diff --git a/clang/lib/Sema/SemaStmt.cpp b/clang/lib/Sema/SemaStmt.cpp
--- a/clang/lib/Sema/SemaStmt.cpp
+++ b/clang/lib/Sema/SemaStmt.cpp
@@ -2434,8 +2434,11 @@
     QualType RangeType = Range->getType();
 
     if (RequireCompleteType(RangeLoc, RangeType,
-                            diag::err_for_range_incomplete_type))
+                            diag::err_for_range_incomplete_type)) {
+      if (LoopVar->getType()->isUndeducedType())
+        LoopVar->setInvalidDecl();
       return StmtError();
+    }
 
     // Build auto __begin = begin-expr, __end = end-expr.
     // Divide by 2, since the variables are in the inner scope (loop body).
diff --git a/clang/test/SemaCXX/for-range-crash.cpp b/clang/test/SemaCXX/for-range-crash.cpp
new file mode 100644
--- /dev/null
+++ b/clang/test/SemaCXX/for-range-crash.cpp
@@ -0,0 +1,10 @@
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++17 %s
+
+template <typename>
+class Bar {
+  Bar<int> *variables_to_modify;
+  foo() { // expected-error {{C++ requires a type specifier for all declarations}}
+    for (auto *c : *variables_to_modify)
+      delete c;
+  }
+};