AST: Prohibit archetypes in setInterfaceType()

Author: slavapestov

lib/AST/Decl.cpp

@@ -1705,6 +1705,13 @@ Type ValueDecl::getInterfaceType() const {
 void ValueDecl::setInterfaceType(Type type) {
   assert((type.isNull() || !type->hasTypeVariable()) &&
          "Type variable in interface type");
+
+  // lldb creates global typealiases with archetypes in them.
+  // FIXME: Add an isDebugAlias() flag, like isDebugVar().
+  if (!isa<TypeAliasDecl>(this)) {
+    assert((type.isNull() || !type->hasArchetype()) &&
+           "Archetype in interface type");
+  }
 
   InterfaceTy = type;
 }

lib/Sema/TypeCheckConstraints.cpp

@@ -2283,7 +2283,8 @@ bool TypeChecker::typeCheckExprPattern(ExprPattern *EP, DeclContext *DC,
                                          Context.getIdentifier("$match"),
                                          rhsType,
                                          DC);
-  matchVar->setInterfaceType(rhsType);
+  matchVar->setInterfaceType(ArchetypeBuilder::mapTypeOutOfContext(
+      DC, rhsType));
 
   matchVar->setImplicit();
   EP->setMatchVar(matchVar);

lib/Sema/TypeCheckPattern.cpp

@@ -971,7 +971,7 @@ static bool coercePatternViaConditionalDowncast(TypeChecker &tc,
                                             pattern->getLoc(),
                                             tc.Context.getIdentifier("$match"),
                                             type, dc);
-  matchVar->setInterfaceType(type);
+  matchVar->setInterfaceType(ArchetypeBuilder::mapTypeOutOfContext(dc, type));
   matchVar->setHasNonPatternBindingInit();
 
   // Form the cast $match as? T, which produces an optional.

lib/Sema/TypeCheckStmt.cpp

@@ -664,7 +664,8 @@ class StmtChecker : public StmtVisitor<StmtChecker, Stmt*> {
       generator = new (TC.Context)
         VarDecl(/*static*/ false, /*IsLet*/ false, S->getInLoc(),
                 TC.Context.getIdentifier(name), generatorTy, DC);
-      generator->setInterfaceType(generatorTy);
+      generator->setInterfaceType(ArchetypeBuilder::mapTypeOutOfContext(
+          DC, generatorTy));
       generator->setImplicit();
 
       // Create a pattern binding to initialize the generator.

lib/Serialization/Serialization.cpp

@@ -2521,12 +2521,15 @@ void Serializer::writeDecl(const Decl *D) {
     verifyAttrSerializable(param);
 
     auto contextID = addDeclContextRef(param->getDeclContext());
-    Type type = (param->hasType()
-                 ? param->getType()
-                 : Type());
-    Type interfaceType = (param->hasInterfaceType()
-                          ? param->getInterfaceType()
-                          : Type());
+    Type type, interfaceType;
+
+    if (param->hasType()) {
+      type = param->getType();
+      interfaceType = param->getInterfaceType();
+      // FIXME: Interface types for ParamDecls
+      if (interfaceType->hasArchetype())
+        interfaceType = Type();
+    }
 
     unsigned abbrCode = DeclTypeAbbrCodes[ParamLayout::Code];
     ParamLayout::emitRecord(Out, ScratchRecord, abbrCode,