Add support for mutually-incompatible fix-it hints

This patch adds a method:
  rich_location::fixits_cannot_be_auto_applied
for ensuring that mutually-incompatible fix-its hints don't
lead to insane output from -fdiagnostics-generate-patch.

Fix-it hints within such rich_location instances are printed
as normal by diagnostic_show_locus, but don't affect the output
of -fdiagnostics-generate-patch.

gcc/ChangeLog:
	* diagnostic.c (diagnostic_report_diagnostic): Only add fixits
	to the edit_context if they can be auto-applied.

gcc/testsuite/ChangeLog:
	* gcc.dg/plugin/diagnostic-test-show-locus-bw.c
	(test_mutually_exclusive_suggestions): New test function.
	* gcc.dg/plugin/diagnostic-test-show-locus-generate-patch.c
	(test_mutually_exclusive_suggestions): New test function.
	* gcc.dg/plugin/diagnostic-test-show-locus-parseable-fixits.c
	(test_mutually_exclusive_suggestions): New test function.
	* gcc.dg/plugin/diagnostic_plugin_test_show_locus.c
	(test_show_locus): Add special-case for
	"test_mutually_exclusive_suggestions".

libcpp/ChangeLog:
	* include/line-map.h
	(rich_location::fixits_cannot_be_auto_applied): New method.
	(rich_location::fixits_can_be_auto_applied_p): New accessor.
	(rich_location::m_fixits_cannot_be_auto_applied): New field.
	* line-map.c (rich_location::rich_location): Initialize new field.

From-SVN: r249081

3 files changed, 32 insertions, 1 deletions

diff --git a/libcpp/ChangeLog b/libcpp/ChangeLog
index 8032d7c..13a33c3 100644
--- a/libcpp/ChangeLog
+++ b/libcpp/ChangeLog
@@ -1,3 +1,11 @@
+2017-06-09  David Malcolm  <dmalcolm@redhat.com>
+
+	* include/line-map.h
+	(rich_location::fixits_cannot_be_auto_applied): New method.
+	(rich_location::fixits_can_be_auto_applied_p): New accessor.
+	(rich_location::m_fixits_cannot_be_auto_applied): New field.
+	* line-map.c (rich_location::rich_location): Initialize new field.
+
 2017-06-05  David Malcolm  <dmalcolm@redhat.com>
 
 	* include/cpplib.h (struct cpp_callbacks): Add "comment"
diff --git a/libcpp/include/line-map.h b/libcpp/include/line-map.h
index 90d65d7..be3041d 100644
--- a/libcpp/include/line-map.h
+++ b/libcpp/include/line-map.h
@@ -1663,6 +1663,27 @@ class rich_location
   fixit_hint *get_last_fixit_hint () const;
   bool seen_impossible_fixit_p () const { return m_seen_impossible_fixit; }
 
+  /* Set this if the fix-it hints are not suitable to be
+     automatically applied.
+
+     For example, if you are suggesting more than one
+     mutually exclusive solution to a problem, then
+     it doesn't make sense to apply all of the solutions;
+     manual intervention is required.
+
+     If set, then the fix-it hints in the rich_location will
+     be printed, but will not be added to generated patches,
+     or affect the modified version of the file.  */
+  void fixits_cannot_be_auto_applied ()
+  {
+    m_fixits_cannot_be_auto_applied = true;
+  }
+
+  bool fixits_can_be_auto_applied_p () const
+  {
+    return !m_fixits_cannot_be_auto_applied;
+  }
+
 private:
   bool reject_impossible_fixit (source_location where);
   void stop_supporting_fixits ();
@@ -1686,6 +1707,7 @@ protected:
   semi_embedded_vec <fixit_hint *, MAX_STATIC_FIXIT_HINTS> m_fixit_hints;
 
   bool m_seen_impossible_fixit;
+  bool m_fixits_cannot_be_auto_applied;
 };
 
 /* A fix-it hint: a suggested insertion, replacement, or deletion of text.
diff --git a/libcpp/line-map.c b/libcpp/line-map.c
index c4b7cb2..5caaf6b 100644
--- a/libcpp/line-map.c
+++ b/libcpp/line-map.c
@@ -2012,7 +2012,8 @@ rich_location::rich_location (line_maps *set, source_location loc) :
   m_column_override (0),
   m_have_expanded_location (false),
   m_fixit_hints (),
-  m_seen_impossible_fixit (false)
+  m_seen_impossible_fixit (false),
+  m_fixits_cannot_be_auto_applied (false)
 {
   add_range (loc, true);
 }