[CodeCompletion] Stop recording interface hash when searching CC token

Author: rintaro

lib/Parse/ParseIfConfig.cpp

@@ -614,6 +614,7 @@ ParserResult<IfConfigDecl> Parser::parseIfConfig(
   bool hasCCToken = false;
   if (SourceMgr.hasCodeCompletionBuffer() &&
       SourceMgr.getCodeCompletionBufferID() == L->getBufferID()) {
+    llvm::SaveAndRestore<Optional<llvm::MD5>> H(CurrentTokenHash, None);
     BacktrackingScope backtrack(*this);
     auto startLoc = Tok.getLoc();
     skipSingle();
@@ -676,6 +677,7 @@ ParserResult<IfConfigDecl> Parser::parseIfConfig(
 
     // Treat the region containing code completion token as "active".
     if (hasCCToken && !foundActive) {
+      llvm::SaveAndRestore<Optional<llvm::MD5>> H(CurrentTokenHash, None);
       BacktrackingScope backtrack(*this);
       auto startLoc = Tok.getLoc();
       skipUntilConditionalBlockClose();

test/SourceKit/CodeComplete/complete_sequence_in_ifconfig.swift

@@ -0,0 +1,54 @@
+struct MyStruct {
+    init() {}
+    var value: Int = 1
+}
+
+func foo(arg: MyStruct) {
+  #if true
+  _ = arg./*8:11*/
+  #else
+  _ = arg./*10:11*/
+  #endif
+}
+
+struct TestStruct {
+  #if true
+  func testActive(arg: MyStruct) {
+    _ = arg./*17:13*/
+  }
+  #else
+  func testInactive(arg: MyStruct) {
+    _ = arg./*21:13*/
+  }
+  #endif
+}
+
+// Test that (1) fast completion happens even in inactive #if blocks, and
+// (2) #if in toplevel decls invalidate cached ASTContext
+
+// RUN: %sourcekitd-test \
+// RUN:   -req=complete -pos=8:11 %s -- %s -parse-as-library == \
+// RUN:   -req=complete -pos=10:11 %s -- %s -parse-as-library == \
+// RUN:   -req=complete -pos=17:13 %s -- %s -parse-as-library == \
+// RUN:   -req=complete -pos=21:13 %s -- %s -parse-as-library \
+// RUN:   | %FileCheck %s --check-prefix=RESULT
+
+// RESULT-LABEL: key.results: [
+// RESULT-DAG: key.description: "value"
+// RESULT: ]
+// RESULT-NOT: key.reusingastcontext: 1
+
+// RESULT-LABEL: key.results: [
+// RESULT-DAG: key.description: "value"
+// RESULT: ]
+// RESULT: key.reusingastcontext: 1
+
+// RESULT-LABEL: key.results: [
+// RESULT-DAG: key.description: "value"
+// RESULT: ]
+// RESULT: key.reusingastcontext: 1
+
+// RESULT-LABEL: key.results: [
+// RESULT-DAG: key.description: "value"
+// RESULT: ]
+// RESULT-NOT: key.reusingastcontext: 1