On Thu, Nov 17, 2022 at 09:42:18AM -0500, Jason Merrill wrote: > > --- gcc/cp/constexpr.cc.jj 2022-11-17 08:48:30.530357181 +0100 > > +++ gcc/cp/constexpr.cc 2022-11-17 09:56:50.479522863 +0100 > > @@ -7098,7 +7098,8 @@ cxx_eval_constant_expression (const cons > > && (TREE_STATIC (r) > > || (CP_DECL_THREAD_LOCAL_P (r) && !DECL_REALLY_EXTERN (r))) > > /* Allow __FUNCTION__ etc. */ > > - && !DECL_ARTIFICIAL (r)) > > + && !DECL_ARTIFICIAL (r) > > + && (cxx_dialect < cxx20 || !decl_constant_var_p (r))) > > I don't think we need to check cxx_dialect here since > diagnose_static_in_constexpr will have already complained.
I thought for older C++ this is to catch void foo () { constexpr int a = ({ static constexpr int b = 2; b; }); } and for C++23 the only 3 spots that diagnose those. But perhaps for C++20 or older we can check if the var has a context of a constexpr function (then assume cp_finish_decl errored or pedwarned already) and only error or pedwarn otherwise. > > > { > > if (!ctx->quiet) > > { > > @@ -9588,7 +9589,12 @@ potential_constant_expression_1 (tree t, > > tmp = DECL_EXPR_DECL (t); > > if (VAR_P (tmp) && !DECL_ARTIFICIAL (tmp)) > > { > > - if (CP_DECL_THREAD_LOCAL_P (tmp) && !DECL_REALLY_EXTERN (tmp)) > > + if (CP_DECL_THREAD_LOCAL_P (tmp) > > + && !DECL_REALLY_EXTERN (tmp) > > + && (cxx_dialect < cxx20 > > + || (processing_template_decl > > + ? !decl_maybe_constant_var_p (tmp) > > + : !decl_constant_var_p (tmp)))) > > Or here. > > > { > > if (flags & tf_error) > > constexpr_error (DECL_SOURCE_LOCATION (tmp), fundef_p, > > @@ -9596,7 +9602,11 @@ potential_constant_expression_1 (tree t, > > "%<constexpr%> context", tmp); > > return false; > > } > > - else if (TREE_STATIC (tmp)) > > + else if (TREE_STATIC (tmp) > > + && (cxx_dialect < cxx20 > > + || (processing_template_decl > > + ? !decl_maybe_constant_var_p (tmp) > > + : !decl_constant_var_p (tmp)))) > > { > > if (flags & tf_error) > > constexpr_error (DECL_SOURCE_LOCATION (tmp), fundef_p, And these too. > > +static void > > +diagnose_static_in_constexpr (tree decl) > > +{ > > + if (current_function_decl && VAR_P (decl) > > + && DECL_DECLARED_CONSTEXPR_P (current_function_decl) > > + && cxx_dialect < cxx23 > > + && (cxx_dialect < cxx20 > > + || (processing_template_decl > > + ? !decl_maybe_constant_var_p (decl) > > + : !decl_constant_var_p (decl)))) > > For (maybe) constant variables let's make this error a pedwarn in C++20 and > below. Ok. > > > + { > > + bool ok = false; > > + if (CP_DECL_THREAD_LOCAL_P (decl) && !DECL_REALLY_EXTERN (decl)) > > + error_at (DECL_SOURCE_LOCATION (decl), > > + "%qD defined %<thread_local%> in %qs function only " > > + "available with %<-std=c++2b%> or %<-std=gnu++2b%>", decl, > > + DECL_IMMEDIATE_FUNCTION_P (current_function_decl) > > + ? "consteval" : "constexpr"); > > + else if (TREE_STATIC (decl)) > > + error_at (DECL_SOURCE_LOCATION (decl), > > + "%qD defined %<static%> in %qs function only available " > > + "with %<-std=c++2b%> or %<-std=gnu++2b%>", decl, > > + DECL_IMMEDIATE_FUNCTION_P (current_function_decl) > > + ? "consteval" : "constexpr"); > > + else > > + ok = true; > > + if (!ok) > > + cp_function_chain->invalid_constexpr = true; > > + } > > +} > > + > > /* Process a DECLARATOR for a function-scope or namespace-scope > > variable or function declaration. > > (Function definitions go through start_function; class member > > @@ -5860,28 +5895,8 @@ start_decl (const cp_declarator *declara > > DECL_THIS_STATIC (decl) = 1; > > } > > - if (current_function_decl && VAR_P (decl) > > - && DECL_DECLARED_CONSTEXPR_P (current_function_decl) > > - && cxx_dialect < cxx23) > > - { > > - bool ok = false; > > - if (CP_DECL_THREAD_LOCAL_P (decl) && !DECL_REALLY_EXTERN (decl)) > > - error_at (DECL_SOURCE_LOCATION (decl), > > - "%qD defined %<thread_local%> in %qs function only " > > - "available with %<-std=c++2b%> or %<-std=gnu++2b%>", decl, > > - DECL_IMMEDIATE_FUNCTION_P (current_function_decl) > > - ? "consteval" : "constexpr"); > > - else if (TREE_STATIC (decl)) > > - error_at (DECL_SOURCE_LOCATION (decl), > > - "%qD defined %<static%> in %qs function only available " > > - "with %<-std=c++2b%> or %<-std=gnu++2b%>", decl, > > - DECL_IMMEDIATE_FUNCTION_P (current_function_decl) > > - ? "consteval" : "constexpr"); > > - else > > - ok = true; > > - if (!ok) > > - cp_function_chain->invalid_constexpr = true; > > - } > > + if (cxx_dialect < cxx20) > > + diagnose_static_in_constexpr (decl); > > Can we drop this call (and make the ones in cp_finish_decl unconditional)? Yes, will do it. Jakub