[C] -Wstringop-overflow for parameters with forward-declared sizes
Checks
Commit Message
This is a minor change so that parameter that have
forward declarations for with -Wstringop-overflow.
Bootstrapped and regression tested on x86_64.
c: -Wstringop-overflow for parameters with forward-declared sizes
Warnings from -Wstringop-overflow do not appear for parameters declared
as VLAs when the bound refers to a parameter forward declaration. This
is fixed by splitting the loop that passes through parameters into two,
first only recording the positions of all possible size expressions
and then processing the parameters.
PR c/109970
gcc/c-family:
* c-attribs.cc (build_attr_access_from_parms): Split loop to first
record all parameters.
gcc/testsuite:
* gcc.dg/pr109970.c: New test.
Comments
On Fri, 26 May 2023, Martin Uecker via Gcc-patches wrote:
> c: -Wstringop-overflow for parameters with forward-declared sizes
>
> Warnings from -Wstringop-overflow do not appear for parameters declared
> as VLAs when the bound refers to a parameter forward declaration. This
> is fixed by splitting the loop that passes through parameters into two,
> first only recording the positions of all possible size expressions
> and then processing the parameters.
>
> PR c/109970
>
> gcc/c-family:
>
> * c-attribs.cc (build_attr_access_from_parms): Split loop to first
> record all parameters.
>
> gcc/testsuite:
>
> * gcc.dg/pr109970.c: New test.
>
OK.
@@ -5278,6 +5278,15 @@ build_attr_access_from_parms (tree parms, bool skip_voidptr)
tree argtype = TREE_TYPE (arg);
if (DECL_NAME (arg) && INTEGRAL_TYPE_P (argtype))
arg2pos.put (arg, argpos);
+ }
+
+ argpos = 0;
+ for (tree arg = parms; arg; arg = TREE_CHAIN (arg), ++argpos)
+ {
+ if (!DECL_P (arg))
+ continue;
+
+ tree argtype = TREE_TYPE (arg);
tree argspec = DECL_ATTRIBUTES (arg);
if (!argspec)
new file mode 100644
@@ -0,0 +1,15 @@
+/* PR109970
+ * { dg-do compile }
+ * { dg-options "-Wstringop-overflow" }
+ * */
+
+void bar(int x, char buf[x]);
+void foo(int x; char buf[x], int x);
+
+int main()
+{
+ char buf[10];
+ bar(11, buf); /* { dg-warning "accessing 11 bytes in a region of size 10" } */
+ foo(buf, 11); /* { dg-warning "accessing 11 bytes in a region of size 10" } */
+}
+