On Fri, Nov 20, 2020 at 05:18:55PM -0500, Jason Merrill via Gcc-patches wrote: > On 11/16/20 9:58 PM, Marek Polacek wrote: > > [dcl.constexpr]/3 says that the function-body of a constexpr function > > shall not contain an identifier label, but we aren't enforcing that. > > > > This patch implements that. Of course, we can't reject artificial > > labels. > > > > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk? > > > > gcc/cp/ChangeLog: > > > > PR c++/97846 > > * constexpr.c (potential_constant_expression_1): Reject > > LABEL_EXPRs that use non-artifical LABEL_DECLs. > > > > gcc/testsuite/ChangeLog: > > > > PR c++/97846 > > * g++.dg/cpp1y/constexpr-label.C: New test. > > --- > > gcc/cp/constexpr.c | 9 ++++++++- > > gcc/testsuite/g++.dg/cpp1y/constexpr-label.C | 9 +++++++++ > > 2 files changed, 17 insertions(+), 1 deletion(-) > > create mode 100644 gcc/testsuite/g++.dg/cpp1y/constexpr-label.C > > > > diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c > > index e6ab5eecd68..e4fbce14065 100644 > > --- a/gcc/cp/constexpr.c > > +++ b/gcc/cp/constexpr.c > > @@ -7484,7 +7484,6 @@ potential_constant_expression_1 (tree t, bool > > want_rval, bool strict, bool now, > > case OVERLOAD: > > case TEMPLATE_ID_EXPR: > > case LABEL_DECL: > > - case LABEL_EXPR: > > case CASE_LABEL_EXPR: > > case PREDICT_EXPR: > > case CONST_DECL: > > @@ -8393,6 +8392,14 @@ potential_constant_expression_1 (tree t, bool > > want_rval, bool strict, bool now, > > return false; > > } > > + case LABEL_EXPR: > > + t = LABEL_EXPR_LABEL (t); > > + if (DECL_ARTIFICIAL (t) && DECL_IGNORED_P (t)) > > Is it useful to check DECL_IGNORED_P? I'd think we want to allow any > artificial labels, regardless of whether we're emitting debug info for them.
Not really; I only checked it because create_artificial_label sets it. I'll commit the patch without that check. > OK either way. Thanks, Marek
