From 2e7891bedd768f9fde65fb4584167ee1dadf44ed Mon Sep 17 00:00:00 2001
From: Christian Kandeler <christian.kandeler@qt.io>
Date: Wed, 28 Jul 2021 17:15:24 +0200
Subject: [PATCH] CppEditor: Fix possible crash when following typdefs

It's probably also a bug that we don't resolve the identically-named
struct correctly, but at least we don't crash anymore.

Fixes: QTCREATORBUG-26047
Change-Id: I272e76460c87906c9df23aaf7f37953b451bf1a8
Reviewed-by: Christian Stenger <christian.stenger@qt.io>
---
 src/plugins/cpptools/typehierarchybuilder.cpp | 9 +++++++--
 src/plugins/cpptools/typehierarchybuilder.h   | 5 ++++-
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/src/plugins/cpptools/typehierarchybuilder.cpp b/src/plugins/cpptools/typehierarchybuilder.cpp
index 67f4e6a1ab0..c2856011429 100644
--- a/src/plugins/cpptools/typehierarchybuilder.cpp
+++ b/src/plugins/cpptools/typehierarchybuilder.cpp
@@ -146,7 +146,9 @@ TypeHierarchy TypeHierarchyBuilder::buildDerivedTypeHierarchy(QFutureInterfaceBa
     return hierarchy;
 }
 
-LookupItem TypeHierarchyBuilder::followTypedef(const LookupContext &context, const Name *symbolName, Scope *enclosingScope)
+LookupItem TypeHierarchyBuilder::followTypedef(const LookupContext &context, const Name *symbolName,
+                                               Scope *enclosingScope,
+                                               std::set<const Symbol *> typedefs)
 {
     QList<LookupItem> items = context.lookup(symbolName, enclosingScope);
 
@@ -159,6 +161,8 @@ LookupItem TypeHierarchyBuilder::followTypedef(const LookupContext &context, con
             continue;
         if (!s->isClass() && !s->isTemplate() && !s->isTypedef())
             continue;
+        if (!typedefs.insert(s).second)
+            continue;
         actualBaseSymbol = s;
         matchingItem = item;
         break;
@@ -173,7 +177,8 @@ LookupItem TypeHierarchyBuilder::followTypedef(const LookupContext &context, con
             // Anonymous aggregate such as: typedef struct {} Empty;
             return LookupItem();
         }
-        return followTypedef(context, namedType->name(), actualBaseSymbol->enclosingScope());
+        return followTypedef(context, namedType->name(), actualBaseSymbol->enclosingScope(),
+                             typedefs);
     }
 
     return matchingItem;
diff --git a/src/plugins/cpptools/typehierarchybuilder.h b/src/plugins/cpptools/typehierarchybuilder.h
index 38fc45bcf9e..38920b4cead 100644
--- a/src/plugins/cpptools/typehierarchybuilder.h
+++ b/src/plugins/cpptools/typehierarchybuilder.h
@@ -34,6 +34,8 @@
 #include <QList>
 #include <QSet>
 
+#include <set>
+
 namespace CPlusPlus {
 class LookupContext;
 class LookupItem;
@@ -72,7 +74,8 @@ public:
                                             const CPlusPlus::Snapshot &snapshot);
     static CPlusPlus::LookupItem followTypedef(const CPlusPlus::LookupContext &context,
                                                const CPlusPlus::Name *symbolName,
-                                               CPlusPlus::Scope *enclosingScope);
+                                               CPlusPlus::Scope *enclosingScope,
+                                               std::set<const CPlusPlus::Symbol *> typedefs = {});
 private:
     TypeHierarchyBuilder() = default;
     void buildDerived(QFutureInterfaceBase &futureInterface, TypeHierarchy *typeHierarchy,