[CodeComplete] Fix ASTUnit cached completion of macros from preamble, broken in r342528

[sammccall]

Summary

The problem is the default LoadExternal with no completer, which happens when
loading global results.

[ilya-biryukov]

LGTM

clang/lib/Sema/SemaCodeComplete.cpp

 
 void Sema::CodeCompletePreprocessorExpression() {
   ResultBuilder Results(*this, CodeCompleter->getAllocator(),
                         CodeCompleter->getCodeCompletionTUInfo(),
                         CodeCompletionContext::CCC_PreprocessorExpression);
 
   if (!CodeCompleter || CodeCompleter->includeMacros())
     AddMacroResults(PP, Results,
-                    CodeCompleter ? CodeCompleter->loadExternal() : false,
-                    true);
+                    !CodeCompleter || CodeCompleter->loadExternal(), true);
 
   // defined (<macro>)
   Results.EnterNewScope();
   CodeCompletionBuilder Builder(Results.getAllocator(),
                                 Results.getCodeCompletionTUInfo());
   Builder.AddTypedTextChunk("defined");
   Builder.AddChunk(CodeCompletionString::CK_HorizontalSpace);
   Builder.AddChunk(CodeCompletionString::CK_LeftParen);
CodeCompletionDeclConsumer Consumer(Builder,
                                         Context.getTranslationUnitDecl());
     LookupVisibleDecls(Context.getTranslationUnitDecl(), LookupAnyName,
                        Consumer,
                        !CodeCompleter || CodeCompleter->loadExternal());
   }
 
   if (!CodeCompleter || CodeCompleter->includeMacros())
     AddMacroResults(PP, Builder,
-                    CodeCompleter ? CodeCompleter->loadExternal() : false,
-                    true);
+                    !CodeCompleter || CodeCompleter->loadExternal(), true);
 
   Results.clear();
   Results.insert(Results.end(), Builder.data(),
                  Builder.data() + Builder.size());
 }

clang/test/Index/complete-macros.h

 #ifndef COMPLETE_MACROS_H_GUARD
 #define COMPLETE_MACROS_H_GUARD
 
 void in_header(int);
+#define MACRO_IN_HEADER 1
 
 #endif

clang/test/Index/complete-macros.c

 
 void test_variadic() {
   
 }
 
 // RUN: c-index-test -code-completion-at=%s:7:1 %s -I%S | FileCheck -check-prefix=CHECK-CC0 %s
 // CHECK-CC0-NOT: FOO
 // RUN: env CINDEXTEST_EDITING=1 CINDEXTEST_COMPLETION_CACHING=1 c-index-test -code-completion-at=%s:7:1 %s -I%S | FileCheck -check-prefix=CHECK-CC1 %s
+// (we had a regression that only occurred when parsing as C++, so check that too)
+// RUN: env CINDEXTEST_EDITING=1 CINDEXTEST_COMPLETION_CACHING=1 c-index-test -code-completion-at=%s:7:1 -x c++ %s -I%S | FileCheck -check-prefix=CHECK-CC1 %s
 // CHECK-CC1: macro definition:{TypedText FOO} (70)
+// CHECK-CC1: macro definition:{TypedText MACRO_IN_HEADER} (70)
 // RUN: c-index-test -code-completion-at=%s:13:13 %s -I%S | FileCheck -check-prefix=CHECK-CC2 %s
 // RUN: c-index-test -code-completion-at=%s:14:8 %s -I%S | FileCheck -check-prefix=CHECK-CC2 %s
 // RUN: env CINDEXTEST_EDITING=1 CINDEXTEST_COMPLETION_CACHING=1 c-index-test -code-completion-at=%s:14:8 %s -I%S | FileCheck -check-prefix=CHECK-CC2 %s
 // CHECK-CC2: macro definition:{TypedText nil} (32)
 // RUN: c-index-test -code-completion-at=%s:15:5 %s -I%S | FileCheck -check-prefix=CHECK-CC3 %s
 // RUN: env CINDEXTEST_EDITING=1 CINDEXTEST_COMPLETION_CACHING=1 c-index-test -code-completion-at=%s:15:5 %s -I%S | FileCheck -check-prefix=CHECK-CC3 %s
 // CHECK-CC3: macro definition:{TypedText nil} (65)
 // RUN: env CINDEXTEST_EDITING=1 CINDEXTEST_COMPLETION_CACHING=1 c-index-test -code-completion-at=%s:25:2 %s -I%S | FileCheck -check-prefix=CHECK-VARIADIC %s
 // CHECK-VARIADIC: macro definition:{TypedText variadic1}{LeftParen (}{Placeholder ...}{RightParen )} (70)
 // CHECK-VARIADIC: macro definition:{TypedText variadic2}{LeftParen (}{Placeholder args...}{RightParen )} (70)
 // CHECK-VARIADIC: macro definition:{TypedText variadic3}{LeftParen (}{Placeholder args, ...}{RightParen )} (70)
 // CHECK-VARIADIC: macro definition:{TypedText variadic4}{LeftParen (}{Placeholder first}{Comma , }{Placeholder second}{Comma , }{Placeholder args, ...}{RightParen )} (70)
 // CHECK-VARIADIC: macro definition:{TypedText variadic5}{LeftParen (}{Placeholder first}{Comma , }{Placeholder second}{Comma , }{Placeholder args...}{RightParen )} (70)
 
 // RUN: env CINDEXTEST_EDITING=1 CINDEXTEST_COMPLETION_CACHING=1 c-index-test -code-completion-at=%s:15:5 %s -I%S | FileCheck -check-prefix=CHECK-CC4 %s
 // CHECK-CC4-NOT: COMPLETE_MACROS_H_GUARD