C/C++: don't suggest implementation names as spelling fixes (PR c/83236)

gcc/c-family/ChangeLog:
	PR c/83236
	* c-common.c (selftest::c_family_tests): Call
	selftest::c_spellcheck_cc_tests.
	* c-common.h (selftest::c_spellcheck_cc_tests): New decl.
	* c-spellcheck.cc: Include "selftest.h".
	(name_reserved_for_implementation_p): New function.
	(should_suggest_as_macro_p): New function.
	(find_closest_macro_cpp_cb): Move the check for NT_MACRO to
	should_suggest_as_macro_p and call it.
	(selftest::test_name_reserved_for_implementation_p): New function.
	(selftest::c_spellcheck_cc_tests): New function.
	* c-spellcheck.h (name_reserved_for_implementation_p): New decl.

gcc/c/ChangeLog:
	PR c/83236
	* c-decl.c (lookup_name_fuzzy): Don't suggest names that are
	reserved for use by the implementation.

gcc/cp/ChangeLog:
	PR c/83236
	* name-lookup.c (consider_binding_level): Don't suggest names that
	are reserved for use by the implementation.

gcc/testsuite/ChangeLog:
	PR c/83236
	* c-c++-common/spellcheck-reserved.c: New test case.

From-SVN: r255453

5 files changed, 84 insertions, 1 deletions

diff --git a/gcc/c-family/ChangeLog b/gcc/c-family/ChangeLog
index ee590ed..a845fbf 100644
--- a/gcc/c-family/ChangeLog
+++ b/gcc/c-family/ChangeLog
@@ -1,5 +1,20 @@
 2017-12-06  David Malcolm  <dmalcolm@redhat.com>
 
+	PR c/83236
+	* c-common.c (selftest::c_family_tests): Call
+	selftest::c_spellcheck_cc_tests.
+	* c-common.h (selftest::c_spellcheck_cc_tests): New decl.
+	* c-spellcheck.cc: Include "selftest.h".
+	(name_reserved_for_implementation_p): New function.
+	(should_suggest_as_macro_p): New function.
+	(find_closest_macro_cpp_cb): Move the check for NT_MACRO to
+	should_suggest_as_macro_p and call it.
+	(selftest::test_name_reserved_for_implementation_p): New function.
+	(selftest::c_spellcheck_cc_tests): New function.
+	* c-spellcheck.h (name_reserved_for_implementation_p): New decl.
+
+2017-12-06  David Malcolm  <dmalcolm@redhat.com>
+
 	* c-spellcheck.cc: New file, taken from macro-handling code in
 	spellcheck-tree.c.
 	* c-spellcheck.h: New file, taken from macro-handling code in
diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c
index 1d79aee..6a343a3 100644
--- a/gcc/c-family/c-common.c
+++ b/gcc/c-family/c-common.c
@@ -8177,6 +8177,7 @@ void
 c_family_tests (void)
 {
   c_format_c_tests ();
+  c_spellcheck_cc_tests ();
 }
 
 } // namespace selftest
diff --git a/gcc/c-family/c-common.h b/gcc/c-family/c-common.h
index 27b1de9..d9bf8d0 100644
--- a/gcc/c-family/c-common.h
+++ b/gcc/c-family/c-common.h
@@ -1450,6 +1450,7 @@ namespace selftest {
   /* Declarations for specific families of tests within c-family,
      by source file, in alphabetical order.  */
   extern void c_format_c_tests (void);
+  extern void c_spellcheck_cc_tests (void);
 
   /* The entrypoint for running all of the above tests.  */
   extern void c_family_tests (void);
diff --git a/gcc/c-family/c-spellcheck.cc b/gcc/c-family/c-spellcheck.cc
index db70a64..a6b9e17 100644
--- a/gcc/c-family/c-spellcheck.cc
+++ b/gcc/c-family/c-spellcheck.cc
@@ -25,6 +25,37 @@ along with GCC; see the file COPYING3.  If not see
 #include "cpplib.h"
 #include "spellcheck-tree.h"
 #include "c-family/c-spellcheck.h"
+#include "selftest.h"
+
+/* Return true iff STR begin with an underscore and either an uppercase
+   letter or another underscore, and is thus, for C and C++, reserved for
+   use by the implementation.  */
+
+bool
+name_reserved_for_implementation_p (const char *str)
+{
+  if (str[0] != '_')
+    return false;
+  return (str[1] == '_' || ISUPPER(str[1]));
+}
+
+/* Return true iff HASHNODE is a macro that should be offered as a
+   suggestion for a misspelling.  */
+
+static bool
+should_suggest_as_macro_p (cpp_hashnode *hashnode)
+{
+  if (hashnode->type != NT_MACRO)
+    return false;
+
+  /* Don't suggest names reserved for the implementation, but do suggest the builtin
+     macros such as __FILE__, __LINE__ etc.  */
+  if (name_reserved_for_implementation_p ((const char *)hashnode->ident.str)
+      && !(hashnode->flags & NODE_BUILTIN))
+    return false;
+
+  return true;
+}
 
 /* A callback for cpp_forall_identifiers, for use by best_macro_match's ctor.
    Process HASHNODE and update the best_macro_match instance pointed to be
@@ -34,7 +65,7 @@ static int
 find_closest_macro_cpp_cb (cpp_reader *, cpp_hashnode *hashnode,
 			   void *user_data)
 {
-  if (hashnode->type != NT_MACRO)
+  if (!should_suggest_as_macro_p (hashnode))
     return 1;
 
   best_macro_match *bmm = (best_macro_match *)user_data;
@@ -55,3 +86,36 @@ best_macro_match::best_macro_match (tree goal,
 {
   cpp_forall_identifiers (reader, find_closest_macro_cpp_cb, this);
 }
+
+#if CHECKING_P
+
+namespace selftest {
+
+/* Selftests.  */
+
+/* Verify that name_reserved_for_implementation_p is sane.  */
+
+static void
+test_name_reserved_for_implementation_p ()
+{
+  ASSERT_FALSE (name_reserved_for_implementation_p (""));
+  ASSERT_FALSE (name_reserved_for_implementation_p ("foo"));
+  ASSERT_FALSE (name_reserved_for_implementation_p ("_"));
+  ASSERT_FALSE (name_reserved_for_implementation_p ("_foo"));
+  ASSERT_FALSE (name_reserved_for_implementation_p ("_42"));
+  ASSERT_TRUE (name_reserved_for_implementation_p ("_Foo"));
+  ASSERT_TRUE (name_reserved_for_implementation_p ("__"));
+  ASSERT_TRUE (name_reserved_for_implementation_p ("__foo"));
+}
+
+/* Run all of the selftests within this file.  */
+
+void
+c_spellcheck_cc_tests ()
+{
+  test_name_reserved_for_implementation_p ();
+}
+
+} // namespace selftest
+
+#endif /* #if CHECKING_P */
diff --git a/gcc/c-family/c-spellcheck.h b/gcc/c-family/c-spellcheck.h
index adc539a..838f4f2 100644
--- a/gcc/c-family/c-spellcheck.h
+++ b/gcc/c-family/c-spellcheck.h
@@ -22,6 +22,8 @@ along with GCC; see the file COPYING3.  If not see
 
 #include "spellcheck.h"
 
+extern bool name_reserved_for_implementation_p (const char *str);
+
 /* Specialization of edit_distance_traits for preprocessor macros.  */
 
 template <>