Merge pull request #4872 from rudkx/rdar27680407-swift-3.0-branch

Do not recurse infinitely when type checking constructor parameters.

Author: tkremenek

lib/Sema/TypeCheckDecl.cpp

@@ -6425,17 +6425,22 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
       }
     }
 
-    // Type check the constructor parameters.
-    if (CD->isInvalid() || semaFuncParamPatterns(CD)) {
-      CD->overwriteType(ErrorType::get(TC.Context));
-      CD->setInterfaceType(ErrorType::get(TC.Context));
-      CD->setInvalid();
-    } else {
-      configureConstructorType(CD, SelfTy,
-                               CD->getParameterList(1)->getType(TC.Context));
+    {
+      CD->setIsBeingTypeChecked(true);
+      SWIFT_DEFER { CD->setIsBeingTypeChecked(false); };
+
+      // Type check the constructor parameters.
+      if (CD->isInvalid() || semaFuncParamPatterns(CD)) {
+        CD->overwriteType(ErrorType::get(TC.Context));
+        CD->setInterfaceType(ErrorType::get(TC.Context));
+        CD->setInvalid();
+      } else {
+        configureConstructorType(CD, SelfTy,
+                                 CD->getParameterList(1)->getType(TC.Context));
 
-      if (!CD->isGenericContext())
-        TC.configureInterfaceType(CD);
+        if (!CD->isGenericContext())
+          TC.configureInterfaceType(CD);
+      }
     }
 
     validateAttributes(TC, CD);

test/Sema/circular_decl_checking.swift

@@ -66,3 +66,13 @@ struct SomeStruct<A> {
   typealias A = A // expected-error {{type alias 'A' circularly references itself}}
 }
 
+// <rdar://problem/27680407> Infinite recursion when using fully-qualified associatedtype name that has not been defined with typealias
+protocol rdar27680407Proto {
+  associatedtype T // expected-note {{protocol requires nested type 'T'; do you want to add it?}}
+
+  init(value: T)
+}
+
+struct rdar27680407Struct : rdar27680407Proto { // expected-error {{type 'rdar27680407Struct' does not conform to protocol 'rdar27680407Proto'}}
+  init(value: rdar27680407Struct.T) {}
+}