build: avoid warnings: tell gcc and clang that dfaerror never returns

* src/dfa.h (__attribute__): Define.
(dfaerror): Declare with the "noreturn" attribute.
* src/dfasearch.c (dfaerror): Add an unreachable use of abort.

2 files changed, 9 insertions, 1 deletions

diff --git a/src/dfa.h b/src/dfa.h
index 79e9fd02..1c852074 100644
--- a/src/dfa.h
+++ b/src/dfa.h
@@ -39,6 +39,10 @@
 /* Number of ints required to hold a bit for every character. */
 #define CHARCLASS_INTS ((NOTCHAR + INTBITS - 1) / INTBITS)
 
+#if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 6) || __STRICT_ANSI__
+# define __attribute__(x)
+#endif
+
 /* Sets of unsigned characters are stored as bit vectors in arrays of ints. */
 typedef int charclass[CHARCLASS_INTS];
 
@@ -429,4 +433,4 @@ extern void dfastate (int, struct dfa *, int []);
 /* dfaerror() is called by the regexp routines whenever an error occurs.  It
    takes a single argument, a NUL-terminated string describing the error.
    The user must supply a dfaerror.  */
-extern void dfaerror (const char *);
+extern void dfaerror (const char *) __attribute__ ((noreturn));
diff --git a/src/dfasearch.c b/src/dfasearch.c
index 996effdb..a43f822a 100644
--- a/src/dfasearch.c
+++ b/src/dfasearch.c
@@ -49,6 +49,10 @@ void
 dfaerror (char const *mesg)
 {
   error (EXIT_TROUBLE, 0, "%s", mesg);
+
+  /* notreached */
+  /* Tell static analyzers that this function does not return.  */
+  abort ();
 }
 
 /* Number of compiled fixed strings known to exactly match the regexp.