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Re: C++ PATCH to improve 'aka's on type printing in diagnostics
- From: Jason Merrill <jason at redhat dot com>
- To: Gabriel Dos Reis <gdr at cs dot tamu dot edu>
- Cc: gcc-patches List <gcc-patches at gcc dot gnu dot org>
- Date: Mon, 04 Jul 2011 17:28:52 -0400
- Subject: Re: C++ PATCH to improve 'aka's on type printing in diagnostics
- References: <4DF79CA1.7010001@redhat.com> <4E0DF674.7000307@redhat.com> <87mxgtes9c.fsf@gauss.cs.tamu.edu>
I thought of a different way to do it that would stay encapsulated in
type_as_string, so this is the version I'm going to check in.
Tested x86_64-pc-linux-gnu, applying to trunk.
commit 689a3e58f4eebbcdafec81f06e8af699045fff3a
Author: Jason Merrill <jason@redhat.com>
Date: Fri Jul 1 00:16:46 2011 -0400
* error.c (type_to_string): Avoid redundant akas.
diff --git a/gcc/cp/error.c b/gcc/cp/error.c
index 7c90ec4..664b918 100644
--- a/gcc/cp/error.c
+++ b/gcc/cp/error.c
@@ -2634,14 +2634,28 @@ type_to_string (tree typ, int verbose)
reinit_cxx_pp ();
dump_type (typ, flags);
+ /* If we're printing a type that involves typedefs, also print the
+ stripped version. But sometimes the stripped version looks
+ exactly the same, so we don't want it after all. To avoid printing
+ it in that case, we play ugly obstack games. */
if (typ && TYPE_P (typ) && typ != TYPE_CANONICAL (typ)
&& !uses_template_parms (typ))
{
+ int aka_start; char *p;
+ struct obstack *ob = pp_base (cxx_pp)->buffer->obstack;
+ /* Remember the end of the initial dump. */
+ int len = obstack_object_size (ob);
tree aka = strip_typedefs (typ);
pp_string (cxx_pp, " {aka");
pp_cxx_whitespace (cxx_pp);
+ /* And remember the start of the aka dump. */
+ aka_start = obstack_object_size (ob);
dump_type (aka, flags);
pp_character (cxx_pp, '}');
+ p = (char*)obstack_base (ob);
+ /* If they are identical, cut off the aka with a NUL. */
+ if (memcmp (p, p+aka_start, len) == 0)
+ p[len] = '\0';
}
return pp_formatted_text (cxx_pp);
}
diff --git a/gcc/testsuite/g++.dg/diagnostic/aka1.C b/gcc/testsuite/g++.dg/diagnostic/aka1.C
new file mode 100644
index 0000000..37f8df9
--- /dev/null
+++ b/gcc/testsuite/g++.dg/diagnostic/aka1.C
@@ -0,0 +1,15 @@
+// Basic test for typedef stripping in diagnostics.
+
+struct A {
+ void f();
+};
+
+void A::f() {
+ // We don't want an aka for the injected-class-name.
+ A a = 0; // { dg-error "type .A. requested" }
+}
+
+typedef A B;
+
+// We do want an aka for a real typedef.
+B b = 0; // { dg-error "B .aka A." }