Merge pull request #17633 from DougGregor/fix-apply-without-throws-set-4.2

[4.2] Ensure that apply expressions have their "throws" bit set

Author: DougGregor

lib/AST/ProtocolConformance.cpp

@@ -134,12 +134,6 @@ ProtocolConformanceRef::getTypeWitnessByName(Type type,
                                              ProtocolConformanceRef conformance,
                                              Identifier name,
                                              LazyResolver *resolver) {
-  // For an archetype, retrieve the nested type with the appropriate
-  // name. There are no conformance tables.
-  if (auto archetype = type->getAs<ArchetypeType>()) {
-    return archetype->getNestedType(name);
-  }
-
   // Find the named requirement.
   AssociatedTypeDecl *assocType = nullptr;
   auto members = conformance.getRequirement()->lookupDirect(name);
@@ -153,8 +147,15 @@ ProtocolConformanceRef::getTypeWitnessByName(Type type,
   if (!assocType)
     return nullptr;
 
-  if (conformance.isAbstract())
+  if (conformance.isAbstract()) {
+    // For an archetype, retrieve the nested type with the appropriate
+    // name. There are no conformance tables.
+    if (auto archetype = type->getAs<ArchetypeType>()) {
+      return archetype->getNestedType(name);
+    }
+
     return DependentMemberType::get(type, assocType);
+  }
 
   auto concrete = conformance.getConcrete();
   if (!concrete->hasTypeWitness(assocType, resolver)) {

lib/ClangImporter/ImportDecl.cpp

@@ -1188,6 +1188,7 @@ createDefaultConstructor(ClangImporter::Implementation &Impl,
 
   auto call = CallExpr::createImplicit(context, zeroInitializerRef, {}, {});
   call->setType(selfType);
+  call->setThrows(false);
 
   auto assign = new (context) AssignExpr(lhs, SourceLoc(), call,
                                          /*implicit*/ true);

lib/Sema/TypeCheckError.cpp

@@ -134,6 +134,9 @@ class AbstractFunction {
         fn = conversion->getSubExpr()->getValueProvidingExpr();
       } else if (auto conversion = dyn_cast<BindOptionalExpr>(fn)) {
         fn = conversion->getSubExpr()->getValueProvidingExpr();
+      // Look through optional injections
+      } else if (auto injection = dyn_cast<InjectIntoOptionalExpr>(fn)) {
+        fn = injection->getSubExpr()->getValueProvidingExpr();
       // Look through function conversions.
       } else if (auto conversion = dyn_cast<FunctionConversionExpr>(fn)) {
         fn = conversion->getSubExpr()->getValueProvidingExpr();

test/Constraints/generic_super_constraint.swift

@@ -17,3 +17,11 @@ func bar<T, U>(_ x: U, y: T) -> (Derived, Int) where U: Base<T>, U: Derived {
   // expected-error@+1{{cannot convert return expression}}
   return (x, y)
 }
+
+// SR-7551 captures a crash on this code.
+class IntegerClass : ExpressibleByIntegerLiteral, Equatable {
+  required init(integerLiteral value: Int) { }
+  static func ==(lhs: IntegerClass, rhs: IntegerClass) -> Bool { return true }
+}
+
+func foo<T: IntegerClass>(_ num: T) { let _ =  num != 0 }

validation-test/compiler_crashers_2_fixed/0165-sr5427.swift

@@ -0,0 +1,7 @@
+// RUN: %target-typecheck-verify-swift
+
+// Used to crash with: apply expression is not marked as throwing or
+// non-throwing
+struct SR5427 : Error {}
+func sr5427(op: (() throws -> Void)?) rethrows { try op?() }
+try? sr5427(op: { throw SR5427() })