compiler: avoid barfing when config.h & the current -std= mode mismatch

[ccan] / ccan / compiler / compiler.h

diff --git a/ccan/compiler/compiler.h b/ccan/compiler/compiler.h
index d57d814b3711213c978602cd46c7c6e2e67ccf7d..bce4f25a122612d7f26f8e846564747a01836b3b 100644 (file)
--- a/ccan/compiler/compiler.h
+++ b/ccan/compiler/compiler.h
@@ -1,7 +1,9 @@
+/* CC0 (Public domain) - see LICENSE file for details */
 #ifndef CCAN_COMPILER_H
 #define CCAN_COMPILER_H
 #include "config.h"
 
+#ifndef COLD
 #if HAVE_ATTRIBUTE_COLD
 /**
  * COLD - a function is unlikely to be called.
@@ -15,11 +17,33 @@
  *     fprintf(stderr, "Error: %s (%s)\n", reason, strerror(errno));
  * }
  */
-#define COLD __attribute__((cold))
+#define COLD __attribute__((__cold__))
 #else
 #define COLD
 #endif
+#endif
 
+#ifndef NORETURN
+#if HAVE_ATTRIBUTE_NORETURN
+/**
+ * NORETURN - a function does not return
+ *
+ * Used to mark a function which exits; useful for suppressing warnings.
+ *
+ * Example:
+ * static void NORETURN fail(const char *reason)
+ * {
+ *     fprintf(stderr, "Error: %s (%s)\n", reason, strerror(errno));
+ *     exit(1);
+ * }
+ */
+#define NORETURN __attribute__((__noreturn__))
+#else
+#define NORETURN
+#endif
+#endif
+
+#ifndef PRINTF_FMT
 #if HAVE_ATTRIBUTE_PRINTF
 /**
  * PRINTF_FMT - a function takes printf-style arguments
@@ -36,21 +60,39 @@
 #else
 #define PRINTF_FMT(nfmt, narg)
 #endif
+#endif
 
+#ifndef CONST_FUNCTION
 #if HAVE_ATTRIBUTE_CONST
 /**
- * IDEMPOTENT - a function's return depends only on its argument
+ * CONST_FUNCTION - a function's return depends only on its argument
  *
  * This allows the compiler to assume that the function will return the exact
  * same value for the exact same arguments.  This implies that the function
  * must not use global variables, or dereference pointer arguments.
  */
-#define IDEMPOTENT __attribute__((const))
+#define CONST_FUNCTION __attribute__((__const__))
+#else
+#define CONST_FUNCTION
+#endif
+
+#ifndef PURE_FUNCTION
+#if HAVE_ATTRIBUTE_PURE
+/**
+ * PURE_FUNCTION - a function is pure
+ *
+ * A pure function is one that has no side effects other than it's return value
+ * and uses no inputs other than it's arguments and global variables.
+ */
+#define PURE_FUNCTION __attribute__((__pure__))
 #else
-#define IDEMPOTENT
+#define PURE_FUNCTION
+#endif
+#endif
 #endif
 
 #if HAVE_ATTRIBUTE_UNUSED
+#ifndef UNNEEDED
 /**
  * UNNEEDED - a variable/function may not be needed
  *
@@ -67,8 +109,10 @@
  *     counter += add;
  * }
  */
-#define UNNEEDED __attribute__((unused))
+#define UNNEEDED __attribute__((__unused__))
+#endif
 
+#ifndef NEEDED
 #if HAVE_ATTRIBUTE_USED
 /**
  * NEEDED - a variable/function is needed
@@ -84,12 +128,14 @@
  *             printf("Counter is %i\n", counter);
  *     }
  */
-#define NEEDED __attribute__((used))
+#define NEEDED __attribute__((__used__))
 #else
 /* Before used, unused functions and vars were always emitted. */
-#define NEEDED __attribute__((unused))
+#define NEEDED __attribute__((__unused__))
+#endif
 #endif
 
+#ifndef UNUSED
 /**
  * UNUSED - a parameter is unused
  *
@@ -104,13 +150,21 @@
  *             return 0;
  *     }
  */
-#define UNUSED __attribute__((unused))
+#define UNUSED __attribute__((__unused__))
+#endif
 #else
+#ifndef UNNEEDED
 #define UNNEEDED
+#endif
+#ifndef NEEDED
 #define NEEDED
+#endif
+#ifndef UNUSED
 #define UNUSED
 #endif
+#endif
 
+#ifndef IS_COMPILE_CONSTANT
 #if HAVE_BUILTIN_CONSTANT_P
 /**
  * IS_COMPILE_CONSTANT - does the compiler know the value of this expression?
@@ -130,7 +184,7 @@
  *     const char *greek_name(enum greek greek);
  *
  *     // Inline version.
- *     static inline char *_greek_name(enum greek greek)
+ *     static inline const char *_greek_name(enum greek greek)
  *     {
  *             switch (greek) {
  *             case ALPHA: return "alpha";
@@ -152,7 +206,9 @@
 /* If we don't know, assume it's not. */
 #define IS_COMPILE_CONSTANT(expr) 0
 #endif
+#endif
 
+#ifndef WARN_UNUSED_RESULT
 #if HAVE_WARN_UNUSED_RESULT
 /**
  * WARN_UNUSED_RESULT - warn if a function return value is unused.
@@ -167,8 +223,9 @@
  *     return realloc(buf, (*size) *= 2);
  * }
  */
-#define WARN_UNUSED_RESULT __attribute__((warn_unused_result))
+#define WARN_UNUSED_RESULT __attribute__((__warn_unused_result__))
 #else
 #define WARN_UNUSED_RESULT
 #endif
+#endif
 #endif /* CCAN_COMPILER_H */