Hello,
I pushed a commit (c85eface68940368f696807e97ac7d707e8a73eb) that treats
undefined macro invocations as undefined. Previously, if "WUMBO" were
undefined, a macro invocation such as "WUMBO(O_RDONLY)" would evaluate to
"0(0)" and the compiler would report this as a syntax error. Now, any undefined
macro invocation (with parameters) will just evaluated to 0 and the parameters
will be ignored.
I created this changed based on a real-world need: nolibc (included with the
Linux kernel source) makes use of the __has_attribute macro, which seems to be
built-in to GCC, but was defined in such a way in nolibc where it would not be
defined everywhere it was used. This meant that compiling nolibc with
TinyCC would treat __has_attribute as 0 and its parameters as (0), as described
above.
You could argue that this is undesirable behavior. I didn't know I could just
push right to the mob branch, so I was expecting a little more debate and
review before submitting.
The patch is attached.
Cheers,
- Jonathan M. Wilbur
diff --git a/tccpp.c b/tccpp.c
index 6f2bc173..a59ba814 100644
--- a/tccpp.c
+++ b/tccpp.c
@@ -1506,6 +1506,20 @@ static int expr_preprocess(TCCState *s1)
tokc.i = c;
} else {
/* if undefined macro, replace with zero */
+ next_nomacro();
+ // If the undefined macro is followed by parens, just skip them.
+ if (tok == '(') {
+ int bracket_depth = 1;
+ while (bracket_depth > 0) {
+ next();
+ if (tok == '(')
+ bracket_depth++;
+ else if (tok == ')')
+ bracket_depth--;
+ }
+ } else {
+ unget_tok(tok); // Is this actually the function I want?
+ }
tok = TOK_CINT;
tokc.i = 0;
}
diff --git a/tests/undef_func_macro.c b/tests/undef_func_macro.c
new file mode 100644
index 00000000..00db8ad0
--- /dev/null
+++ b/tests/undef_func_macro.c
@@ -0,0 +1,13 @@
+int main () {
+// This used to evaluate to 0 (0), which is invalid.
+// Now it should evaluate to 0.
+#if WUMBOED(WUMBO)
+#endif
+
+// Just trying a more complicated test case.
+#if WUMBO && defined(WUMBOLOGY) || WUMBOED(WUMBO) && !WUMBOLOGY
+ return 0;
+#elif WUMBO && defined(WUMBOLOGY) || WUMBOED(WUMBO) && !WUMBOLOGY
+ return 1;
+#endif
+}
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