C++: don't offer bogus "._0" suggestions (PR c++/86329)

PR c++/86329 reports that the C++ frontend can offer bogus suggestions like:

#include <string>

int compare()
{
  return __n1 - __n2;
}

suggested.cc: In function 'int compare()':
suggested.cc:5:10: error: '__n1' was not declared in this scope
   return __n1 - __n2;
          ^~~~
suggested.cc:5:10: note: suggested alternative: '._61'
   return __n1 - __n2;
          ^~~~
          ._61
suggested.cc:5:17: error: '__n2' was not declared in this scope
   return __n1 - __n2;
                 ^~~~
suggested.cc:5:17: note: suggested alternative: '._72'
   return __n1 - __n2;
                 ^~~~
                 ._72

The dot-prefixed names are an implementation detail of how we implement
anonymous enums found in the header files, generated via
anon_aggrname_format in make_anon_name.

This patch uses anon_aggrname_p to filter them out when considering
which names to suggest.

gcc/cp/ChangeLog:
	PR c++/86329
	* name-lookup.c (consider_binding_level): Filter out names that
	match anon_aggrname_p.

gcc/testsuite/ChangeLog:
	PR c++/86329
	* g++.dg/lookup/pr86329.C: New test.

From-SVN: r262199
This commit is contained in:
David Malcolm 2018-06-27 23:21:46 +00:00 committed by David Malcolm
parent b4324a144b
commit 5da1234bb7
4 changed files with 27 additions and 0 deletions

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@ -1,3 +1,9 @@
2018-06-27 David Malcolm <dmalcolm@redhat.com>
PR c++/86329
* name-lookup.c (consider_binding_level): Filter out names that
match anon_aggrname_p.
2018-06-27 Jason Merrill <jason@redhat.com>
* name-lookup.c (do_pushtag): If we skip a class level, also skip

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@ -5786,6 +5786,11 @@ consider_binding_level (tree name, best_match <tree, const char *> &bm,
if (!suggestion)
continue;
/* Don't suggest names that are for anonymous aggregate types, as
they are an implementation detail generated by the compiler. */
if (anon_aggrname_p (suggestion))
continue;
const char *suggestion_str = IDENTIFIER_POINTER (suggestion);
/* Ignore internal names with spaces in them. */

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@ -1,3 +1,8 @@
2018-06-27 David Malcolm <dmalcolm@redhat.com>
PR c++/86329
* g++.dg/lookup/pr86329.C: New test.
2018-06-27 Carl Love <cel@us.ibm.com>
Add test case that was supposed to be added in commit 255556 on 2017-12-11.

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@ -0,0 +1,11 @@
/* PR c++/86329: ensure we don't erroneously offer suggestions like "._0",
which are an implementation detail of how e.g. anonymous enums are
handled internally. */
enum {NONEMPTY};
int test()
{
return __0; // { dg-error "'__0' was not declared in this scope" }
// { dg-bogus "suggested alternative" "" { target *-*-* } .-1 }
}