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

[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 00000000000..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" } */
+}
+