Index: clang-tools-extra/clang-tidy/altera/StructPackAlignCheck.cpp
===================================================================
--- clang-tools-extra/clang-tidy/altera/StructPackAlignCheck.cpp
+++ clang-tools-extra/clang-tidy/altera/StructPackAlignCheck.cpp
@@ -51,6 +51,10 @@
   if (Struct->isTemplated())
      return;
 
+  // Ignore invalid decls to prevent crashing on calling `getASTRecordLayout`.
+  if (Struct->isInvalidDecl())
+    return;
+
   // Get sizing info for the struct.
   llvm::SmallVector<std::pair<unsigned int, unsigned int>, 10> FieldSizes;
   unsigned int TotalBitSize = 0;
Index: clang-tools-extra/test/clang-tidy/checkers/altera-struct-pack-align-invalid-decl-no-crash.cpp
===================================================================
--- /dev/null
+++ clang-tools-extra/test/clang-tidy/checkers/altera-struct-pack-align-invalid-decl-no-crash.cpp
@@ -0,0 +1,8 @@
+// RUN: %check_clang_tidy -expect-clang-tidy-error %s altera-struct-pack-align %t -- -header-filter=.*
+
+// This should not crash.
+
+struct Foo {
+  member;
+};
+// CHECK-MESSAGES: :[[@LINE-2]]:3: error: C++ requires a type specifier for all declarations [clang-diagnostic-error]