work around ubuntu 20.10 build issue (#299)

NetHack was trying to suppress warn_unused_result in include/tradstdc.h, by defining warn_unused_result to an empty string. That began causing a build error in a system-supplied header file cdefs.h when using 20.10 ubuntu impish. Try skipping that in tradstdc.h for any linux, unless the NetHack build defines GCC_URWARN to force it into play. Co-authored-by: nhmall <[email protected]>
facebookresearch · Jan 21, 2022 · 7662821 · 7662821
1 parent fb932ff
commit 7662821
Showing 1 changed file with 2 additions and 0 deletions.
diff --git a/include/tradstdc.h b/include/tradstdc.h
@@ -429,12 +429,14 @@ typedef genericptr genericptr_t; /* (void *) or (char *) */
 #if __GNUC__ >= 3
 #define UNUSED __attribute__((unused))
 #define NORETURN __attribute__((noreturn))
+#if !defined(__linux__) || defined(GCC_URWARN)
 /* disable gcc's __attribute__((__warn_unused_result__)) since explicitly
    discarding the result by casting to (void) is not accepted as a 'use' */
 #define __warn_unused_result__ /*empty*/
 #define warn_unused_result /*empty*/
 #endif
 #endif
+#endif
 
 #ifndef PRINTF_F
 #define PRINTF_F(f, v)