Hello,
the simplest way to make this problem visible is to instrument the functions
type_decl and post_type:
diff --git a/tccgen.c b/tccgen.c
index 87ec798..7fa6c72 100644
--- a/tccgen.c
+++ b/tccgen.c
@@ -4374,7 +4374,7 @@ static int post_type(CType *type, AttributeDef *ad, int
storage, int td)
Sym **plast, *s, *first;
AttributeDef ad1;
CType pt;
-
+ n = 0xf00f0011;
if (tok == '(') {
/* function type, or recursive declarator (return if so) */
next();
@@ -4410,6 +4410,7 @@ static int post_type(CType *type, AttributeDef *ad, int
storage, int td)
}
convert_parameter_type(&pt);
arg_size += (type_size(&pt, &align) + PTR_SIZE - 1) / PTR_SIZE;
+ if (n == 0xf00f0011) printf("using n uninitialized\n");
s = sym_push(n | SYM_FIELD, &pt, 0, 0);
*plast = s;
plast = &s->next;
@@ -4583,7 +4584,7 @@ static CType *type_decl(CType *type, AttributeDef *ad,
int *v, int td)
parse_attribute(ad);
post = type_decl(type, ad, v, td);
skip(')');
- }
+ } else printf("*v left uninitialized\n");
} else if (tok >= TOK_IDENT && (td & TYPE_DIRECT)) {
/* type identifier */
*v = tok;
The function post_type declares an automatic variable n and does not initialize
it. Setting it to 0xf00f0011 allows to see that it has not been assigned when
it is used later in this function (ored with SYM_FIELD and passed as argument
to the function sym_push). When “using n uninitialized” is printed in the
instrumented version of TCC, it means that n would have been used uninitialized
in the uninstrumented version of the compiler.
$ cat cr.i
int f ( int ( )
$ ./tcc cr.i
*v left uninitialized
using n uninitialized
cr.i:2: error: ',' expected (got "<eof>")
Some inputs cause “*v left uninitialized” to be printed but not “using n
uninitialized”:
$ cat cr.i
int f(void) { ( int ( )
$ ./tcc cr.i
*v left uninitialized
cr.i:2: error: ')' expected (got "<eof>")
I have not found any syntactically correct input that caused “*v left
uninitialized” to be printed but not “using n uninitialized”, so a solution
*might* be to make TCC error out at the point where I made it print out “*v
left uninitialized”, but this is for someone with better understanding of the
code than me to decide.
Pascal
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