[SILOpt] Don't do callee analysis on destructors of imported classes. (#6313)

If by chance we haven't imported the members of a particular class,
SIL should not fault them in if at all possible.

The test case was a pain to come up with; it involves a class using
a forward-declared protocol that's actually defined in Swift /in a
non-primary file/, where that protocol is never mentioned in the
primary file and the class's members are never accessed otherwise.

rdar://problem/29535170

Author: jrose-apple

lib/SILOptimizer/Analysis/BasicCalleeAnalysis.cpp

@@ -75,6 +75,8 @@ CalleeCache::getOrCreateCalleesForMethod(SILDeclRef Decl) {
 /// Update the callees for each method of a given class, along with
 /// all the overridden methods from superclasses.
 void CalleeCache::computeClassMethodCalleesForClass(ClassDecl *CD) {
+  assert(!CD->hasClangNode());
+
   for (auto *Member : CD->getMembers()) {
     auto *AFD = dyn_cast<AbstractFunctionDecl>(Member);
     if (!AFD)
@@ -229,7 +231,7 @@ CalleeList CalleeCache::getCalleeList(SILInstruction *I) const {
                                     ->getAnyOptionalObjectType()
                                     .getCanonicalTypeOrNull());
   auto Class = Ty.getSwiftRValueType().getClassOrBoundGenericClass();
-  if (!Class || !Class->hasDestructor())
+  if (!Class || Class->hasClangNode() || !Class->hasDestructor())
     return CalleeList();
   auto Destructor = Class->getDestructor();
   return getCalleeList(Destructor);

test/ClangImporter/MixedSource/Inputs/mixed-target/header.h

@@ -7,7 +7,10 @@
 #import "used-by-both-headers.h"
 
 @class ForwardClass;
+@protocol ForwardProto;
+
 void doSomething(ForwardClass *arg);
+void doSomethingProto(id <ForwardProto> arg);
 
 @interface Base
 - (NSObject *)safeOverride:(ForwardClass *)arg;
@@ -21,9 +24,6 @@ void doSomething(ForwardClass *arg);
 @end
 
 
-@protocol ForwardProto;
-void doSomethingProto(id <ForwardProto> arg);
-
 @interface Base ()
 - (NSObject *)safeOverrideProto:(id <ForwardProto>)arg;
 - (NSObject *)unsafeOverrideProtoParam:(NSObject *)arg;
@@ -69,3 +69,9 @@ typedef int NameInProtocol;
 @interface WrapperInterface (Category)
 typedef int NameInCategory;
 @end
+
+
+@protocol ForwardProtoFromOtherFile;
+@interface ClassThatHasAProtocolTypedPropertyButMembersAreNeverLoaded
+@property (weak) id <ForwardProtoFromOtherFile> weakProtoProp;
+@end

test/ClangImporter/MixedSource/Inputs/mixed-target/other-file.swift

@@ -0,0 +1 @@
+@objc protocol ForwardProtoFromOtherFile {}

test/ClangImporter/MixedSource/mixed-target-using-header.swift

@@ -1,4 +1,5 @@
-// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -I %S/../Inputs/custom-modules -import-objc-header %S/Inputs/mixed-target/header.h -typecheck %s -disable-objc-attr-requires-foundation-module -verify
+// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -I %S/../Inputs/custom-modules -import-objc-header %S/Inputs/mixed-target/header.h -typecheck -primary-file %s %S/Inputs/mixed-target/other-file.swift -disable-objc-attr-requires-foundation-module -verify
+// RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -I %S/../Inputs/custom-modules -import-objc-header %S/Inputs/mixed-target/header.h -emit-sil -primary-file %s %S/Inputs/mixed-target/other-file.swift -disable-objc-attr-requires-foundation-module -o /dev/null -D SILGEN
 
 // REQUIRES: objc_interop
 
@@ -37,17 +38,21 @@ class ProtoConformer : ForwardClassUser {
 func testProtocolWrapper(_ conformer: ForwardClassUser) {
   conformer.consumeForwardClass(conformer.forward)
 }
-testProtocolWrapper(ProtoConformer())
+func useProtocolWrapper() {
+  testProtocolWrapper(ProtoConformer())
+}
 
 func testStruct(_ p: Point2D) -> Point2D {
   var result = p
   result.y += 5
   return result
 }
 
+#if !SILGEN
 func testSuppressed() {
   let _: __int128_t? = nil // expected-error{{use of undeclared type '__int128_t'}}
 }
+#endif
 
 func testMacro() {
   _ = CONSTANT as CInt
@@ -58,6 +63,7 @@ func testFoundationOverlay() {
   _ = NSUTF8StringEncoding as UInt // and we should get the overlay version
 }
 
+#if !SILGEN
 func testProtocolNamingConflict() {
   let a: ConflictingName1?
   var b: ConflictingName1Protocol?
@@ -69,9 +75,13 @@ func testProtocolNamingConflict() {
   d = c // expected-error {{cannot assign value of type 'ConflictingName2?' to type 'ConflictingName2Protocol?'}}
   _ = d
 }
+#endif
 
 func testDeclsNestedInObjCContainers() {
   let _: NameInInterface = 0
   let _: NameInProtocol = 0
   let _: NameInCategory = 0
 }
+
+func testReleaseClassWhoseMembersAreNeverLoaded(
+    obj: ClassThatHasAProtocolTypedPropertyButMembersAreNeverLoaded) {}