2022-11-18 Jakub Jelinek gcc/c-family/ * c-cppbuiltin.cc (c_cpp_builtins): Bump __cpp_constexpr value from 202207L to 202211L. gcc/cp/ * constexpr.cc (cxx_eval_constant_expression): Implement C++23 P2647R1 - Permitting static constexpr variables in constexpr functions. Allow DECL_EXPRs of decl_constant_var_p static or thread_local vars. (potential_constant_expression_1): Similarly, except use decl_maybe_constant_var_p instead of decl_constant_var_p if processing_template_decl. * decl.cc (diagnose_static_in_constexpr): New function. (start_decl): Remove diagnostics of static or thread_local vars in constexpr or consteval functions. (cp_finish_decl): Call diagnose_static_in_constexpr. gcc/testsuite/ * g++.dg/cpp23/constexpr-nonlit17.C: New test. * g++.dg/cpp23/constexpr-nonlit18.C: New test. * g++.dg/cpp23/constexpr-nonlit19.C: New test. * g++.dg/cpp23/constexpr-nonlit20.C: New test. * g++.dg/cpp23/feat-cxx2b.C: Adjust expected __cpp_constexpr value. * g++.dg/ext/stmtexpr19.C: Don't expect an error. * g++.dg/ext/stmtexpr25.C: New test. --- gcc/c-family/c-cppbuiltin.cc.jj 2022-11-18 09:00:17.102704379 +0100 +++ gcc/c-family/c-cppbuiltin.cc 2022-11-18 09:32:00.389372850 +0100 @@ -1074,7 +1074,7 @@ c_cpp_builtins (cpp_reader *pfile) /* Set feature test macros for C++23. */ cpp_define (pfile, "__cpp_size_t_suffix=202011L"); cpp_define (pfile, "__cpp_if_consteval=202106L"); - cpp_define (pfile, "__cpp_constexpr=202207L"); + cpp_define (pfile, "__cpp_constexpr=202211L"); cpp_define (pfile, "__cpp_multidimensional_subscript=202211L"); cpp_define (pfile, "__cpp_named_character_escapes=202207L"); cpp_define (pfile, "__cpp_static_call_operator=202207L"); --- gcc/cp/constexpr.cc.jj 2022-11-18 09:00:17.108704295 +0100 +++ gcc/cp/constexpr.cc 2022-11-18 09:35:39.822342414 +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) + && !decl_constant_var_p (r)) { if (!ctx->quiet) { @@ -9586,7 +9587,10 @@ potential_constant_expression_1 (tree t, case DECL_EXPR: tmp = DECL_EXPR_DECL (t); - if (VAR_P (tmp) && !DECL_ARTIFICIAL (tmp)) + if (VAR_P (tmp) && !DECL_ARTIFICIAL (tmp) + && (processing_template_decl + ? !decl_maybe_constant_var_p (tmp) + : !decl_constant_var_p (tmp))) { if (CP_DECL_THREAD_LOCAL_P (tmp) && !DECL_REALLY_EXTERN (tmp)) { --- gcc/cp/decl.cc.jj 2022-11-18 09:03:51.592704514 +0100 +++ gcc/cp/decl.cc 2022-11-18 09:32:00.393372795 +0100 @@ -5600,6 +5600,57 @@ groktypename (cp_decl_specifier_seq *typ return type; } +/* For C++20 and older diagnose static or thread_local decls in constexpr + or consteval functions. If they are usable in constant expressions, + just pedwarn on them. */ + +static void +diagnose_static_in_constexpr (tree decl) +{ + if (cxx_dialect >= cxx23) + return; + if (current_function_decl + && VAR_P (decl) + && DECL_DECLARED_CONSTEXPR_P (current_function_decl)) + { + bool ok = false; + if (processing_template_decl + ? decl_maybe_constant_var_p (decl) + : decl_constant_var_p (decl)) + { + if (CP_DECL_THREAD_LOCAL_P (decl) && !DECL_REALLY_EXTERN (decl)) + pedwarn (DECL_SOURCE_LOCATION (decl), OPT_Wpedantic, + "%qD defined % 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)) + pedwarn (DECL_SOURCE_LOCATION (decl), OPT_Wpedantic, + "%qD defined % in %qs function only available " + "with %<-std=c++2b%> or %<-std=gnu++2b%>", decl, + DECL_IMMEDIATE_FUNCTION_P (current_function_decl) + ? "consteval" : "constexpr"); + ok = true; + } + else if (CP_DECL_THREAD_LOCAL_P (decl) && !DECL_REALLY_EXTERN (decl)) + error_at (DECL_SOURCE_LOCATION (decl), + "%qD defined % 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 % 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 @@ -5860,29 +5911,6 @@ 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 % 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 % 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 (!processing_template_decl && VAR_P (decl)) start_decl_1 (decl, initialized); @@ -8424,6 +8452,9 @@ cp_finish_decl (tree decl, tree init, bo set_user_assembler_name (decl, asmspec); DECL_HARD_REGISTER (decl) = 1; } + + diagnose_static_in_constexpr (decl); + return; } @@ -8749,6 +8780,8 @@ cp_finish_decl (tree decl, tree init, bo && !DECL_HARD_REGISTER (decl)) targetm.lower_local_decl_alignment (decl); + diagnose_static_in_constexpr (decl); + invoke_plugin_callbacks (PLUGIN_FINISH_DECL, decl); } --- gcc/testsuite/g++.dg/cpp23/constexpr-nonlit17.C.jj 2022-11-18 09:32:00.393372795 +0100 +++ gcc/testsuite/g++.dg/cpp23/constexpr-nonlit17.C 2022-11-18 09:32:00.393372795 +0100 @@ -0,0 +1,12 @@ +// P2647R1 - Permitting static constexpr variables in constexpr functions +// { dg-do compile { target c++23 } } + +constexpr char +test () +{ + static const int x = 5; + static constexpr char c[] = "Hello World"; + return *(c + x); +} + +static_assert (test () == ' '); --- gcc/testsuite/g++.dg/cpp23/constexpr-nonlit18.C.jj 2022-11-18 09:32:00.394372781 +0100 +++ gcc/testsuite/g++.dg/cpp23/constexpr-nonlit18.C 2022-11-18 09:32:00.394372781 +0100 @@ -0,0 +1,49 @@ +// P2647R1 - Permitting static constexpr variables in constexpr functions +// { dg-do compile { target c++14 } } + +constexpr int +f1 (int x) +{ + if (x) + throw 1; + return 0; +} + +constexpr int +f2 () +{ + static const int a = f1 (1); // { dg-error "'a' defined 'static' in 'constexpr' function only available with" "" { target c++20_down } } + return 0; +} + +constexpr int +f3 () +{ + static const int a = 5; // { dg-error "'a' defined 'static' in 'constexpr' function only available with" "" { target c++20_down } } + return 0; +} + +constexpr int +f4 () // { dg-message "declared here" "" { target c++20_down } } +{ // { dg-message "is not usable as a 'constexpr' function because:" "" { target c++23 } .-1 } + static const int a = f1 (1); // { dg-error "'a' defined 'static' in 'constexpr' function only available with" "" { target c++20_down } } + return 0; // { dg-error "'a' defined 'static' in 'constexpr' context" "" { target c++23 } .-1 } +} + +constexpr int a4 = f4 (); // { dg-error "called in a constant expression" } + +constexpr int +f5 () +{ + static const int a = f1 (0); // { dg-error "'a' defined 'static' in 'constexpr' function only available with" "" { target c++20_down } } + return 0; +} + +constexpr int +f6 () +{ + static const int a = f1 (0); // { dg-error "'a' defined 'static' in 'constexpr' function only available with" "" { target c++20_down } } + return 0; +} + +constexpr int a6 = f6 (); --- gcc/testsuite/g++.dg/cpp23/constexpr-nonlit19.C.jj 2022-11-18 09:32:00.394372781 +0100 +++ gcc/testsuite/g++.dg/cpp23/constexpr-nonlit19.C 2022-11-18 09:32:00.394372781 +0100 @@ -0,0 +1,50 @@ +// P2647R1 - Permitting static constexpr variables in constexpr functions +// { dg-do compile { target c++14 } } +// { dg-options "-pedantic" } + +constexpr int +f1 (int x) +{ + if (x) + throw 1; + return 0; +} + +constexpr int +f2 () +{ + static const int a = f1 (1); // { dg-error "'a' defined 'static' in 'constexpr' function only available with" "" { target c++20_down } } + return 0; +} + +constexpr int +f3 () +{ + static const int a = 5; // { dg-warning "'a' defined 'static' in 'constexpr' function only available with" "" { target c++20_down } } + return 0; +} + +constexpr int +f4 () // { dg-message "declared here" "" { target c++20_down } } +{ // { dg-message "is not usable as a 'constexpr' function because:" "" { target c++23 } .-1 } + static const int a = f1 (1); // { dg-error "'a' defined 'static' in 'constexpr' function only available with" "" { target c++20_down } } + return 0; // { dg-error "'a' defined 'static' in 'constexpr' context" "" { target c++23 } .-1 } +} + +constexpr int a4 = f4 (); // { dg-error "called in a constant expression" } + +constexpr int +f5 () +{ + static const int a = f1 (0); // { dg-warning "'a' defined 'static' in 'constexpr' function only available with" "" { target c++20_down } } + return 0; +} + +constexpr int +f6 () +{ + static const int a = f1 (0); // { dg-warning "'a' defined 'static' in 'constexpr' function only available with" "" { target c++20_down } } + return 0; +} + +constexpr int a6 = f6 (); --- gcc/testsuite/g++.dg/cpp23/constexpr-nonlit20.C.jj 2022-11-18 09:32:00.394372781 +0100 +++ gcc/testsuite/g++.dg/cpp23/constexpr-nonlit20.C 2022-11-18 09:32:00.394372781 +0100 @@ -0,0 +1,50 @@ +// P2647R1 - Permitting static constexpr variables in constexpr functions +// { dg-do compile { target c++14 } } +// { dg-options "-Wno-pedantic" } + +constexpr int +f1 (int x) +{ + if (x) + throw 1; + return 0; +} + +constexpr int +f2 () +{ + static const int a = f1 (1); // { dg-error "'a' defined 'static' in 'constexpr' function only available with" "" { target c++20_down } } + return 0; +} + +constexpr int +f3 () +{ + static const int a = 5; + return 0; +} + +constexpr int +f4 () // { dg-message "declared here" "" { target c++20_down } } +{ // { dg-message "is not usable as a 'constexpr' function because:" "" { target c++23 } .-1 } + static const int a = f1 (1); // { dg-error "'a' defined 'static' in 'constexpr' function only available with" "" { target c++20_down } } + return 0; // { dg-error "'a' defined 'static' in 'constexpr' context" "" { target c++23 } .-1 } +} + +constexpr int a4 = f4 (); // { dg-error "called in a constant expression" } + +constexpr int +f5 () +{ + static const int a = f1 (0); + return 0; +} + +constexpr int +f6 () +{ + static const int a = f1 (0); + return 0; +} + +constexpr int a6 = f6 (); --- gcc/testsuite/g++.dg/cpp23/feat-cxx2b.C.jj 2022-11-18 09:00:17.293701708 +0100 +++ gcc/testsuite/g++.dg/cpp23/feat-cxx2b.C 2022-11-18 09:32:00.394372781 +0100 @@ -134,8 +134,8 @@ #ifndef __cpp_constexpr # error "__cpp_constexpr" -#elif __cpp_constexpr != 202207 -# error "__cpp_constexpr != 202207" +#elif __cpp_constexpr != 202211 +# error "__cpp_constexpr != 202211" #endif #ifndef __cpp_decltype_auto --- gcc/testsuite/g++.dg/ext/stmtexpr19.C.jj 2022-11-18 09:00:17.367700673 +0100 +++ gcc/testsuite/g++.dg/ext/stmtexpr19.C 2022-11-18 09:43:20.682975254 +0100 @@ -8,7 +8,7 @@ const test* setup() { static constexpr test atest = { - ({ static const int inner = 123; &inner; }) // { dg-error "static" } + ({ static const int inner = 123; &inner; }) }; return &atest; --- gcc/testsuite/g++.dg/ext/stmtexpr25.C.jj 2022-11-18 09:43:08.505143556 +0100 +++ gcc/testsuite/g++.dg/ext/stmtexpr25.C 2022-11-18 09:44:39.672883560 +0100 @@ -0,0 +1,17 @@ +// PR c++/81073 +// { dg-options "" } +// { dg-do compile { target c++11 } } + +struct test { const int *addr; }; + +const test* setup() +{ + static constexpr test atest = + { + ({ static const int inner = (throw 1, 1); &inner; }) // { dg-error "static" "" } + }; + + return &atest; +} + +int main(){}