[cfe-commits] r162835 - in /cfe/trunk: lib/AST/ExprConstant.cpp test/Sema/init.c

[Richard Smith]

On Wed, Aug 29, 2012 at 1:44 AM, Hans Wennborg <hans at hanshq.net> wrote:

> Author: hans
> Date: Wed Aug 29 03:44:49 2012
> New Revision: 162835
>
> URL: http://llvm.org/viewvc/llvm-project?rev=162835&view=rev
> Log:
> The address of a TLS var is not compile-time constant (PR13720)
>
> This makes Clang produce an error for code such as:
>
>   __thread int x;
>   int *p = &x;
>
> The lvalue of a thread-local variable cannot be evaluated at compile
> time.
>
> Modified:
>     cfe/trunk/lib/AST/ExprConstant.cpp
>     cfe/trunk/test/Sema/init.c
>
> Modified: cfe/trunk/lib/AST/ExprConstant.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/ExprConstant.cpp?rev=162835&r1=162834&r2=162835&view=diff
>
> ==============================================================================
> --- cfe/trunk/lib/AST/ExprConstant.cpp (original)
> +++ cfe/trunk/lib/AST/ExprConstant.cpp Wed Aug 29 03:44:49 2012
> @@ -2832,6 +2832,8 @@
>  }
>
>  bool LValueExprEvaluator::VisitVarDecl(const Expr *E, const VarDecl *VD) {
> +  if (VD->isThreadSpecified())
> +    return false;
>

That should be 'return Error(E);' (constant expression evaluation shouldn't
fail without producing a diagnostic). As a testcase, we should reject this:

__thread int n;
constexpr int &f() { return n; }
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