fix wrong result for putc variants due to operator precedence

the internal putc_unlocked macro was wrongly returning a meaningless
boolean result rather than the written character or EOF.

bug was found by reading (very surprising) asm.

diff --git a/src/internal/stdio_impl.h b/src/internal/stdio_impl.h
index ab34da2aead488849178a85705f84b5d876163a3..44497344971821c326a511ccb5687d9463730b61 100644 (file)
--- a/src/internal/stdio_impl.h
+++ b/src/internal/stdio_impl.h
@@ -105,7 +105,7 @@ hidden void __getopt_msg(const char *, const char *, const char *, size_t);
        ( ((f)->rpos != (f)->rend) ? *(f)->rpos++ : __uflow((f)) )
 
 #define putc_unlocked(c, f) \
-       ( ((unsigned char)(c)!=(f)->lbf && (f)->wpos!=(f)->wend) \
+       ( (((unsigned char)(c)!=(f)->lbf && (f)->wpos!=(f)->wend)) \
        ? *(f)->wpos++ = (c) : __overflow((f),(c)) )
 
 /* Caller-allocated FILE * operations */