On 10/19/21 09:24, Jakub Jelinek wrote:
On Tue, Oct 19, 2021 at 02:00:21PM +0200, Jakub Jelinek via Gcc-patches wrote:And another thing isn't in a patch, but I'm wondering whether we don't handle it incorrectly. constexpr.c has: /* Check that immediate invocation does not return an expression referencing any immediate function decls. They need to be allowed while parsing immediate functions, but can't leak outside of them. */ if (is_consteval && t != r && (current_function_decl == NULL_TREE || !DECL_IMMEDIATE_FUNCTION_P (current_function_decl))) as condition for the discovery of embedded immediate FUNCTION_DECLs (or now PTRMEM_CSTs). If I remove the && (current... ..._decl)) then g++.dg/cpp2a/consteval7.C's struct S { int b; int (*c) (); }; consteval S baz () { return { 5, foo }; } consteval int qux () { S s = baz (); return s.b + s.c (); } consteval int quux () { constexpr S s = baz (); return s.b + s.c (); } quux line fails, but based on http://eel.is/c++draft/expr.const#11 I wonder if it shouldn't fail (clang++ -std=c++20 rejects it), and be only accepted without the constexpr keyword before S s.Here is an incremental patch that implements that.
OK.
2021-10-19 Jakub Jelinek <ja...@redhat.com> PR c++/102753 * constexpr.c (cxx_eval_outermost_constant_expr): Perform find_immediate_fndecl discovery if is_consteval or in_immediate_context () rather than if is_consteval, t != r and not in immediate function's body. * g++.dg/cpp2a/consteval7.C: Expect diagnostics on quux. * g++.dg/cpp2a/consteval24.C: New test. * g++.dg/cpp23/consteval-if12.C: New test. --- gcc/cp/constexpr.c.jj 2021-10-19 12:22:35.583964001 +0200 +++ gcc/cp/constexpr.c 2021-10-19 13:58:22.545182032 +0200 @@ -7472,12 +7472,8 @@ cxx_eval_outermost_constant_expr (tree t }/* Check that immediate invocation does not return an expression referencing- any immediate function decls. They need to be allowed while parsing - immediate functions, but can't leak outside of them. */ - if (is_consteval - && t != r - && (current_function_decl == NULL_TREE - || !DECL_IMMEDIATE_FUNCTION_P (current_function_decl))) + any immediate function decls. */ + if (is_consteval || in_immediate_context ()) if (tree immediate_fndecl = cp_walk_tree_without_duplicates (&r, find_immediate_fndecl, NULL)) --- gcc/testsuite/g++.dg/cpp2a/consteval7.C.jj 2020-01-12 11:54:37.140402440 +0100 +++ gcc/testsuite/g++.dg/cpp2a/consteval7.C 2021-10-19 13:59:54.033897061 +0200 @@ -7,7 +7,7 @@ constexpr auto a = bar (); // { dg-error struct S { int b; int (*c) (); }; consteval S baz () { return { 5, foo }; } consteval int qux () { S s = baz (); return s.b + s.c (); } -consteval int quux () { constexpr S s = baz (); return s.b + s.c (); } +consteval int quux () { constexpr S s = baz (); return s.b + s.c (); } // { dg-error "immediate evaluation returns address of immediate function 'consteval int foo\\(\\)'" } constexpr auto d = baz (); // { dg-error "immediate evaluation returns address of immediate function 'consteval int foo\\(\\)'" } constexpr auto e = qux (); constexpr auto f = quux (); --- gcc/testsuite/g++.dg/cpp2a/consteval24.C.jj 2021-10-19 14:32:51.858019368 +0200 +++ gcc/testsuite/g++.dg/cpp2a/consteval24.C 2021-10-19 14:49:11.618177303 +0200 @@ -0,0 +1,30 @@ +// PR c++/102753 +// { dg-do compile { target c++20 } } + +struct S { + constexpr S () : s (0) {} + consteval int foo () { return 1; } + virtual consteval int bar () { return 2; } + int s; +}; + +consteval int foo () { return 42; } +consteval auto baz () { return foo; } +consteval auto qux () { return &S::foo; } +consteval auto corge () { return &S::bar; } + +consteval int +bar () +{ + S s; + constexpr auto fn1 = foo; // { dg-error "immediate evaluation returns address of immediate function" } + constexpr auto fn2 = &foo; // { dg-error "immediate evaluation returns address of immediate function" } + constexpr auto fn3 = &S::foo; // { dg-error "immediate evaluation returns address of immediate function" } + constexpr auto fn4 = &S::bar; // { dg-error "immediate evaluation returns address of immediate function" } + constexpr auto fn5 = baz (); // { dg-error "immediate evaluation returns address of immediate function" } + constexpr auto fn6 = qux (); // { dg-error "immediate evaluation returns address of immediate function" } + constexpr auto fn7 = corge (); // { dg-error "immediate evaluation returns address of immediate function" } + return fn1 () + fn2 () + (s.*fn3) () + (s.*fn4) () + fn5 () + (s.*fn6) () + (s.*fn7) (); +} + +auto a = bar (); --- gcc/testsuite/g++.dg/cpp23/consteval-if12.C.jj 2021-10-19 14:54:05.123023731 +0200 +++ gcc/testsuite/g++.dg/cpp23/consteval-if12.C 2021-10-19 14:55:29.026844039 +0200 @@ -0,0 +1,34 @@ +// PR c++/102753 +// { dg-do compile { target c++20 } } +// { dg-options "" } + +struct S { + constexpr S () : s (0) {} + consteval int foo () { return 1; } + virtual consteval int bar () { return 2; } + int s; +}; + +consteval int foo () { return 42; } +consteval auto baz () { return foo; } +consteval auto qux () { return &S::foo; } +consteval auto corge () { return &S::bar; } + +constexpr int +bar () +{ + S s; + if consteval { // { dg-warning "'if consteval' only available with" "" { target c++20_only } } + constexpr auto fn1 = foo; // { dg-error "immediate evaluation returns address of immediate function" } + constexpr auto fn2 = &foo; // { dg-error "immediate evaluation returns address of immediate function" } + constexpr auto fn3 = &S::foo; // { dg-error "immediate evaluation returns address of immediate function" } + constexpr auto fn4 = &S::bar; // { dg-error "immediate evaluation returns address of immediate function" } + constexpr auto fn5 = baz (); // { dg-error "immediate evaluation returns address of immediate function" } + constexpr auto fn6 = qux (); // { dg-error "immediate evaluation returns address of immediate function" } + constexpr auto fn7 = corge (); // { dg-error "immediate evaluation returns address of immediate function" } + return fn1 () + fn2 () + (s.*fn3) () + (s.*fn4) () + fn5 () + (s.*fn6) () + (s.*fn7) (); + } + return 0; +} + +auto a = bar (); Jakub
