Support nil completions in @objcImpl async methods

An async @objc method only checks if its completion handler parameter is null if ClangImporter forces it to. This is fine for @objc with a generated header, because the generated header always declares the parameter _Nonnull, but clients ignore that annotation and pass nil anyway often enough that for @objc @implementation, we ought to be defensive.

We can achieve this by simply making the completion handler’s type Optional—SILGen already looks for this and knows what to do when it sees it.

Fixes rdar://130527373.

Author: beccadax

Diff for: lib/Sema/TypeCheckDeclObjC.cpp

@@ -869,6 +869,10 @@ bool swift::isRepresentableInObjC(
         ASTExtInfoBuilder(FunctionTypeRepresentation::Block, false, Type())
           .build());
 
+    // @objcImpl member implementations need to allow a nil completion handler.
+    if (AFD->isObjCMemberImplementation())
+      completionHandlerType = OptionalType::get(completionHandlerType);
+
     asyncConvention = ForeignAsyncConvention(
         completionHandlerType->getCanonicalType(), completionHandlerParamIndex,
         completionHandlerErrorParamIndex,

Diff for: test/IRGen/Inputs/objc_implementation.h

@@ -8,6 +8,8 @@
 
 - (void)mainMethod:(int)param;
 
+- (void)asyncMethodWithCompletionHandler:(void (^ _Nullable)(void))completion;
+
 @end
 
 @interface ImplClass () <NSMutableCopying>

Diff for: test/IRGen/objc_implementation.swift

@@ -23,11 +23,12 @@
 
 // Class
 // CHECK: [[selector_data__cxx_destruct:@[^, ]+]] = private global [14 x i8] c".cxx_destruct\00", section "__TEXT,__objc_methname,cstring_literals", align 1
-// CHECK-LABEL: @_INSTANCE_METHODS_ImplClass = internal constant { i32, i32, [9 x { ptr, ptr, ptr }] } { i32 24, i32 9, [9 x { ptr, ptr, ptr }] [
+// CHECK-LABEL: @_INSTANCE_METHODS_ImplClass = internal constant { i32, i32, [10 x { ptr, ptr, ptr }] } { i32 24, i32 10, [10 x { ptr, ptr, ptr }] [
 // CHECK-SAME: { ptr, ptr, ptr } { ptr @"\01L_selector_data(init)", ptr @".str.7.@16@0:8", ptr @"$sSo9ImplClassC19objc_implementationEABycfcTo{{(\.ptrauth)?}}" }
 // CHECK-SAME: { ptr, ptr, ptr } { ptr @"\01L_selector_data(implProperty)", ptr @".str.7.i16@0:8", ptr @"$sSo9ImplClassC19objc_implementationE12implPropertys5Int32VvgTo{{(\.ptrauth)?}}" }
 // CHECK-SAME: { ptr, ptr, ptr } { ptr @"\01L_selector_data(setImplProperty:)", ptr @".str.10.v20@0:8i16", ptr @"$sSo9ImplClassC19objc_implementationE12implPropertys5Int32VvsTo{{(\.ptrauth)?}}" }
 // CHECK-SAME: { ptr, ptr, ptr } { ptr @"\01L_selector_data(mainMethod:)", ptr @".str.10.v20@0:8i16", ptr @"$sSo9ImplClassC19objc_implementationE10mainMethodyys5Int32VFTo{{(\.ptrauth)?}}" }
+// CHECK-SAME: { ptr, ptr, ptr } { ptr @"\01L_selector_data(asyncMethodWithCompletionHandler:)", ptr @".str.16.v24@0:8@?<v@?>16", ptr @"$sSo9ImplClassC19objc_implementationE11asyncMethodyyYaFTo{{(\.ptrauth)?}}" }
 // CHECK-SAME: { ptr, ptr, ptr } { ptr @"\01L_selector_data(extensionMethod:)", ptr @".str.10.v20@0:8i16", ptr @"$sSo9ImplClassC19objc_implementationE15extensionMethodyys5Int32VFTo{{(\.ptrauth)?}}" }
 // CHECK-SAME: { ptr, ptr, ptr } { ptr @"\01L_selector_data(copyWithZone:)", ptr @".str.11.@24@0:8^v16", ptr @"$sSo9ImplClassC19objc_implementationE4copy4withypSg10ObjectiveC6NSZoneVSg_tFTo{{(\.ptrauth)?}}" }
 // CHECK-SAME: { ptr, ptr, ptr } { ptr @"\01L_selector_data(mutableCopyWithZone:)", ptr @".str.11.@24@0:8^v16", ptr @"$sSo9ImplClassC19objc_implementationE11mutableCopy4withypSg10ObjectiveC6NSZoneVSg_tFTo{{(\.ptrauth)?}}" }
@@ -61,6 +62,7 @@
   final var implProperty2: NSObject?
 
   @objc func mainMethod(_: Int32) { print(implProperty) }
+  @objc func asyncMethod() async {}
   @objc func extensionMethod(_: Int32) {}
 
   @objc(copyWithZone:)
@@ -130,7 +132,6 @@
 
 // Swift metadata
 // CHECK: @"$s19objc_implementationMXM" = linkonce_odr hidden constant <{ i32, i32, i32 }> <{ i32 0, i32 0, i32 trunc (i64 sub (i64 ptrtoint (ptr @.str.19.objc_implementation to i64), i64 ptrtoint (ptr getelementptr inbounds (<{ i32, i32, i32 }>, ptr @"$s19objc_implementationMXM", i32 0, i32 2) to i64)) to i32) }>, section "__TEXT,__constg_swiftt", align 4
-// CHECK: @"symbolic So9ImplClassC" = linkonce_odr hidden constant <{ [13 x i8], i8 }> <{ [13 x i8] c"So9ImplClassC", i8 0 }>, section "__TEXT,__swift5_typeref, regular"{{.*}}, align 2
 // CHECK: @"$s19objc_implementation13SwiftSubclassCMn" = constant <{ i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 }> <{ i32 80, i32 trunc (i64 sub (i64 ptrtoint (ptr @"$s19objc_implementationMXM" to i64), i64 ptrtoint (ptr getelementptr inbounds (<{ i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 }>, ptr @"$s19objc_implementation13SwiftSubclassCMn", i32 0, i32 1) to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint (ptr @.str.13.SwiftSubclass to i64), i64 ptrtoint (ptr getelementptr inbounds (<{ i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 }>, ptr @"$s19objc_implementation13SwiftSubclassCMn", i32 0, i32 2) to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint (ptr @"$s19objc_implementation13SwiftSubclassCMa" to i64), i64 ptrtoint (ptr getelementptr inbounds (<{ i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 }>, ptr @"$s19objc_implementation13SwiftSubclassCMn", i32 0, i32 3) to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint (ptr @"$s19objc_implementation13SwiftSubclassCMF" to i64), i64 ptrtoint (ptr getelementptr inbounds (<{ i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 }>, ptr @"$s19objc_implementation13SwiftSubclassCMn", i32 0, i32 4) to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint (ptr @"symbolic So9ImplClassC" to i64), i64 ptrtoint (ptr getelementptr inbounds (<{ i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 }>, ptr @"$s19objc_implementation13SwiftSubclassCMn", i32 0, i32 5) to i64)) to i32), i32 3, i32 10, i32 0, i32 0, i32 10 }>, section "__TEXT,__constg_swiftt", align 4
 // CHECK: @"$s19objc_implementation13SwiftSubclassCMf" = internal global <{ ptr, ptr, ptr, i64, ptr, ptr, ptr, i64, i32, i32, i32, i16, i16, i32, i32, ptr, ptr }> <{ ptr null, ptr @"$s19objc_implementation13SwiftSubclassCfD", ptr @"$sBOWV", i64 ptrtoint (ptr @"OBJC_METACLASS_$__TtC19objc_implementation13SwiftSubclass" to i64), ptr @"OBJC_CLASS_$_ImplClass", ptr @_objc_empty_cache, ptr null, i64 add (i64 ptrtoint (ptr @_DATA__TtC19objc_implementation13SwiftSubclass to i64), i64 2), i32 0, i32 0, i32 24, i16 7, i16 0, i32 104, i32 24, ptr @"$s19objc_implementation13SwiftSubclassCMn", ptr null }>, section "__DATA,__objc_data, regular", align 8
 // CHECK: @"symbolic _____ 19objc_implementation13SwiftSubclassC" = linkonce_odr hidden constant <{ i8, i32, i8 }> <{ i8 1, i32 trunc (i64 sub (i64 ptrtoint (ptr @"$s19objc_implementation13SwiftSubclassCMn" to i64), i64 ptrtoint (ptr getelementptr inbounds (<{ i8, i32, i8 }>, ptr @"symbolic _____ 19objc_implementation13SwiftSubclassC", i32 0, i32 1) to i64)) to i32), i8 0 }>, section "__TEXT,__swift5_typeref, regular"{{.*}}, align 2
@@ -237,6 +238,33 @@ public func fn(impl: ImplClass, swiftSub: SwiftSubclass) {
 // ObjC calling convention -[ImplClass mainMethod:]
 // CHECK-LABEL: define internal void @"$sSo9ImplClassC19objc_implementationE10mainMethodyys5Int32VFTo"
 
+// Swift calling convention -[ImplClass asyncMethodWithCompletion:]
+// CHECK-LABEL: define hidden swifttailcc void @"$sSo9ImplClassC19objc_implementationE11asyncMethodyyYaF"
+
+// ObjC calling convention -[ImplClass asyncMethodWithCompletion:]
+// CHECK-LABEL: define internal void @"$sSo9ImplClassC19objc_implementationE11asyncMethodyyYaFTo"
+// CHECK: call swiftcc void @"$ss29_runTaskForBridgedAsyncMethodyyyyYaYbcnF"(ptr @"$sSo9ImplClassC19objc_implementationE11asyncMethodyyYaFyyYacfU_To{{[^"]*}}"
+
+// ObjC calling convention -[ImplClass asyncMethodWithCompletion:] (start of helper closure)
+// CHECK-LABEL: define linkonce_odr hidden swifttailcc void @"$sSo9ImplClassC19objc_implementationE11asyncMethodyyYaFyyYacfU_To"
+// CHECK: musttail call swifttailcc void @"$sSo9ImplClassC19objc_implementationE11asyncMethodyyYaF"
+
+// ObjC calling convention -[ImplClass asyncMethodWithCompletion:] (end of helper closure)
+// CHECK-LABEL: define internal swifttailcc void @"$sSo9ImplClassC19objc_implementationE11asyncMethodyyYaFyyYacfU_ToTQ0_"
+
+// Make sure this function incorporates a nil check
+// CHECK: [[IS_COMPLETION_NULL:%[0-9]+]] = icmp eq i64 {{%\.reload[0-9+]}}, 0
+// CHECK: br i1 [[IS_COMPLETION_NULL]], label %[[FINISH:[^,]+]], label %[[RUN_COMPLETION:[^,]+]]
+// CHECK: [[RUN_COMPLETION]]:
+
+// The actual call to the block
+// CHECK: call void {{%[0-9]+}}
+
+// Final control flow for the nil check
+// CHECK: br label %[[FINISH]]
+// CHECK: [[FINISH]]:
+// CHECK: ret void
+
 // Swift calling convention -[ImplClass extensionMethod:]
 // CHECK-LABEL: define hidden swiftcc void @"$sSo9ImplClassC19objc_implementationE15extensionMethodyys5Int32VF"