Index: clang/lib/AST/Comment.cpp
===================================================================
--- clang/lib/AST/Comment.cpp
+++ clang/lib/AST/Comment.cpp
@@ -112,7 +112,8 @@
   return true;
 }
 
-static TypeLoc lookThroughTypedefOrTypeAliasLocs(TypeLoc &SrcTL) {
+static TypeLoc lookThroughTypedefOrTypeAliasLocs(TypeLoc &SrcTL,
+                                                 bool testTypedefTypeLoc) {
   TypeLoc TL = SrcTL.IgnoreParens();
 
   // Look through attribute types.
@@ -136,15 +137,22 @@
     return MemberPointerTL.getPointeeLoc().getUnqualifiedLoc();
   if (ElaboratedTypeLoc ETL = TL.getAs<ElaboratedTypeLoc>())
     return ETL.getNamedTypeLoc();
+  if (testTypedefTypeLoc)
+    if (TypedefTypeLoc TTL = TL.getAs<TypedefTypeLoc>()) {
+      TypedefNameDecl *TND = TTL.getTypedefNameDecl();
+      if (const TypeSourceInfo *TSI = TND->getTypeSourceInfo())
+        return TSI->getTypeLoc().getUnqualifiedLoc();
+    }
 
   return TL;
 }
 
-static bool getFunctionTypeLoc(TypeLoc TL, FunctionTypeLoc &ResFTL) {
+static bool getFunctionTypeLoc(TypeLoc TL, FunctionTypeLoc &ResFTL,
+                               bool testTypedefTypeLoc = false) {
   TypeLoc PrevTL;
   while (PrevTL != TL) {
     PrevTL = TL;
-    TL = lookThroughTypedefOrTypeAliasLocs(TL);
+    TL = lookThroughTypedefOrTypeAliasLocs(TL, testTypedefTypeLoc);
   }
 
   if (FunctionTypeLoc FTL = TL.getAs<FunctionTypeLoc>()) {
@@ -293,7 +301,10 @@
     if (TSI) {
       TypeLoc TL = TSI->getTypeLoc().getUnqualifiedLoc();
       FunctionTypeLoc FTL;
-      if (getFunctionTypeLoc(TL, FTL)) {
+      // Need to look through the typedef when
+      // Sema::isFunctionOrBlockPointerVarLikeDecl found a FunctionPointerType
+      // or a BlockPointerType else the ReturnType will not be set.
+      if (getFunctionTypeLoc(TL, FTL, true)) {
         ParamVars = FTL.getParams();
         ReturnType = FTL.getReturnLoc().getType();
       }
Index: clang/lib/AST/CommentSema.cpp
===================================================================
--- clang/lib/AST/CommentSema.cpp
+++ clang/lib/AST/CommentSema.cpp
@@ -588,6 +588,8 @@
   if (isObjCPropertyDecl())
     return;
   if (isFunctionDecl() || isFunctionOrBlockPointerVarLikeDecl()) {
+    assert(!ThisDeclInfo->ReturnType.isNull() &&
+           "should have a valid return type");
     if (ThisDeclInfo->ReturnType->isVoidType()) {
       unsigned DiagKind;
       switch (ThisDeclInfo->CommentDecl->getKind()) {
Index: clang/test/Sema/warn-documentation.cpp
===================================================================
--- clang/test/Sema/warn-documentation.cpp
+++ clang/test/Sema/warn-documentation.cpp
@@ -1362,3 +1362,30 @@
  */
 class EmptyNoteNoCrash {
 };
+
+namespace PR42844 { // Assertion failures when using typedefed function pointers
+typedef void (*AA)();
+typedef AA A();
+A *a1; ///< \return none
+A a2;  ///< \return none
+
+typedef int B();
+B *b; ///< \return none
+
+typedef void C();
+C *c; ///< \return none
+// expected-warning@-1 {{'\return' command used in a comment that is attached to a function returning void}}
+
+using DD = void(*)();
+using D = DD();
+D *d1; ///< \return none
+D d2;  ///< \return none
+
+using E = int();
+E *e; ///< \return none
+
+using F = void();
+F *f; ///< \return none
+// expected-warning@-1 {{'\return' command used in a comment that is attached to a function returning void}}
+
+} // namespace PR42844
Index: clang/test/Sema/warn-documentation.m
===================================================================
--- clang/test/Sema/warn-documentation.m
+++ clang/test/Sema/warn-documentation.m
@@ -310,3 +310,10 @@
  * now should work too.
  */
 typedef void (^VariadicBlockType)(int a, ...);
+
+// PR42844 - Assertion failures when using typedefed block pointers
+typedef void(^VoidBlockType)();
+typedef VoidBlockType VoidBlockTypeCall();
+VoidBlockTypeCall *d; ///< \return none
+VoidBlockTypeCall ^e; ///< \return none
+VoidBlockTypeCall f;  ///< \return none