Parse: Skip function bodies when delayed member parsing mode is on

Fixes <rdar://problem/47305142>.

Author: slavapestov

include/swift/Parse/Parser.h

@@ -165,7 +165,9 @@ class Parser {
 
   DelayedParsingCallbacks *DelayedParseCB = nullptr;
 
-  bool isDelayedParsingEnabled() const { return DelayedParseCB != nullptr; }
+  bool isDelayedParsingEnabled() const {
+    return DelayBodyParsing || DelayedParseCB != nullptr;
+  }
 
   void setDelayedParsingCallbacks(DelayedParsingCallbacks *DelayedParseCB) {
     this->DelayedParseCB = DelayedParseCB;

lib/Parse/ParseDecl.cpp

@@ -5401,7 +5401,8 @@ void Parser::consumeAbstractFunctionBody(AbstractFunctionDecl *AFD,
 
   BodyRange.End = PreviousLoc;
 
-  if (DelayedParseCB->shouldDelayFunctionBodyParsing(*this, AFD, Attrs,
+  if (DelayedParseCB &&
+      DelayedParseCB->shouldDelayFunctionBodyParsing(*this, AFD, Attrs,
                                                      BodyRange)) {
     State->delayFunctionBodyParsing(AFD, BodyRange,
                                     BeginParserPosition.PreviousLoc);

validation-test/compiler_scale/function_bodies.gyb

@@ -3,3 +3,35 @@
 // REQUIRES: asserts
 
 func method${N}() {}
+
+class C${N} {
+    func method${N}() {}
+}
+
+extension C${N} {
+    func otherMethod${N}() {}
+}
+
+struct S${N} {
+    func method${N}() {}
+}
+
+extension S${N} {
+    func otherMethod${N}() {}
+}
+
+enum E${N} {
+    func method${N}() {}
+}
+
+extension E${N} {
+    func otherMethod${N}() {}
+}
+
+protocol P${N} {
+    func method${N}()
+}
+
+extension P${N} {
+    func otherMethod${N}() {}
+}