC_CHECK_HEADERS(strings.h)
 AC_HEADER_STDBOOL
+AC_CHECK_HEADERS(stdnoreturn.h)
 AC_CHECK_HEADERS(io.h)
 AC_CHECK_HEADERS(fcntl.h)
 AC_CHECK_HEADERS(unistd.h)
@@ -145,6 +144,7 @@ PA_FUNC_ATTRIBUTE(alloc_size, (1))
 PA_FUNC_ATTRIBUTE(format, [(printf,1,2)], int, [const char *, ...], ["%d",1])
 PA_FUNC_ATTRIBUTE(const)
 PA_FUNC_ATTRIBUTE(pure)
+PA_FUNC_ATTRIBUTE_ERROR
 
 dnl
 dnl support cchace

include/compiler.h

@@ -77,6 +77,7 @@
 # include "nasmint.h"
 #endif
 
+#include <assert.h>
 #include <stddef.h>
 #include <stdarg.h>
 #include <stdio.h>
@@ -208,7 +209,10 @@ char *strsep(char **, const char *);
 /*
  * How to tell the compiler that a function doesn't return
  */
-#ifdef HAVE_FUNC_ATTRIBUTE_NORETURN
+#ifdef HAVE_STDNORETURN_H
+# include <stdnoreturn.h>
+# define no_return noreturn void
+#elif defined(HAVE_FUNC_ATTRIBUTE_NORETURN)
 # define no_return void __attribute__((noreturn))
 #else
 # define no_return void

include/nasmlib.h

@@ -175,7 +175,18 @@ no_return nasm_assert_failed(const char *, int, const char *);
 /*
  * NASM failure at build time if x != 0
  */
-#define nasm_build_assert(x) (void)(sizeof(char[1-2*!!(x)]))
+#ifdef static_assert
+# define nasm_build_assert(x) static_assert(x, "assertion " #x " failed")
+#elif defined(HAVE_FUNC_ATTRIBUTE_ERROR)
+# define nasm_build_assert(x)                                           \
+    if (!(x)) {                                                         \
+        extern void __attribute__((error("assertion " #x " failed")))      \
+            fail(void);                                                 \
+        fail();                                                         \
+    }
+#else
+# define nasm_build_assert(x) (void)(sizeof(char[1-2*!(x)]))
+#endif
 
 /*
  * ANSI doesn't guarantee the presence of `stricmp' or