__label__ not supported

[nunoplopes]

Bugzilla Link	3429
Resolution	FIXED
Resolved on	Feb 17, 2011 22:11
Version	unspecified
OS	All
Blocks	llvm/llvm-bugzilla-archive#4068 llvm/llvm-bugzilla-archive#6815 llvm/llvm-bugzilla-archive#3696 llvm/llvm-bugzilla-archive#4151 llvm/llvm-bugzilla-archive#4220
CC	@kjwinchester,@tkremenek,@pwo

Extended Description

the following doesnt work (-fsyntax-only):

void foo() {
label l;
int v;
}

[lattner]

Don't forget fun stuff like:

void foo() {
{
label l;
l: goto l;
}
{
label l;
l: goto l;
}
}

label completely changes the scoping rules for labels :(

[nunoplopes]

*** Bug llvm/llvm-bugzilla-archive#3458 has been marked as a duplicate of this bug. ***

[lattner]

*** Bug llvm/llvm-bugzilla-archive#3543 has been marked as a duplicate of this bug. ***

[lattner]

*** Bug llvm/llvm-bugzilla-archive#3737 has been marked as a duplicate of this bug. ***

[efriedma-quic]

*** Bug llvm/llvm-bugzilla-archive#4151 has been marked as a duplicate of this bug. ***

[lattner]

*** Bug llvm/llvm-bugzilla-archive#6377 has been marked as a duplicate of this bug. ***

[llvmbot]

Is there any hope this construct will be supported in the short term? I am asking because the Linux kernel (among others) keeps using label and there is no indication the developers will not continue using it.

[llvmbot]

Our (ReactOS) Structured Exception Handling support lib (PSEH) makes use of it too, which is preventing every core module from compiling right now.

[llvmbot]

A logging library/framework I am about to publish soon depends on this feature.
Right now, I have to add #ifdefs to disable some functionality when being compiled with clang.
I'd be happy to be able to offer all features to users of XCode 4 final when it is released.

[llvmbot]

Also filed this as Bug ID# 8287027 with Apple, maybe others who depend on the feature
want to do so too and reference this id.

[llvmbot]

Our compiler team has a patch to add this GCC feature to clang including a nice AST representation, I'll aim to attach it here over the course of the week as part of our series to build the Linux kernel without modification.

[llvmbot]

(work-in-progress) rework of label support
This patch modifies adds support for label GNU locally scoped labels. It also changes ordinary labels to use the same mechanism of label declarations, which are used to track jumps. Other fixes:

• Jump diagnostics have greatly improved error recovery.
• Code completion for gotos and address-of-label expressions.
• No longer back-patches the AST with fake LabelStmts. This provides a more consistent representation of the source, especially in error recovery.
• All scope checking FIXMEs and known crashers (including jump-into-statement-expressions and VLA expressions) have been fixed.

The patch isn't quite ready to be landed yet but I thought I'd share this now.

[kjwinchester]

I get failed hunks in 7 files trying to apply the attached patch to the current clang SVN codebase. Is there a special branch where I should be applying this patch? Or is the development moving so fast that the patch has become out of date?

[llvmbot]

patch refreshed for svn 121290
I've refreshed the patch for 121290, compiles and passes basic tests. Please
note that I did just hand fix of all the rejects and direct adaptation to
latest code updates (like removing Retain() calls on Stmt) and no code review.

Alp, thanks for your work on this patch and please send updates :)

[llvmbot]

update for 122051
fixed crash in clang analyzer: missing Label case in CFGRecStmtDeclVisitor.h

[tkremenek]

Created an attachment (id=5901) [details]
update for 122051

fixed crash in clang analyzer: missing Label case in CFGRecStmtDeclVisitor.h

Is there a test case for this crash?

[llvmbot]

files that expose analyzer crash of unhandled label case in recursive visitor

[llvmbot]

Last interesting log messages:

ANALYZE: arch/x86/kernel/apic/io_apic.c setup_IO_APIC_irq_extra
clang:
/usr/src/packages/BUILD/llvm-2.9svn121697/tools/clang/lib/Analysis/../../include/clang/Analysis/Visitors/CFGRecStmtDeclVisitor.h:70:
void clang::CFGRecStmtDeclVisitor
::VisitDecl(clang::Decl*) [with ImplClass = ::RegisterDecls]: Assertion `false && "Subtype of ScopedDecl not handled."' failed.

Fixed by this:

--- include/clang/Analysis/Visitors/CFGRecStmtDeclVisitor.h (revision 122335)
+++ include/clang/Analysis/Visitors/CFGRecStmtDeclVisitor.h (working copy)
@@ -66,6 +66,7 @@
DISPATCH_CASE(Record) // FIXME: Refine. VisitStructDecl?
DISPATCH_CASE(CXXRecord)
DISPATCH_CASE(Enum)

•    DISPATCH_CASE(Label)
   default:
     assert(false && "Subtype of ScopedDecl not handled.");
  

  }
  @@ -85,6 +86,7 @@
  DEFAULT_DISPATCH(ObjCMethod)
  DEFAULT_DISPATCH(ObjCProtocol)
  DEFAULT_DISPATCH(ObjCCategory)

• DEFAULT_DISPATCH(Label)

  void VisitCXXRecordDecl(CXXRecordDecl D) {
  static_cast<ImplClass>(this)->VisitRecordDecl(D);

Obviously, the crash is caused by unhandled case due to the out-of-tree
label patch. I did not try to reduce the test case.

[lattner]

updated patch for mainline
I've updated the patch to mainline. There is a lot of goodness here, but it will require a substantial amount of work to get it in shape for submission. It fails 4 tests, primarily due to unused labels.

[lattner]

Clang now supports label on mainline, but there is still some work to get llvm/llvm-bugzilla-archive#4151 to be useful. Please file new bugs about label details that that you notice which are wrong, I'd like to claim that this is supported for LLVM 2.9

[nunoplopes]

mentioned in issue llvm/llvm-bugzilla-archive#3458

[lattner]

mentioned in issue llvm/llvm-bugzilla-archive#3543

[EdSchouten]

mentioned in issue llvm/llvm-bugzilla-archive#3696

[lattner]

mentioned in issue llvm/llvm-bugzilla-archive#3737

[edwintorok]

mentioned in issue llvm/llvm-bugzilla-archive#4068

[efriedma-quic]

mentioned in issue llvm/llvm-bugzilla-archive#4151

[efriedma-quic]

mentioned in issue llvm/llvm-bugzilla-archive#4220

[lattner]

mentioned in issue llvm/llvm-bugzilla-archive#6377

[llvmbot]

mentioned in issue llvm/llvm-bugzilla-archive#6815