From 882dd60aad7e7718f9cc067baab3ca725f061e10 Mon Sep 17 00:00:00 2001
From: Christian Kandeler <christian.kandeler@qt.io>
Date: Tue, 3 Nov 2020 14:25:46 +0100
Subject: [PATCH] C++: Extend alias declaration support in built-in parser

The type-id in an alias declaration can also define a new type.

Change-Id: I65dc397d2526c56334676c6ab522564f6748d594
Task-number: QTCREATORBUG-24875
Reviewed-by: Christian Stenger <christian.stenger@qt.io>
---
 src/libs/3rdparty/cplusplus/Parser.cpp        | 19 ++++++++++++++++---
 .../auto/cplusplus/cxx11/data/aliasDecl.1.cpp |  2 ++
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/src/libs/3rdparty/cplusplus/Parser.cpp b/src/libs/3rdparty/cplusplus/Parser.cpp
index 3c509be00c0..1550c8b31d8 100644
--- a/src/libs/3rdparty/cplusplus/Parser.cpp
+++ b/src/libs/3rdparty/cplusplus/Parser.cpp
@@ -1527,10 +1527,23 @@ bool Parser::parseDeclSpecifierSeq(SpecifierListAST *&decl_specifier_seq,
         } else if (! onlySimpleTypeSpecifiers && ! has_type_specifier &&
                    (LA() == T_TYPENAME || LA() == T_ENUM || lookAtClassKey())) {
             // typename-specifier, elaborated-type-specifier
-            int startOfElaboratedTypeSpecifier = cursor();
+            int startOfTypeSpecifier = cursor();
             if (! parseElaboratedTypeSpecifier(*decl_specifier_seq_ptr)) {
-                error(startOfElaboratedTypeSpecifier, "expected an elaborated type specifier");
-                break;
+                rewind(startOfTypeSpecifier);
+                if (LA() == T_ENUM) {
+                    if (!parseEnumSpecifier(*decl_specifier_seq_ptr)) {
+                        error(startOfTypeSpecifier, "expected an enum specifier");
+                        break;
+                    }
+                } else if (lookAtClassKey()) {
+                    if (!parseClassSpecifier(*decl_specifier_seq_ptr)) {
+                        error(startOfTypeSpecifier, "expected a class specifier");
+                        break;
+                    }
+                } else {
+                    error(startOfTypeSpecifier, "expected an elaborated type specifier");
+                    break;
+                }
             }
             decl_specifier_seq_ptr = &(*decl_specifier_seq_ptr)->next;
             has_type_specifier = true;
diff --git a/tests/auto/cplusplus/cxx11/data/aliasDecl.1.cpp b/tests/auto/cplusplus/cxx11/data/aliasDecl.1.cpp
index 99384acaa17..50c6312a790 100644
--- a/tests/auto/cplusplus/cxx11/data/aliasDecl.1.cpp
+++ b/tests/auto/cplusplus/cxx11/data/aliasDecl.1.cpp
@@ -2,3 +2,5 @@ using Foo = int;
 using Bar = std::vector<int>::value_type;
 using A [[foo]] = const float;
 using B alignas(void*) = C *;
+using C = struct {};
+using D = enum class E {A, B};