[Frontend] Avoid running plugins during code completion parse

Second attempt. Proper line endings.

The parsing that is done for code completion is a special case that will
discard any generated diagnostics, so avoid running plugins for this
case in the first place to avoid performance penalties due to the
plugins.

A scenario for this is for example libclang with extra plugins like tidy.

Patch by Nikolai Kosjar

Differential Revision: https://reviews.llvm.org/D46050

llvm-svn: 332586

clang/lib/Frontend/FrontendAction.cpp

@@ -153,6 +153,10 @@ FrontendAction::CreateWrappedASTConsumer(CompilerInstance &CI,
   if (FrontendPluginRegistry::begin() == FrontendPluginRegistry::end())
     return Consumer;
 
+  // If this is a code completion run, avoid invoking the plugin consumers
+  if (CI.hasCodeCompletionConsumer())
+    return Consumer;
+
   // Collect the list of plugins that go before the main action (in Consumers)
   // or after it (in AfterConsumers)
   std::vector<std::unique_ptr<ASTConsumer>> Consumers;

clang/test/Index/complete-and-plugins.c

@@ -0,0 +1,6 @@
+// RUN: c-index-test -code-completion-at=%s:7:1 -load %llvmshlibdir/PrintFunctionNames%pluginext -add-plugin print-fns %s | FileCheck %s
+// REQUIRES: plugins, examples
+// CHECK: macro definition:{{.*}}
+// CHECK-NOT: top-level-decl: "x"
+
+void x();