[Sema][ObjC] Invalidate BlockDecl with invalid return expr & its parent BlockExpr

Invalidate BlockDecl with implicit return type, in case any of the return value exprs is invalid.
Propagating the error info up by replacing BlockExpr with a RecoveryExpr.

The idea of this fix is given by @hokein(Haojian Wu)

Fix #63863.

Differential Revision: https://reviews.llvm.org/D155396

Author: danix800

clang/docs/ReleaseNotes.rst

@@ -670,6 +670,10 @@ Bug Fixes in This Version
 - Correcly diagnose jumps into statement expressions.
   This ensures the behavior of Clang is consistent with GCC.
   (`#63682 <https://github.com/llvm/llvm-project/issues/63682>`_)
+- Invalidate BlockDecl with implicit return type, in case any of the return
+  value exprs is invalid. Propagating the error info up by replacing BlockExpr
+  with a RecoveryExpr. This fixes:
+  (`#63863 <https://github.com/llvm/llvm-project/issues/63863>_`)
 
 Bug Fixes to Compiler Builtins
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

clang/lib/Sema/SemaExpr.cpp

@@ -17159,6 +17159,9 @@ ExprResult Sema::ActOnBlockStmtExpr(SourceLocation CaretLoc,
   if (getCurFunction())
     getCurFunction()->addBlock(BD);
 
+  if (BD->isInvalidDecl())
+    return CreateRecoveryExpr(Result->getBeginLoc(), Result->getEndLoc(),
+                              {Result}, Result->getType());
   return Result;
 }
 

clang/lib/Sema/SemaStmt.cpp

@@ -3730,6 +3730,11 @@ StmtResult Sema::ActOnCapScopeReturnStmt(SourceLocation ReturnLoc,
   if (FunctionScopes.back()->FirstReturnLoc.isInvalid())
     FunctionScopes.back()->FirstReturnLoc = ReturnLoc;
 
+  if (auto *CurBlock = dyn_cast<BlockScopeInfo>(CurCap);
+      CurBlock && CurCap->HasImplicitReturnType && RetValExp &&
+      RetValExp->containsErrors())
+    CurBlock->TheDecl->setInvalidDecl();
+
   return Result;
 }
 

clang/test/AST/ast-dump-recovery.m

@@ -1,4 +1,4 @@
-// RUN: not %clang_cc1 -triple x86_64-unknown-unknown -frecovery-ast -frecovery-ast-type -ast-dump %s | FileCheck -strict-whitespace %s
+// RUN: not %clang_cc1 -triple x86_64-unknown-unknown -frecovery-ast -frecovery-ast-type -fblocks -ast-dump %s | FileCheck -strict-whitespace %s
 
 @interface Foo
 - (void)method:(int)n;
@@ -16,3 +16,11 @@ void k(Foo *foo) {
   // CHECK-NEXT:   `-DeclRefExpr {{.*}} 'foo'
   foo.undef;
 }
+
+// CHECK:      |-VarDecl {{.*}} 'int (^)()' cinit
+// CHECK-NEXT: | `-RecoveryExpr {{.*}} '<dependent type> (^)(void)' contains-errors lvalue
+// CHECK-NEXT: |   `-BlockExpr {{.*}} '<dependent type> (^)(void)'
+// CHECK-NEXT: |     `-BlockDecl {{.*}} invalid
+int (^gh63863)() = ^() {
+  return undef;
+};