Re: [C PATCH] -Wstringop-overflow for parameters with forward-declared sizes

2023-05-26 Thread Joseph Myers
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.

-- 
Joseph S. Myers
jos...@codesourcery.com


[C PATCH] -Wstringop-overflow for parameters with forward-declared sizes

2023-05-26 Thread Martin Uecker via Gcc-patches


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.

diff --git a/gcc/c-family/c-attribs.cc b/gcc/c-family/c-attribs.cc
index 072cfb69147..e2792ca6898 100644
--- a/gcc/c-family/c-attribs.cc
+++ b/gcc/c-family/c-attribs.cc
@@ -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)
diff --git a/gcc/testsuite/gcc.dg/pr109970.c b/gcc/testsuite/gcc.dg/pr109970.c
new file mode 100644
index 000..d234e10455f
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr109970.c
@@ -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" } */
+}
+