[PATCH v2] c-family: ICE with [[gnu::nocf_check]] [PR106937]

[Marek Polacek <polacek@redhat.com>]

On Fri, Sep 30, 2022 at 09:12:24AM -0400, Jason Merrill wrote:
> On 9/29/22 18:49, Marek Polacek wrote:
> > When getting the name of an attribute, we ought to use
> > get_attribute_name, which handles both [[ ]] and __attribute__(())
> > forms.  Failure to do so may result in an ICE, like here.
> > 
> > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
> 
> How do we print the attributes with this patch?  Don't we also want to print
> the namespace, and use [[]] in the output?

Good point, however: while the testcase indeed has an attribute
in the [[]] form in the typedef, here we're printing its "aka":

warning: initialization of 'FuncPointerWithNoCfCheck' {aka 'void (__attribute__((nocf_check)) *)(void)'} from incompatible pointer type 'FuncPointer' {aka 'void (*)(void)'}

c-pretty-print.cc doesn't seem to know how to print an [[]] attribute.
I could do that, but then we'd print

  aka 'void ([[nocf_check]] *)(void)'

in the above, but that's invalid syntax!  pp_c_attributes_display appears
to be called for * and & only where you can't use an [[]] attribute.  So
perhaps we want to keep printing the GNU form here?

I noticed that pp_c_attributes has never been used, so we can just remove it.

I've also adjusted the test not to use "-w".

Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?

-- >8 --
When getting the name of an attribute, we ought to use
get_attribute_name, which handles both [[ ]] and __attribute__(())
forms.  Failure to do so may result in an ICE, like here.

pp_c_attributes has been unused since its introduction in r56273.

	PR c++/106937

gcc/c-family/ChangeLog:

	* c-pretty-print.cc (pp_c_attributes): Remove.
	(pp_c_attributes_display): Use get_attribute_name.
	* c-pretty-print.h (pp_c_attributes): Remove.

gcc/testsuite/ChangeLog:

	* gcc.dg/fcf-protection-1.c: New test.
---
 gcc/c-family/c-pretty-print.cc          | 30 +++----------------------
 gcc/c-family/c-pretty-print.h           |  1 -
 gcc/testsuite/gcc.dg/fcf-protection-1.c | 13 +++++++++++
 3 files changed, 16 insertions(+), 28 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/fcf-protection-1.c

diff --git a/gcc/c-family/c-pretty-print.cc b/gcc/c-family/c-pretty-print.cc
index efa1768f4d6..2419e149333 100644
--- a/gcc/c-family/c-pretty-print.cc
+++ b/gcc/c-family/c-pretty-print.cc
@@ -850,32 +850,8 @@ c_pretty_printer::declaration (tree t)
   pp_c_init_declarator (this, t);
 }
 
-/* Pretty-print ATTRIBUTES using GNU C extension syntax.  */
-
-void
-pp_c_attributes (c_pretty_printer *pp, tree attributes)
-{
-  if (attributes == NULL_TREE)
-    return;
-
-  pp_c_ws_string (pp, "__attribute__");
-  pp_c_left_paren (pp);
-  pp_c_left_paren (pp);
-  for (; attributes != NULL_TREE; attributes = TREE_CHAIN (attributes))
-    {
-      pp_tree_identifier (pp, TREE_PURPOSE (attributes));
-      if (TREE_VALUE (attributes))
-	pp_c_call_argument_list (pp, TREE_VALUE (attributes));
-
-      if (TREE_CHAIN (attributes))
-	pp_separate_with (pp, ',');
-    }
-  pp_c_right_paren (pp);
-  pp_c_right_paren (pp);
-}
-
 /* Pretty-print ATTRIBUTES using GNU C extension syntax for attributes
-   marked to be displayed on disgnostic.  */
+   marked to be displayed on diagnostic.  */
 
 void
 pp_c_attributes_display (c_pretty_printer *pp, tree a)
@@ -888,7 +864,7 @@ pp_c_attributes_display (c_pretty_printer *pp, tree a)
   for (; a != NULL_TREE; a = TREE_CHAIN (a))
     {
       const struct attribute_spec *as;
-      as = lookup_attribute_spec (TREE_PURPOSE (a));
+      as = lookup_attribute_spec (get_attribute_name (a));
       if (!as || as->affects_type_identity == false)
         continue;
       if (c_dialect_cxx ()
@@ -906,7 +882,7 @@ pp_c_attributes_display (c_pretty_printer *pp, tree a)
        {
          pp_separate_with (pp, ',');
        }
-      pp_tree_identifier (pp, TREE_PURPOSE (a));
+      pp_tree_identifier (pp, get_attribute_name (a));
       if (TREE_VALUE (a))
        pp_c_call_argument_list (pp, TREE_VALUE (a));
     }
diff --git a/gcc/c-family/c-pretty-print.h b/gcc/c-family/c-pretty-print.h
index be86bed4fee..92674ab4d06 100644
--- a/gcc/c-family/c-pretty-print.h
+++ b/gcc/c-family/c-pretty-print.h
@@ -119,7 +119,6 @@ void pp_c_space_for_pointer_operator (c_pretty_printer *, tree);
 /* Declarations.  */
 void pp_c_tree_decl_identifier (c_pretty_printer *, tree);
 void pp_c_function_definition (c_pretty_printer *, tree);
-void pp_c_attributes (c_pretty_printer *, tree);
 void pp_c_attributes_display (c_pretty_printer *, tree);
 void pp_c_cv_qualifiers (c_pretty_printer *pp, int qualifiers, bool func_type);
 void pp_c_type_qualifier_list (c_pretty_printer *, tree);
diff --git a/gcc/testsuite/gcc.dg/fcf-protection-1.c b/gcc/testsuite/gcc.dg/fcf-protection-1.c
new file mode 100644
index 00000000000..baad74cd86f
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/fcf-protection-1.c
@@ -0,0 +1,13 @@
+/* PR c++/106937 */
+/* { dg-options "-fcf-protection" } */
+
+[[gnu::nocf_check]] typedef void (*FuncPointerWithNoCfCheck)(void);
+typedef void (*FuncPointer)(void);
+[[gnu::nocf_check]] void testNoCfCheck();
+void testNoCfCheck(){};
+int i;
+void testNoCfCheckImpl(double i) {}
+void testNoCfCheckMismatch(FuncPointer f) {
+  FuncPointerWithNoCfCheck fNoCfCheck = f; /* { dg-warning "initialization" } */
+  (*fNoCfCheck)();
+}

base-commit: ade1e0d5896221500d1cbda38cd631cf80325aaa
-- 
2.37.3