Merge pull request #20015 from rintaro/ide-completion-rdar45275782

[CodeCompletion] Don't try to resolve generic env for extension in inactive block

Author: rintaro

lib/Sema/TypeCheckDecl.cpp

@@ -4989,6 +4989,13 @@ void TypeChecker::validateExtension(ExtensionDecl *ext) {
   if (!isa<SourceFile>(dc))
     return;
 
+  // If this is not bound to any decls at this point, this extension is in
+  // inactive coditional compilation block. It's not safe to typecheck this
+  // extension. This happens if code completion is triggered in inactive
+  // conditional complation block.
+  if (!ext->alreadyBoundToNominal())
+    return;
+
   // Validate the nominal type declaration being extended.
   validateDecl(nominal);
 

validation-test/IDE/crashers_2_fixed/sr9001.swift

@@ -0,0 +1,20 @@
+// RUN: %target-swift-ide-test -code-completion -code-completion-token=COMPLETE_1 -source-filename=%s
+// RUN: %target-swift-ide-test -code-completion -code-completion-token=COMPLETE_2 -source-filename=%s
+
+struct MyStruct<T> {
+}
+
+protocol MyProto {
+  associatedtype Assoc
+  func foo(x: Assoc) -> Assoc
+}
+
+#if false
+extension MyStruct {
+  #^COMPLETE_1^#
+}
+
+extension MyStruct: MyProto {
+  #^COMPLETE_2^#
+}
+#endif