[CodeCompletion] Skip typechecking preceding top level decls

Author: rintaro

lib/IDE/ExprContextAnalysis.cpp

@@ -104,22 +104,7 @@ void swift::ide::typeCheckContextUntil(DeclContext *DC, SourceLoc Loc) {
     DC = DC->getParent();
 
   if (auto *TLCD = dyn_cast<TopLevelCodeDecl>(DC)) {
-    // Typecheck all 'TopLevelCodeDecl's up to the target one.
-    // In theory, this is not needed, but it fails to resolve the type of
-    // 'guard'ed variable. e.g.
-    //
-    //   guard value = something() else { fatalError() }
-    //   <complete>
-    // Here, 'value' is '<error type>' unless we explicitly typecheck the
-    // 'guard' statement.
-    SourceFile *SF = DC->getParentSourceFile();
-    for (auto *D : SF->getTopLevelDecls()) {
-      if (auto Code = dyn_cast<TopLevelCodeDecl>(D)) {
-        typeCheckTopLevelCodeDecl(Code);
-        if (Code == TLCD)
-          break;
-      }
-    }
+    typeCheckTopLevelCodeDecl(TLCD);
   } else {
     typeCheckContextImpl(DC, Loc);
   }

test/IDE/complete_skipbody.swift

@@ -1,4 +1,6 @@
-// RUN: %swift-ide-test -code-completion -source-filename %s -code-completion-token COMPLETE -debug-forbid-typecheck-prefix FORBIDDEN | %FileCheck %s
+// RUN: %swift-ide-test -code-completion -source-filename %s -code-completion-token FUNCTIONBODY -debug-forbid-typecheck-prefix FORBIDDEN | %FileCheck %s
+// RUN: %swift-ide-test -code-completion -source-filename %s -code-completion-token TOPLEVEL -debug-forbid-typecheck-prefix FORBIDDEN | %FileCheck %s
+
 struct FORBIDDEN_Struct {
   func FORBIDDEN_method() -> Int? { 1 }
 }
@@ -8,6 +10,13 @@ struct MyStruct {
   var y: Int { 1 }
 }
 
+let globalUnrelated = FORBIDDEN_Struct();
+
+guard let globalValueOpt = MyStruct() as MyStruct?? else {
+  let localUnrelated = FORBIDDEN_Struct();
+  fatalError()
+}
+
 func test(valueOptOpt: MyStruct??) {
 
   let FORBIDDEN_localVar = 1
@@ -20,15 +29,27 @@ func test(valueOptOpt: MyStruct??) {
   }
 
   guard let value = valueOpt else {
+    let FORBIDDEN_localVar2 = 1
     return
   }
 
   if (value.x == 1) {
     let unrelated2 = FORBIDDEN_Struct()
-    _ = value.#^COMPLETE^#
+    _ = value.#^FUNCTIONBODY^#
   }
 }
 
+let globalValue = globalValueOpt!
+
+let FORBIDDEN_localVar = 1
+
+switch glovalValue.x {
+case let x where x < 2:
+  if x == globalValue.#^TOPLEVEL^# {}
+default:
+  break
+}
+
 // CHECK: Begin completions, 3 items
 // CHECK-DAG: Keyword[self]/CurrNominal:          self[#MyStruct#]; name=self
 // CHECK-DAG: Decl[InstanceVar]/CurrNominal:      x[#Int#]; name=x