[committed] analyzer: fix warning_event::get_desc for global state changes

[David Malcolm via Gcc-patches]

When experimenting the a new state_machine with global state I noticed
that the fallback handling in warning_event::get_desc assumes we have
per-value states, and ICEs on global states.  Fixed thusly.

Successfully bootstrapped & regrtested on x86_64-pc-linux-gnu.
Pushed to master as 1df487a5204462f1ec0b1eab39b0a463a8d6b89f.

gcc/analyzer/ChangeLog:
        * checker-path.cc (warning_event::get_desc): Handle global state
        changes.
---
 gcc/analyzer/checker-path.cc | 29 +++++++++++++++++++++--------
 1 file changed, 21 insertions(+), 8 deletions(-)

diff --git a/gcc/analyzer/checker-path.cc b/gcc/analyzer/checker-path.cc
index 2503d024a83..c28131651c6 100644
--- a/gcc/analyzer/checker-path.cc
+++ b/gcc/analyzer/checker-path.cc
@@ -872,11 +872,17 @@ warning_event::get_desc (bool can_colorize) const
        {
          if (m_sm && flag_analyzer_verbose_state_changes)
            {
-             label_text result
-               = make_label_text (can_colorize,
-                                  "%s (%qE is in state %qs)",
-                                  ev_desc.m_buffer,
-                                  m_var, m_state->get_name ());
+             label_text result;
+             if (m_var)
+               result = make_label_text (can_colorize,
+                                         "%s (%qE is in state %qs)",
+                                         ev_desc.m_buffer,
+                                         m_var, m_state->get_name ());
+             else
+               result = make_label_text (can_colorize,
+                                         "%s (in global state %qs)",
+                                         ev_desc.m_buffer,
+                                         m_state->get_name ());
              ev_desc.maybe_free ();
              return result;
            }
@@ -886,9 +892,16 @@ warning_event::get_desc (bool can_colorize) const
     }
 
   if (m_sm)
-    return make_label_text (can_colorize,
-                           "here (%qE is in state %qs)",
-                           m_var, m_state->get_name ());
+    {
+      if (m_var)
+       return make_label_text (can_colorize,
+                               "here (%qE is in state %qs)",
+                               m_var, m_state->get_name ());
+      else
+       return make_label_text (can_colorize,
+                               "here (in global state %qs)",
+                               m_state->get_name ());
+    }
   else
     return label_text::borrow ("here");
 }
-- 
2.26.2