From: Jason Merrill <jason@redhat.com>
To: Jakub Jelinek <jakub@redhat.com>
Cc: gcc-patches@gcc.gnu.org
Subject: Re: [PATCH] c++: Implement C++23 P2242R3 - Non-literal variables (and labels and gotos) in constexpr functions
Date: Tue, 5 Oct 2021 17:24:09 -0400 [thread overview]
Message-ID: <10d91c01-590c-1c38-6503-9acbf72d241c@redhat.com> (raw)
In-Reply-To: <20211005123910.GW304296@tucnak>
On 10/5/21 08:39, Jakub Jelinek wrote:
> Hi!
>
> The following patch implements C++23 P2242R3 - Non-literal variables
> (and labels and gotos) in constexpr functions.
> I think it is mostly straightforward, don't diagnose certain
> statements/declarations just because of their presence in
> constexpr/consteval functions, but (except for the non-literal type
> var declarations which ought to be caught by e.g. constructor or
> destructor call during evaluation not being constexpr and for
> labels which are now always allowed) diagnose it during constexpr
> evaluation.
>
> The only unclear thing to me is "a control flow that passes through a
> declaration". The patch implements diagnostics when encountering a
> DECL_EXPR for such variables. But because constexpr/consteval functions
> support switch statements, another thing that can happen is jump over
> such a declaration. Consider e.g. following testcase (not included
> in the patch). When evaluating foo (12) or bar (12) the patch
> accepts those as constant expressions, eventhough it jumps across such
> declarations. For baz (12) and corge (12) it rejects them not
> because of jumping across such declarations, but because those
> static or thread_local variables aren't initialized with constant
> expressions and are accessed. If baz/corge is modified not to have
> const keyword, they are rejected because the vars aren't aren't const.
> If they have const keyword and are initialized by constant expression,
> accesses to those vars are accepted. Is that ok?
That seems correct to me. If they have static initialization, they are
initialized.
Some comments in the patch below.
> So far regtested with
> GXX_TESTSUITE_STDS=98,11,14,17,20,2b make -j32 -k check-g++
> ok for trunk if it passes full bootstrap/regtest?
>
> // { dg-do compile }
> // { dg-options "-std=c++2b" }
>
> int qux ();
>
> constexpr int
> foo (int x)
> {
> switch (x)
> {
> static int bar = qux ();
> case 12:
> return 1;
> }
> return 0;
> }
>
> constexpr int
> bar (int x)
> {
> switch (x)
> {
> thread_local int bar = qux ();
> case 12:
> return 1;
> }
> return 0;
> }
>
> constexpr int
> baz (int x)
> {
> switch (x)
> {
> static const int bar = qux (); // { dg-message "'bar' was not initialized with a constant expression" }
> case 12:
> return bar;
> }
> return 0;
> }
>
> constexpr int
> corge (int x)
> {
> switch (x)
> {
> const thread_local int bar = qux (); // { dg-message "'bar' was not initialized with a constant expression" }
> case 12:
> return bar;
> }
> return 0;
> }
>
> constexpr int a = foo (12);
> constexpr int b = bar (12);
> constexpr int c = baz (12); // { dg-error "the value of 'bar' is not usable in a constant expression" }
> constexpr int d = corge (12); // { dg-error "the value of 'bar' is not usable in a constant expression" }
>
>
> 2021-10-05 Jakub Jelinek <jakub@redhat.com>
>
> gcc/c-family/
> * c-cppbuiltin.c (c_cpp_builtins): For -std=c++23 predefine
> __cpp_constexpr to 202103L rather than 201907L.
> gcc/cp/
> * parser.c (cp_parser_jump_statement): Implement C++23 P2242R3.
> Allow goto expressions in constexpr function bodies for C++23.
> Adjust error message for older standards to mention it.
> * decl.c (start_decl): Allow static and thread_local declarations
> in constexpr function bodies for C++23. Adjust error message for
> older standards to mention it.
> * constexpr.c (ensure_literal_type_for_constexpr_object): Allow
> declarations of variables with non-literal type in constexpr function
> bodies for C++23. Adjust error message for older standards to mention
> it.
> (cxx_eval_constant_expression) <case DECL_EXPR>: Diagnose declarations
> of initialization of static or thread_local vars.
> (cxx_eval_constant_expression) <case GOTO_EXPR>: Diagnose goto
> statements for C++23.
> (potential_constant_expression_1) <case DECL_EXPR>: Allow declarations
> of static and thread_local vars for C++23.
> (potential_constant_expression_1) <case LABEL_EXPR>: Allow labels for
> C++23.
> gcc/testsuite/
> * g++.dg/cpp23/feat-cxx2b.C: Expect __cpp_constexpr 202103L rather
> than 201907L.
> * g++.dg/cpp23/constexpr-nonlit1.C: New test.
> * g++.dg/cpp23/constexpr-nonlit2.C: New test.
> * g++.dg/cpp23/constexpr-nonlit3.C: New test.
> * g++.dg/diagnostic/constexpr1.C: Only expect some diagnostics for
> c++20_down.
> * g++.dg/cpp1y/constexpr-label.C: Likewise.
> * g++.dg/cpp1y/constexpr-neg1.C: Likewise.
> * g++.dg/cpp2a/constexpr-try5.C: Likewise. Adjust some expected
> wording.
> * g++.dg/cpp2a/constexpr-dtor3.C: Likewise.
> * g++.dg/cpp2a/consteval3.C: Likewise. Add effective target c++20
> and remove dg-options.
>
> --- gcc/c-family/c-cppbuiltin.c.jj 2021-09-21 23:31:01.016248936 +0200
> +++ gcc/c-family/c-cppbuiltin.c 2021-10-05 12:54:29.898321379 +0200
> @@ -1052,7 +1052,8 @@ c_cpp_builtins (cpp_reader *pfile)
> cpp_define (pfile, "__cpp_init_captures=201803L");
> cpp_define (pfile, "__cpp_generic_lambdas=201707L");
> cpp_define (pfile, "__cpp_designated_initializers=201707L");
> - cpp_define (pfile, "__cpp_constexpr=201907L");
> + if (cxx_dialect <= cxx20)
> + cpp_define (pfile, "__cpp_constexpr=201907L");
> cpp_define (pfile, "__cpp_constexpr_in_decltype=201711L");
> cpp_define (pfile, "__cpp_conditional_explicit=201806L");
> cpp_define (pfile, "__cpp_consteval=201811L");
> @@ -1071,6 +1072,7 @@ 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=202103L");
> }
> if (flag_concepts)
> {
> --- gcc/cp/parser.c.jj 2021-10-01 18:47:58.090795589 +0200
> +++ gcc/cp/parser.c 2021-10-05 12:54:29.907321254 +0200
> @@ -14176,9 +14176,11 @@ cp_parser_jump_statement (cp_parser* par
>
> case RID_GOTO:
> if (parser->in_function_body
> - && DECL_DECLARED_CONSTEXPR_P (current_function_decl))
> + && DECL_DECLARED_CONSTEXPR_P (current_function_decl)
> + && cxx_dialect < cxx23)
> {
> - error ("%<goto%> in %<constexpr%> function");
> + error ("%<goto%> in %<constexpr%> function only available with "
> + "%<-std=c++2b%> or %<-std=gnu++2b%>");
> cp_function_chain->invalid_constexpr = true;
> }
>
> --- gcc/cp/decl.c.jj 2021-09-21 23:31:01.042248567 +0200
> +++ gcc/cp/decl.c 2021-10-05 12:54:29.909321226 +0200
> @@ -5709,17 +5709,20 @@ start_decl (const cp_declarator *declara
> }
>
> if (current_function_decl && VAR_P (decl)
> - && DECL_DECLARED_CONSTEXPR_P (current_function_decl))
> + && DECL_DECLARED_CONSTEXPR_P (current_function_decl)
> + && cxx_dialect < cxx23)
> {
> bool ok = false;
> if (CP_DECL_THREAD_LOCAL_P (decl))
> error_at (DECL_SOURCE_LOCATION (decl),
> - "%qD declared %<thread_local%> in %qs function", decl,
> + "%qD declared %<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 declared %<static%> in %qs function", decl,
> + "%qD declared %<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
> --- gcc/cp/constexpr.c.jj 2021-09-22 23:19:37.498912776 +0200
> +++ gcc/cp/constexpr.c 2021-10-05 13:56:02.377831320 +0200
> @@ -109,14 +109,15 @@ ensure_literal_type_for_constexpr_object
> explain_non_literal_class (type);
> decl = error_mark_node;
> }
> - else
> + else if (cxx_dialect < cxx23)
> {
> if (!is_instantiation_of_constexpr (current_function_decl))
> {
> auto_diagnostic_group d;
> error_at (DECL_SOURCE_LOCATION (decl),
> - "variable %qD of non-literal type %qT in "
> - "%<constexpr%> function", decl, type);
> + "variable %qD of non-literal type %qT in "
> + "%<constexpr%> function only available with "
> + "%<-std=c++2b%> or %<-std=gnu++2b%>", decl, type);
> explain_non_literal_class (type);
> decl = error_mark_node;
> }
> @@ -6345,6 +6346,26 @@ cxx_eval_constant_expression (const cons
> r = void_node;
> break;
> }
> +
> + if (VAR_P (r)
> + && (TREE_STATIC (r) || CP_DECL_THREAD_LOCAL_P (r))
> + /* Allow __FUNCTION__ etc. */
> + && !DECL_ARTIFICIAL (r))
> + {
> + gcc_assert (cxx_dialect >= cxx23);
> + if (!ctx->quiet)
> + {
> + if (CP_DECL_THREAD_LOCAL_P (r))
> + error_at (loc, "control passes through declaration of %qD "
> + "with thread storage duration", r);
> + else
> + error_at (loc, "control passes through declaration of %qD "
> + "with static storage duration", r);
> + }
> + *non_constant_p = true;
> + break;
> + }
> +
> if (AGGREGATE_TYPE_P (TREE_TYPE (r))
> || VECTOR_TYPE_P (TREE_TYPE (r)))
> {
> @@ -7049,10 +7070,18 @@ cxx_eval_constant_expression (const cons
> break;
>
> case GOTO_EXPR:
> - *jump_target = TREE_OPERAND (t, 0);
> - gcc_assert (breaks (jump_target) || continues (jump_target)
> - /* Allow for jumping to a cdtor_label. */
> - || returns (jump_target));
> + if (breaks (&TREE_OPERAND (t, 0))
> + || continues (&TREE_OPERAND (t, 0))
> + /* Allow for jumping to a cdtor_label. */
> + || returns (&TREE_OPERAND (t, 0)))
> + *jump_target = TREE_OPERAND (t, 0);
> + else
> + {
> + gcc_assert (cxx_dialect >= cxx23);
> + if (!ctx->quiet)
> + error_at (loc, "%<goto%> is not a constant expression");
> + *non_constant_p = true;
> + }
> break;
>
> case LOOP_EXPR:
> @@ -8736,14 +8765,14 @@ potential_constant_expression_1 (tree t,
> tmp = DECL_EXPR_DECL (t);
> if (VAR_P (tmp) && !DECL_ARTIFICIAL (tmp))
> {
> - if (TREE_STATIC (tmp))
> + if (TREE_STATIC (tmp) && cxx_dialect < cxx23)
> {
> if (flags & tf_error)
> error_at (DECL_SOURCE_LOCATION (tmp), "%qD declared "
> "%<static%> in %<constexpr%> context", tmp);
> return false;
> }
> - else if (CP_DECL_THREAD_LOCAL_P (tmp))
> + else if (CP_DECL_THREAD_LOCAL_P (tmp) && cxx_dialect < cxx23)
> {
> if (flags & tf_error)
> error_at (DECL_SOURCE_LOCATION (tmp), "%qD declared "
Hmm, I wouldn't expect this hunk to be needed; if there's a control path
that doesn't include these declarations, we shouldn't hit these errors.
> @@ -9025,7 +9054,7 @@ potential_constant_expression_1 (tree t,
>
> case LABEL_EXPR:
> t = LABEL_EXPR_LABEL (t);
> - if (DECL_ARTIFICIAL (t))
> + if (DECL_ARTIFICIAL (t) || cxx_dialect >= cxx23)
> return true;
> else if (flags & tf_error)
> error_at (loc, "label definition is not a constant expression");
Let's change this message to "only available with..." like the others.
> --- gcc/testsuite/g++.dg/cpp23/feat-cxx2b.C.jj 2021-06-11 23:44:55.883676082 +0200
> +++ gcc/testsuite/g++.dg/cpp23/feat-cxx2b.C 2021-10-05 12:54:29.910321212 +0200
> @@ -134,8 +134,8 @@
>
> #ifndef __cpp_constexpr
> # error "__cpp_constexpr"
> -#elif __cpp_constexpr != 201907
> -# error "__cpp_constexpr != 201907"
> +#elif __cpp_constexpr != 202103
> +# error "__cpp_constexpr != 202103"
> #endif
>
> #ifndef __cpp_decltype_auto
> --- gcc/testsuite/g++.dg/cpp23/constexpr-nonlit1.C.jj 2021-10-05 12:54:29.910321212 +0200
> +++ gcc/testsuite/g++.dg/cpp23/constexpr-nonlit1.C 2021-10-05 13:57:09.582896213 +0200
> @@ -0,0 +1,68 @@
> +// P2242R3
> +// { dg-do compile { target c++14 } }
> +
> +constexpr int
> +foo ()
> +{
> +lab: // { dg-error "label definition is not a constant expression" "" { target c++20_down } }
> + return 1;
> +}
> +
> +constexpr int
> +bar (int x)
> +{
> + if (x)
> + goto lab; // { dg-error "'goto' in 'constexpr' function only available with" "" { target c++20_down } }
> + return 1;
> +lab:
> + return 0;
> +}
> +
> +constexpr int
> +baz (int x)
> +{
> + if (!x)
> + return 1;
> + static int a; // { dg-error "'a' declared 'static' in 'constexpr' function only available with" "" { target c++20_down } }
> + return ++a; // { dg-error "uninitialized variable 'a' in 'constexpr' function" "" { target c++17_down } .-1 }
> +}
> +
> +constexpr int
> +qux (int x)
> +{
> + if (!x)
> + return 1;
> + thread_local int a; // { dg-error "'a' declared 'thread_local' in 'constexpr' function only available with" "" { target c++20_down } }
> + return ++a; // { dg-error "uninitialized variable 'a' in 'constexpr' function" "" { target c++17_down } .-1 }
> +}
> +
> +constexpr int
> +garply (int x)
> +{
> + if (!x)
> + return 1;
> + extern thread_local int a; // { dg-error "'a' declared 'thread_local' in 'constexpr' function only available with" "" { target c++20_down } }
> + return ++a;
> +}
> +
> +struct S { S (); ~S (); int s; }; // { dg-message "'S' is not literal because:" "" { target c++20_down } }
> + // { dg-message "'S' has a non-trivial destructor" "" { target c++17_down } .-1 }
> + // { dg-message "'S' does not have 'constexpr' destructor" "" { target { c++20_only } } .-2 }
> +
> +constexpr int
> +corge (int x)
> +{
> + if (!x)
> + return 1;
> + S s; // { dg-error "variable 's' of non-literal type 'S' in 'constexpr' function only available with" "" { target c++20_down } }
> + return 0;
> +}
> +
> +#if __cpp_constexpr >= 202103L
> +static_assert (foo ());
> +static_assert (bar (0));
> +static_assert (baz (0));
> +static_assert (qux (0));
> +static_assert (garply (0));
> +static_assert (corge (0));
> +#endif
> --- gcc/testsuite/g++.dg/cpp23/constexpr-nonlit2.C.jj 2021-10-05 12:54:29.910321212 +0200
> +++ gcc/testsuite/g++.dg/cpp23/constexpr-nonlit2.C 2021-10-05 12:54:29.910321212 +0200
> @@ -0,0 +1,64 @@
> +// P2242R3
> +// { dg-do compile }
> +// { dg-options "-std=c++2b" }
> +
> +constexpr int
> +foo ()
> +{
> +lab:
> + return 1;
> +}
> +
> +constexpr int
> +bar (int x)
> +{
> + if (x)
> + goto lab; // { dg-error "'goto' is not a constant expression" }
> + return 1;
> +lab:
> + return 0;
> +}
> +
> +constexpr int
> +baz (int x)
> +{
> + if (!x)
> + return 1;
> + static int a; // { dg-error "control passes through declaration of 'a' with static storage duration" }
> + return ++a;
> +}
> +
> +constexpr int
> +qux (int x)
> +{
> + if (!x)
> + return 1;
> + thread_local int a; // { dg-error "control passes through declaration of 'a' with thread storage duration" }
> + return ++a;
> +}
> +
> +constexpr int
> +garply (int x)
> +{
> + if (!x)
> + return 1;
> + thread_local int a; // { dg-error "control passes through declaration of 'a' with thread storage duration" }
> + return ++a;
> +}
> +
> +struct S { S (); ~S (); int s; }; // { dg-message "'S::S\\\(\\\)' declared here" }
> +
> +constexpr int
> +corge (int x)
> +{
> + if (!x)
> + return 1;
> + S s; // { dg-error "call to non-'constexpr' function 'S::S\\\(\\\)'" }
> + return 0;
> +}
> +
> +constexpr int a = bar (1); // { dg-message "in 'constexpr' expansion of" }
> +constexpr int b = baz (1); // { dg-message "in 'constexpr' expansion of" }
> +constexpr int c = qux (1); // { dg-message "in 'constexpr' expansion of" }
> +constexpr int d = garply (1); // { dg-message "in 'constexpr' expansion of" }
> +constexpr int e = corge (1); // { dg-message "in 'constexpr' expansion of" }
> --- gcc/testsuite/g++.dg/cpp23/constexpr-nonlit3.C.jj 2021-10-05 12:54:29.910321212 +0200
> +++ gcc/testsuite/g++.dg/cpp23/constexpr-nonlit3.C 2021-10-05 13:57:21.176734894 +0200
> @@ -0,0 +1,10 @@
> +// P2242R3
> +// { dg-do compile { target c++14 } }
> +
> +constexpr int
> +foo ()
> +{
> + goto lab; // { dg-error "'goto' in 'constexpr' function only available with" "" { target c++20_down } }
> +lab: // { dg-error "'goto' is not a constant expression" "" { target { c++23 } } .-1 }
> + return 1;
> +}
> --- gcc/testsuite/g++.dg/diagnostic/constexpr1.C.jj 2020-01-14 20:02:46.815609354 +0100
> +++ gcc/testsuite/g++.dg/diagnostic/constexpr1.C 2021-10-05 13:56:30.249443508 +0200
> @@ -1,5 +1,5 @@
> // { dg-do compile { target c++11 } }
>
> -constexpr int foo() { thread_local int i __attribute__((unused)) {}; return 1; } // { dg-error "40:.i. declared .thread_local." }
> +constexpr int foo() { thread_local int i __attribute__((unused)) {}; return 1; } // { dg-error "40:.i. declared .thread_local." "" { target c++20_down } }
>
> -constexpr int bar() { static int i __attribute__((unused)) {}; return 1; } // { dg-error "34:.i. declared .static." }
> +constexpr int bar() { static int i __attribute__((unused)) {}; return 1; } // { dg-error "34:.i. declared .static." "" { target c++20_down } }
> --- gcc/testsuite/g++.dg/cpp1y/constexpr-label.C.jj 2020-11-22 23:21:35.866434202 +0100
> +++ gcc/testsuite/g++.dg/cpp1y/constexpr-label.C 2021-10-05 13:37:37.660219970 +0200
> @@ -4,6 +4,6 @@
> constexpr int
> f ()
> {
> -x: // { dg-error "label definition is not a constant expression" }
> +x: // { dg-error "label definition is not a constant expression" "" { target c++20_down } }
> return 42;
> }
> --- gcc/testsuite/g++.dg/cpp1y/constexpr-neg1.C.jj 2020-01-14 20:02:46.773609984 +0100
> +++ gcc/testsuite/g++.dg/cpp1y/constexpr-neg1.C 2021-10-05 13:38:23.322583787 +0200
> @@ -3,13 +3,13 @@
> struct A { A(); };
>
> constexpr int f(int i) {
> - static int j = i; // { dg-error "static" }
> - thread_local int l = i; // { dg-error "thread_local" }
> + static int j = i; // { dg-error "static" "" { target c++20_down } }
> + thread_local int l = i; // { dg-error "thread_local" "" { target c++20_down } }
> goto foo; // { dg-error "goto" }
> foo:
> asm("foo"); // { dg-error "asm" "" { target c++17_down } }
> int k; // { dg-error "uninitialized" "" { target c++17_down } }
> - A a; // { dg-error "non-literal" }
> + A a; // { dg-error "non-literal" "" { target c++20_down } }
> return i;
> }
>
> --- gcc/testsuite/g++.dg/cpp2a/constexpr-try5.C.jj 2020-01-14 20:02:46.000000000 +0100
> +++ gcc/testsuite/g++.dg/cpp2a/constexpr-try5.C 2021-10-05 14:05:21.092057240 +0200
> @@ -5,14 +5,14 @@
> constexpr int foo ()
> try { // { dg-warning "function-try-block body of 'constexpr' function only available with" "" { target c++17_down } }
> int a; // { dg-error "uninitialized variable 'a' in 'constexpr' function" "" { target c++17_down } }
> - static double b = 1.0;// { dg-error "'b' declared 'static' in 'constexpr' function" }
> - goto l; // { dg-error "'goto' in 'constexpr' function" }
> - l:;
> + static double b = 1.0;// { dg-error "'b' declared 'static' in 'constexpr' function only available with" "" { target c++20_down } }
> + goto l; // { dg-error "'goto' in 'constexpr' function only available with" "" { target c++20_down } }
> + l:; // { dg-error "'goto' is not a constant expression" "" { target c++23 } .-1 }
> return 0;
> } catch (...) {
> long int c; // { dg-error "uninitialized variable 'c' in 'constexpr' function" "" { target c++17_down } }
> - static float d = 2.0f;// { dg-error "'d' declared 'static' in 'constexpr' function" }
> - goto l2; // { dg-error "'goto' in 'constexpr' function" }
> + static float d = 2.0f;// { dg-error "'d' declared 'static' in 'constexpr' function only available with" "" { target c++20_down } }
> + goto l2; // { dg-error "'goto' in 'constexpr' function only available with" "" { target c++20_down } }
> l2:;
> return -1;
> }
> @@ -20,20 +20,20 @@ try { // { dg-warning "function-try-bl
> constexpr int bar ()
> {
> int a; // { dg-error "uninitialized variable 'a' in 'constexpr' function" "" { target c++17_down } }
> - static long double b = 3.0;// { dg-error "'b' declared 'static' in 'constexpr' function" }
> - goto l; // { dg-error "'goto' in 'constexpr' function" }
> - l:;
> + static long double b = 3.0;// { dg-error "'b' declared 'static' in 'constexpr' function only available with" "" { target c++20_down } }
> + goto l; // { dg-error "'goto' in 'constexpr' function only available with" "" { target c++20_down } }
> + l:; // { dg-error "'goto' is not a constant expression" "" { target c++23 } .-1 }
> try { // { dg-warning "'try' in 'constexpr' function only available with" "" { target c++17_down } }
> short c; // { dg-error "uninitialized variable 'c' in 'constexpr' function" "" { target c++17_down } }
> - static float d; // { dg-error "'d' declared 'static' in 'constexpr' function" }
> + static float d; // { dg-error "'d' declared 'static' in 'constexpr' function only available with" "" { target c++20_down } }
> // { dg-error "uninitialized variable 'd' in 'constexpr' function" "" { target c++17_down } .-1 }
> - goto l2; // { dg-error "'goto' in 'constexpr' function" }
> + goto l2; // { dg-error "'goto' in 'constexpr' function only available with" "" { target c++20_down } }
> l2:;
> return 0;
> } catch (int) {
> char e; // { dg-error "uninitialized variable 'e' in 'constexpr' function" "" { target c++17_down } }
> - static int f = 5; // { dg-error "'f' declared 'static' in 'constexpr' function" }
> - goto l3; // { dg-error "'goto' in 'constexpr' function" }
> + static int f = 5; // { dg-error "'f' declared 'static' in 'constexpr' function only available with" "" { target c++20_down } }
> + goto l3; // { dg-error "'goto' in 'constexpr' function only available with" "" { target c++20_down } }
> l3:;
> return 1;
> }
> --- gcc/testsuite/g++.dg/cpp2a/constexpr-dtor3.C.jj 2021-04-14 19:19:14.049804260 +0200
> +++ gcc/testsuite/g++.dg/cpp2a/constexpr-dtor3.C 2021-10-05 13:40:48.282564167 +0200
> @@ -180,6 +180,6 @@ f7 ()
> constexpr int
> f8 ()
> {
> - T t4; // { dg-error "variable 't4' of non-literal type 'T' in 'constexpr' function" }
> + T t4; // { dg-error "variable 't4' of non-literal type 'T' in 'constexpr' function only available with" "" { target c++20_down } }
> return 0;
> }
> --- gcc/testsuite/g++.dg/cpp2a/consteval3.C.jj 2020-02-28 23:21:00.540567921 +0100
> +++ gcc/testsuite/g++.dg/cpp2a/consteval3.C 2021-10-05 13:42:17.371322962 +0200
> @@ -1,5 +1,4 @@
> -// { dg-do compile }
> -// { dg-options "-std=c++2a" }
> +// { dg-do compile { target c++20 } }
>
> struct S { S () : a (0), b (1) {} int a, b; };
> int f1 (); // { dg-message "previous declaration 'int f1\\(\\)'" }
> @@ -57,7 +56,7 @@ template consteval float f12 (float x);
> consteval int
> f13 (int x)
> {
> - static int a = 5; // { dg-error "'a' declared 'static' in 'consteval' function" }
> - thread_local int b = 6; // { dg-error "'b' declared 'thread_local' in 'consteval' function" }
> + static int a = 5; // { dg-error "'a' declared 'static' in 'consteval' function only available with" "" { target c++20_only } }
> + thread_local int b = 6; // { dg-error "'b' declared 'thread_local' in 'consteval' function only available with" "" { target c++20_only } }
> return x;
> }
>
> Jakub
>
next prev parent reply other threads:[~2021-10-05 21:24 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-05 12:39 Jakub Jelinek
2021-10-05 21:24 ` Jason Merrill [this message]
2021-10-05 22:24 ` [PATCH, v2] " Jakub Jelinek
2021-10-06 3:01 ` Jason Merrill
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