[lldb] Make Fix-Its also apply to top-level expressions

[teemperor]

Summary

Currently top-level expressions won't automatically get Fix-Its applied. The reason
for that is that we only set the m_fixed_text member if we have a wrapping
source code (I.e. m_source_code is not zero and is wrapping some expressions).

This patch just always sets m_fixed_text to get this working.

[labath]

Sounds simple enough.

lldb/source/Plugins/ExpressionParser/Clang/ClangUserExpression.cpp

bool ClangUserExpression::Parse(DiagnosticManager &diagnostic_manager,
 
   // Check here for FixItHints.  If there are any try to apply the fixits and
   // set the fixed text in m_fixed_text before returning an error.
   if (num_errors) {
     if (diagnostic_manager.HasFixIts()) {
       if (parser.RewriteExpression(diagnostic_manager)) {
         size_t fixed_start;
         size_t fixed_end;
-        const std::string &fixed_expression =
-            diagnostic_manager.GetFixedExpression();
+        m_fixed_text = diagnostic_manager.GetFixedExpression();
         // Retrieve the original expression in case we don't have a top level
         // expression (which has no surrounding source code).
         if (m_source_code &&
-            m_source_code->GetOriginalBodyBounds(fixed_expression, m_expr_lang,
+            m_source_code->GetOriginalBodyBounds(m_fixed_text, m_expr_lang,
                                                  fixed_start, fixed_end))
           m_fixed_text =
-              fixed_expression.substr(fixed_start, fixed_end - fixed_start);
+              m_fixed_text.substr(fixed_start, fixed_end - fixed_start);
       }
     }
     return false;
   }
 
   //////////////////////////////////////////////////////////////////////////////
   // Prepare the output of the parser for execution, evaluating it statically
   // if possible

lldb/test/API/commands/expression/fixits/TestFixIts.py

def test_with_target(self):
         self.build()
         (target, process, self.thread, bkpt) = lldbutil.run_to_source_breakpoint(self,
                                         'Stop here to evaluate expressions',
                                          lldb.SBFileSpec("main.cpp"))
 
         options = lldb.SBExpressionOptions()
         options.SetAutoApplyFixIts(True)
 
+        top_level_options = lldb.SBExpressionOptions()
+        top_level_options.SetAutoApplyFixIts(True)
+        top_level_options.SetTopLevel(True)
+
         frame = self.thread.GetFrameAtIndex(0)
 
         # Try with one error:
         value = frame.EvaluateExpression("my_pointer.first", options)
         self.assertTrue(value.IsValid())
         self.assertTrue(value.GetError().Success())
         self.assertEquals(value.GetValueAsUnsigned(), 10)
 
+        # Try with one error in a top-level expression.
+        # The Fix-It changes "ptr.m" to "ptr->m".
+        expr = "struct X { int m; }; X x; X *ptr = &x; int m = ptr.m;"
+        value = frame.EvaluateExpression(expr, top_level_options)
+        # A successfully parsed top-level expression will yield an error
+        # that there is 'no value'. If a parsing error would have happened we
+        # would get a different error kind, so let's check the error kind here.
+        self.assertEquals(value.GetError().GetCString(), "error: No value")
+
         # Try with two errors:
         two_error_expression = "my_pointer.second->a"
         value = frame.EvaluateExpression(two_error_expression, options)
         self.assertTrue(value.IsValid())
         self.assertTrue(value.GetError().Success())
         self.assertEquals(value.GetValueAsUnsigned(), 20)
 
         # Now turn off the fixits, and the expression should fail: