[PATCH v4] c-family: ICE with [[gnu::nocf_check]] [PR106937]

[Marek Polacek <polacek@redhat.com>]

On Fri, Oct 07, 2022 at 12:17:34PM -0400, Jason Merrill wrote:
> On 10/6/22 22:12, Marek Polacek wrote:
> > On Thu, Oct 06, 2022 at 05:42:41PM -0400, Jason Merrill wrote:
> > > On 10/4/22 19:06, Marek Polacek wrote:
> > > > 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!
> > > 
> > > Indeed, it should be
> > > 
> > > void (* [[gnu::nocf_check]])(void)
> > 
> > Ok, let me fix that too, then.  I've updated the description to show
> > what we print with the patch, and what was printed before.
> 
> Oops, apparently I was wrongly assuming that the attribute appertained to
> the pointer.

So was I :/.

> Since it actually appertains to the function type, it should
> be
> 
>      void (*)(void) [[gnu::nocf_check]].
> 
> But for GCC attribute syntax, I think we want to leave the __attribute__
> where it was before, as in the manual's example
> 
>      void (__attribute__((noreturn)) ****f) (void);

Thanks, done here:

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_display wasn't able to print the [[]] form of
attributes, so this patch teaches it to.

When printing a pointer to function with a standard attribute, the attribute
should be printed after the parameter-list.  With this patch we print:

  aka 'void (*)(int) [[gnu::nocf_check]]'

pp_c_attributes has been unused since its introduction in r56273 so
this patch removes it.

	PR c++/106937

gcc/c-family/ChangeLog:

	* c-pretty-print.cc (pp_c_specifier_qualifier_list): Only print
	GNU attributes here.
	(c_pretty_printer::abstract_declarator): For a pointer to function,
	print the standard [[]] attributes here.
	(pp_c_attributes): Remove.
	(pp_c_attributes_display): Print the [[]] form if appropriate.  Use
	get_attribute_name.  Don't print a trailing space when printing the
	[[]] form.
	* c-pretty-print.h (pp_c_attributes): Remove.

gcc/cp/ChangeLog:

	* error.cc: Include "attribs.h".
	(dump_type_prefix): Only print GNU attributes here.
	(dump_type_suffix): Print standard attributes here.

gcc/testsuite/ChangeLog:

	* c-c++-common/pointer-to-fn1.c: New test.
---
 gcc/c-family/c-pretty-print.cc              | 102 +++++++++++---------
 gcc/c-family/c-pretty-print.h               |   1 -
 gcc/cp/error.cc                             |  17 +++-
 gcc/testsuite/c-c++-common/pointer-to-fn1.c |  18 ++++
 4 files changed, 92 insertions(+), 46 deletions(-)
 create mode 100644 gcc/testsuite/c-c++-common/pointer-to-fn1.c

diff --git a/gcc/c-family/c-pretty-print.cc b/gcc/c-family/c-pretty-print.cc
index efa1768f4d6..349f0a07d3e 100644
--- a/gcc/c-family/c-pretty-print.cc
+++ b/gcc/c-family/c-pretty-print.cc
@@ -466,7 +466,12 @@ pp_c_specifier_qualifier_list (c_pretty_printer *pp, tree t)
 	  {
 	    pp_c_whitespace (pp);
 	    pp_c_left_paren (pp);
-	    pp_c_attributes_display (pp, TYPE_ATTRIBUTES (pointee));
+	    /* If we're dealing with the GNU form of attributes, print this:
+		 void (__attribute__((noreturn)) *f) ();
+	       If it is the standard [[]] attribute, we'll print the attribute
+	       in c_pretty_printer::abstract_declarator.  */
+	    if (!cxx11_attribute_p (TYPE_ATTRIBUTES (pointee)))
+	      pp_c_attributes_display (pp, TYPE_ATTRIBUTES (pointee));
 	  }
 	else if (!c_dialect_cxx ())
 	  pp_c_whitespace (pp);
@@ -564,15 +569,26 @@ pp_c_parameter_type_list (c_pretty_printer *pp, tree t)
 void
 c_pretty_printer::abstract_declarator (tree t)
 {
+  bool fn_ptr_p = false;
   if (TREE_CODE (t) == POINTER_TYPE)
     {
       if (TREE_CODE (TREE_TYPE (t)) == ARRAY_TYPE
 	  || TREE_CODE (TREE_TYPE (t)) == FUNCTION_TYPE)
-	pp_c_right_paren (this);
+	{
+	  pp_c_right_paren (this);
+	  fn_ptr_p = true;
+	}
       t = TREE_TYPE (t);
     }
 
   direct_abstract_declarator (t);
+  /* If this is the standard [[]] attribute, print
+       void (*)() [[noreturn]];  */
+  if (fn_ptr_p && cxx11_attribute_p (TYPE_ATTRIBUTES (t)))
+    {
+      pp_space (this);
+      pp_c_attributes_display (this, TYPE_ATTRIBUTES (t));
+    }
 }
 
 /* direct-abstract-declarator:
@@ -850,32 +866,7 @@ 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.  */
+/* Pretty-print ATTRIBUTES marked to be displayed on diagnostic.  */
 
 void
 pp_c_attributes_display (c_pretty_printer *pp, tree a)
@@ -885,10 +876,12 @@ pp_c_attributes_display (c_pretty_printer *pp, tree a)
   if (a == NULL_TREE)
     return;
 
+  const bool std_p = cxx11_attribute_p (a);
+
   for (; a != NULL_TREE; a = TREE_CHAIN (a))
     {
-      const struct attribute_spec *as;
-      as = lookup_attribute_spec (TREE_PURPOSE (a));
+      const struct attribute_spec *as
+	= lookup_attribute_spec (get_attribute_name (a));
       if (!as || as->affects_type_identity == false)
         continue;
       if (c_dialect_cxx ()
@@ -896,26 +889,47 @@ pp_c_attributes_display (c_pretty_printer *pp, tree a)
 	/* In C++ transaction_safe is printed at the end of the declarator.  */
 	continue;
       if (is_first)
-       {
-         pp_c_ws_string (pp, "__attribute__");
-         pp_c_left_paren (pp);
-         pp_c_left_paren (pp);
-         is_first = false;
-       }
+	{
+	  if (std_p)
+	    {
+	      pp_c_left_bracket (pp);
+	      pp_c_left_bracket (pp);
+	    }
+	  else
+	    {
+	      pp_c_ws_string (pp, "__attribute__");
+	      pp_c_left_paren (pp);
+	      pp_c_left_paren (pp);
+	    }
+	  is_first = false;
+	}
       else
-       {
-         pp_separate_with (pp, ',');
-       }
-      pp_tree_identifier (pp, TREE_PURPOSE (a));
+	pp_separate_with (pp, ',');
+      tree ns;
+      if (std_p && (ns = get_attribute_namespace (a)))
+	{
+	  pp_tree_identifier (pp, ns);
+	  pp_colon (pp);
+	  pp_colon (pp);
+	}
+      pp_tree_identifier (pp, get_attribute_name (a));
       if (TREE_VALUE (a))
-       pp_c_call_argument_list (pp, TREE_VALUE (a));
+	pp_c_call_argument_list (pp, TREE_VALUE (a));
     }
 
   if (!is_first)
     {
-      pp_c_right_paren (pp);
-      pp_c_right_paren (pp);
-      pp_c_whitespace (pp);
+      if (std_p)
+	{
+	  pp_c_right_bracket (pp);
+	  pp_c_right_bracket (pp);
+	}
+      else
+	{
+	  pp_c_right_paren (pp);
+	  pp_c_right_paren (pp);
+	  pp_c_whitespace (pp);
+	}
     }
 }
 
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/cp/error.cc b/gcc/cp/error.cc
index 4514c8bbb44..8cd011fab0e 100644
--- a/gcc/cp/error.cc
+++ b/gcc/cp/error.cc
@@ -36,6 +36,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "internal-fn.h"
 #include "gcc-rich-location.h"
 #include "cp-name-hint.h"
+#include "attribs.h"
 
 #define pp_separate_with_comma(PP) pp_cxx_separate_with (PP, ',')
 #define pp_separate_with_semicolon(PP) pp_cxx_separate_with (PP, ';')
@@ -897,7 +898,12 @@ dump_type_prefix (cxx_pretty_printer *pp, tree t, int flags)
 	  {
 	    pp_cxx_whitespace (pp);
 	    pp_cxx_left_paren (pp);
-	    pp_c_attributes_display (pp, TYPE_ATTRIBUTES (sub));
+	    /* If we're dealing with the GNU form of attributes, print this:
+		 void (__attribute__((noreturn)) *f) ();
+	       If it is the standard [[]] attribute, we'll print the attribute
+	       in dump_type_suffix.  */
+	    if (!cxx11_attribute_p (TYPE_ATTRIBUTES (sub)))
+	      pp_c_attributes_display (pp, TYPE_ATTRIBUTES (sub));
 	  }
 	if (TYPE_PTR_P (t))
 	  pp_star (pp);
@@ -1027,6 +1033,15 @@ dump_type_suffix (cxx_pretty_printer *pp, tree t, int flags)
 			      TREE_CODE (t) == FUNCTION_TYPE
 			      && (flags & TFF_POINTER));
 	dump_ref_qualifier (pp, t, flags);
+	/* If this is the standard [[]] attribute, print
+	     void (*)() [[noreturn]];  */
+	if ((flags & TFF_POINTER)
+	    && cxx11_attribute_p (TYPE_ATTRIBUTES (t)))
+	  {
+	    pp_space (pp);
+	    pp_c_attributes_display (pp, TYPE_ATTRIBUTES (t));
+	    pp->padding = pp_before;
+	  }
 	if (tx_safe_fn_type_p (t))
 	  pp_cxx_ws_string (pp, "transaction_safe");
 	dump_exception_spec (pp, TYPE_RAISES_EXCEPTIONS (t), flags);
diff --git a/gcc/testsuite/c-c++-common/pointer-to-fn1.c b/gcc/testsuite/c-c++-common/pointer-to-fn1.c
new file mode 100644
index 00000000000..975885462e9
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/pointer-to-fn1.c
@@ -0,0 +1,18 @@
+/* PR c++/106937 */
+/* { dg-options "-fcf-protection" } */
+/* { dg-additional-options "-std=c++11 -fpermissive" { target c++ } } */
+/* Test printing a pointer to function with attribute.  */
+
+__attribute__((nocf_check)) typedef void (*FPA1)();
+[[gnu::nocf_check]] typedef void (*FPA2)(int);
+typedef void (*FP1)();
+typedef void (*FP2)(int);
+
+void
+g (FP1 f1, FP2 f2)
+{
+  FPA1 p1 = f1; // { dg-warning {aka 'void \(__attribute__\(\(nocf_check\)\) \*\)\(\)'} }
+  FPA2 p2 = f2; // { dg-warning {aka 'void \(\*\)\(int\) \[\[gnu::nocf_check\]\]'} }
+  FP1 p3 = p1; // { dg-warning {aka 'void \(__attribute__\(\(nocf_check\)\) \*\)\(\)'} }
+  FP2 p4 = p2; // { dg-warning {aka 'void \(\*\)\(int\) \[\[gnu::nocf_check\]\]'} }
+}

base-commit: f30e9fd33e56a5a721346ea6140722e1b193db42
-- 
2.37.3