Endless loop in Sema::ArgumentDependentLookup

[Alexander Potapenko]

See http://llvm.org/bugs/show_bug.cgi?id=16597
The fix proposed by Richard is below, however yours looks more
correct, as D is never changed in that loop.

Index: lib/Sema/SemaLookup.cpp
===================================================================
--- lib/Sema/SemaLookup.cpp     (revision 186060)
+++ lib/Sema/SemaLookup.cpp     (working copy)
@@ -2751,6 +2751,7 @@
     //        namespaces even if they are not visible during an ordinary
     //        lookup (11.4).
     DeclContext::lookup_result R = (*NS)->lookup(Name);
+    llvm::SmallPtrSet<Decl*, 8> VisitedFriendDecls;
     for (DeclContext::lookup_iterator I = R.begin(), E = R.end(); I != E;
          ++I) {
       NamedDecl *D = *I;
@@ -2759,6 +2760,8 @@
       if (D->getIdentifierNamespace() == Decl::IDNS_OrdinaryFriend) {
         bool DeclaredInAssociatedClass = false;
         for (Decl *DI = D; DI; DI = D->getPreviousDecl()) {
+          if (!VisitedFriendDecls.insert(DI))
+            break;
           DeclContext *LexDC = DI->getLexicalDeclContext();
           if (AssociatedClasses.count(cast<CXXRecordDecl>(LexDC))) {
             DeclaredInAssociatedClass = true;

On Fri, Jul 12, 2013 at 3:38 PM, Stephan Bergmann <sbergman at redhat.com> wrote:
> Looks like trunk r186040 introduced a typo in lib/Sema/SemaLookup.cpp that
> can cause endless loops, fix would apparently be:
>
>> Index: lib/Sema/SemaLookup.cpp
>> ===================================================================
>> --- lib/Sema/SemaLookup.cpp     (revision 186153)
>> +++ lib/Sema/SemaLookup.cpp     (working copy)
>> @@ -2758,7 +2758,7 @@
>>        // it only if it was declared in an associated classes.
>>        if (D->getIdentifierNamespace() == Decl::IDNS_OrdinaryFriend) {
>>          bool DeclaredInAssociatedClass = false;
>> -        for (Decl *DI = D; DI; DI = D->getPreviousDecl()) {
>> +        for (Decl *DI = D; DI; DI = DI->getPreviousDecl()) {
>>            DeclContext *LexDC = DI->getLexicalDeclContext();
>>            if (AssociatedClasses.count(cast<CXXRecordDecl>(LexDC))) {
>>              DeclaredInAssociatedClass = true;
>
>
> Stephan
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-- 
Alexander Potapenko
Software Engineer
Google Moscow