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c++: mangle function template constraints

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Per https://github.com/itanium-cxx-abi/cxx-abi/issues/24 and
https://github.com/itanium-cxx-abi/cxx-abi/pull/166

We need to mangle constraints to be able to distinguish between function
templates that only differ in constraints.  From the latter link, we want to
use the template parameter mangling previously specified for lambdas to also
make explicit the form of a template parameter where the argument is not a
"natural" fit for it, such as when the parameter is constrained or deduced.

I'm concerned about how the latter link changes the mangling for some C++98
and C++11 patterns, so I've limited template_parm_natural_p to avoid two
cases found by running the testsuite with -Wabi forced on:

template <class T, T V> T f() { return V; }
int main() { return f<int,42>(); }

template <int i> int max() { return i; }
template <int i, int j, int... rest> int max()
{
  int sub = max<j, rest...>();
  return i > sub ? i : sub;
}
int main() {  return max<1,2,3>(); }

A third C++11 pattern is changed by this patch:

template <template <typename...> class TT, typename... Ts> TT<Ts...> f();
template <typename> struct A { };
int main() { f<A,int>(); }

I aim to resolve these with the ABI committee before GCC 14.1.

We also need to resolve https://github.com/itanium-cxx-abi/cxx-abi/issues/38
(mangling references to dependent template-ids where the name is fully
resolved) as references to concepts in std:: will consistently run into this
area.  This is why mangle-concepts1.C only refers to concepts in the global
namespace so far.

The library changes are to avoid trying to mangle builtins, which fails.

Demangler support and test coverage is not complete yet.

gcc/cp/ChangeLog:

	* cp-tree.h (TEMPLATE_ARGS_TYPE_CONSTRAINT_P): New.
	(get_concept_check_template): Declare.
	* constraint.cc (combine_constraint_expressions)
	(finish_shorthand_constraint): Use UNKNOWN_LOCATION.
	* pt.cc (convert_generic_types_to_packs): Likewise.
	* mangle.cc (write_constraint_expression)
	(write_tparms_constraints, write_type_constraint)
	(template_parm_natural_p, write_requirement)
	(write_requires_expr): New.
	(write_encoding): Mangle trailing requires-clause.
	(write_name): Pass parms to write_template_args.
	(write_template_param_decl): Factor out from...
	(write_closure_template_head): ...here.
	(write_template_args): Mangle non-natural parms
	and requires-clause.
	(write_expression): Handle REQUIRES_EXPR.

include/ChangeLog:

	* demangle.h (enum demangle_component_type): Add
	DEMANGLE_COMPONENT_CONSTRAINTS.

libiberty/ChangeLog:

	* cp-demangle.c (d_make_comp): Handle
	DEMANGLE_COMPONENT_CONSTRAINTS.
	(d_count_templates_scopes): Likewise.
	(d_print_comp_inner): Likewise.
	(d_maybe_constraints): New.
	(d_encoding, d_template_args_1): Call it.
	(d_parmlist): Handle 'Q'.
	* testsuite/demangle-expected: Add some constraint tests.

libstdc++-v3/ChangeLog:

	* include/std/bit: Avoid builtins in requires-clauses.
	* include/std/variant: Likewise.

gcc/testsuite/ChangeLog:

	* g++.dg/abi/mangle10.C: Disable compat aliases.
	* g++.dg/abi/mangle52.C: Specify ABI 18.
	* g++.dg/cpp2a/class-deduction-alias3.C
	* g++.dg/cpp2a/class-deduction-alias8.C:
	Avoid builtins in requires-clauses.
	* g++.dg/abi/mangle-concepts1.C: New test.
	* g++.dg/abi/mangle-ttp1.C: New test.
This commit is contained in:
Jason Merrill 2023-09-25 10:15:02 +01:00
parent c6bb413eeb
commit c3f281a0c1
15 changed files with 550 additions and 71 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
gcc/cp/constraint.cc
View File

@ -240,7 +240,9 @@ combine_constraint_expressions (tree lhs, tree rhs)
return rhs;
if (!rhs)
return lhs;
return finish_constraint_and_expr (input_location, lhs, rhs);
/* Use UNKNOWN_LOCATION so write_template_args can tell the difference
between this and a && the user wrote. */
return finish_constraint_and_expr (UNKNOWN_LOCATION, lhs, rhs);
}
/* Extract the template-id from a concept check. For standard and variable
@ -1605,9 +1607,11 @@ finish_shorthand_constraint (tree decl, tree constr)
check = ovl_make (tmpl);
check = build_concept_check (check, arg, args, tf_warning_or_error);
/* Make the check a fold-expression if needed. */
/* Make the check a fold-expression if needed.
Use UNKNOWN_LOCATION so write_template_args can tell the
difference between this and a fold the user wrote. */
if (apply_to_each_p && declared_pack_p)
check = finish_left_unary_fold_expr (DECL_SOURCE_LOCATION (decl),
check = finish_left_unary_fold_expr (UNKNOWN_LOCATION,
check, TRUTH_ANDIF_EXPR);
return check;

7
gcc/cp/cp-tree.h
View File

@ -3799,6 +3799,12 @@ struct GTY(()) lang_decl {
: TREE_VEC_LENGTH (INNERMOST_TEMPLATE_ARGS (NODE))
#endif
/* True iff NODE represents the template args for a type-constraint,
in which case the first one represents the constrained type.
Currently only set during mangling. */
#define TEMPLATE_ARGS_TYPE_CONSTRAINT_P(NODE) \
TREE_PRIVATE (TREE_VEC_CHECK (NODE))
/* The list of access checks that were deferred during parsing
which need to be performed at template instantiation time.
@ -8509,6 +8515,7 @@ struct processing_constraint_expression_sentinel
extern bool processing_constraint_expression_p ();
extern tree unpack_concept_check (tree);
extern tree get_concept_check_template (tree);
extern tree evaluate_concept_check (tree);
extern bool constraints_satisfied_p (tree, tree = NULL_TREE);
extern bool* lookup_subsumption_result (tree, tree);

369
gcc/cp/mangle.cc
View File

@ -221,7 +221,7 @@ static void write_function_type (const tree);
static void write_bare_function_type (const tree, const int, const tree);
static void write_method_parms (tree, const int, const tree);
static void write_class_enum_type (const tree);
static void write_template_args (tree);
static void write_template_args (tree, tree = NULL_TREE);
static void write_expression (tree);
static void write_template_arg_literal (const tree);
static void write_template_arg (tree);
@ -842,6 +842,70 @@ mangle_return_type_p (tree decl)
&& maybe_template_info (decl));
}
/* <constraint-expression> ::= <expression> */
static void
write_constraint_expression (tree expr)
{
write_expression (expr);
}
/* Mangle a requires-clause following a template-head, if any.
Q <constraint_expression> E */
static void
write_tparms_constraints (tree constraints)
{
/* In a declaration with shorthand constraints in the template-head, followed
by a requires-clause, followed by shorthand constraints in the
function-parameter-list, the full constraints will be some && with the
parameter constraints on the RHS, around an && with the requires-clause on
the RHS. Find the requires-clause, if any.
This logic relies on the && and ... from combine_constraint_expressions,
finish_shorthand_constraint, and convert_generic_types_to_packs having
UNKNOWN_LOCATION. If they need to have an actual location, we could move
to using a TREE_LANG_FLAG. */
if (constraints && abi_check (19))
{
tree probe = constraints;
while (probe
&& !EXPR_LOCATION (probe)
&& TREE_CODE (probe) == TRUTH_ANDIF_EXPR)
{
tree op1 = TREE_OPERAND (probe, 1);
probe = (EXPR_LOCATION (op1) ? op1
: TREE_OPERAND (probe, 0));
}
if (probe && EXPR_LOCATION (probe))
{
write_char ('Q');
write_constraint_expression (probe);
}
}
}
/* <type-constraint> ::= <name> */
static void
write_type_constraint (tree cnst)
{
if (!cnst) return;
cnst = unpack_concept_check (cnst);
gcc_checking_assert (TREE_CODE (cnst) == TEMPLATE_ID_EXPR);
tree concept_decl = get_concept_check_template (cnst);
write_name (concept_decl, 0);
tree args = TREE_OPERAND (cnst, 1);
if (TREE_VEC_LENGTH (args) > 1)
{
TEMPLATE_ARGS_TYPE_CONSTRAINT_P (args) = true;
write_template_args (args);
}
}
/* <encoding> ::= <function name> <bare-function-type>
::= <data name> */
@ -886,6 +950,14 @@ write_encoding (const tree decl)
mangle_return_type_p (decl),
d);
if (tree c = get_trailing_function_requirements (decl))
if (abi_check (19))
{
++G.parm_depth;
write_char ('Q');
write_constraint_expression (c);
--G.parm_depth;
}
}
}
@ -1037,7 +1109,13 @@ write_name (tree decl, const int ignore_local_scope)
{
/* Yes: use <unscoped-template-name>. */
write_unscoped_template_name (TI_TEMPLATE (info));
write_template_args (TI_ARGS (info));
/* Pass down the parms of a function template in case we need to
mangle them; we don't mangle the parms of a non-overloadable
template. */
tree parms = (TREE_CODE (decl) == FUNCTION_DECL
? DECL_TEMPLATE_PARMS (TI_TEMPLATE (info))
: NULL_TREE);
write_template_args (TI_ARGS (info), parms);
}
else
/* Everything else gets an <unqualified-name>. */
@ -1722,10 +1800,136 @@ write_unnamed_type_name (const tree type)
write_compact_number (discriminator);
}
/* ABI issue #47: if a function template parameter is not "natural" for its
argument we must mangle the parameter. */
static bool
template_parm_natural_p (tree arg, tree parm)
{
tree decl = TREE_VALUE (parm);
/* A template parameter is "natural" if: */
if (template_parameter_pack_p (decl))
{
tree args = ARGUMENT_PACK_ARGS (arg);
if (TREE_VEC_LENGTH (args) == 0)
{
#if 0
/* the argument is an empty pack and the parameter is an
unconstrained template type parameter pack; */
if (TREE_CODE (decl) != TYPE_DECL)
return false;
#else
/* Defer changing the mangling of C++11 code like
template <int i> int max();
template <int i, int j, int... rest> int max(); */
return true;
#endif
}
else
/* the argument is a non-empty pack and a non-pack variant of the
parameter would be natural for the first element of the pack; */
arg = TREE_VEC_ELT (args, 0);
}
/* the argument is a template and the parameter has the exact
same template head; */
if (TREE_CODE (decl) == TEMPLATE_DECL)
return template_heads_equivalent_p (arg, decl);
/* the argument is a type and the parameter is unconstrained; or */
else if (TREE_CODE (decl) == TYPE_DECL)
return !TEMPLATE_PARM_CONSTRAINTS (parm);
/* the argument is a non-type template argument and the declared parameter
type neither is instantiation dependent nor contains deduced types. */
else if (TREE_CODE (decl) == PARM_DECL)
{
#if 0
return !uses_template_parms (TREE_TYPE (decl));
#else
/* Defer changing the mangling of C++98 code like
template <class T, T V> .... */
return !type_uses_auto (TREE_TYPE (decl));
#endif
}
gcc_unreachable ();
}
/* Used for lambda template head and non-natural function template parameters.
<template-param-decl> ::= Ty # template type parameter
::= Tk <type-constraint> # constrained type parameter
::= Tn <type> # template non-type parameter
::= Tt <template-param-decl>* [Q <constraint-expression] E # ttp
::= Tp <non-pack template-param-decl> # template parameter pack */
static void
write_template_param_decl (tree parm)
{
tree decl = TREE_VALUE (parm);
if (template_parameter_pack_p (decl))
write_string ("Tp");
switch (TREE_CODE (decl))
{
case PARM_DECL:
{
write_string ("Tn");
tree type = TREE_TYPE (decl);
if (tree c = (is_auto (type)
? PLACEHOLDER_TYPE_CONSTRAINTS (type)
: NULL_TREE))
{
if (AUTO_IS_DECLTYPE (type))
write_string ("DK");
else
write_string ("Dk");
write_type_constraint (c);
}
else
write_type (type);
}
break;
case TEMPLATE_DECL:
{
write_string ("Tt");
tree parms = DECL_INNERMOST_TEMPLATE_PARMS (decl);
for (tree node : tree_vec_range (parms))
write_template_param_decl (node);
write_char ('E');
}
break;
case TYPE_DECL:
if (tree c = TEMPLATE_PARM_CONSTRAINTS (parm))
{
if (TREE_CODE (c) == UNARY_LEFT_FOLD_EXPR)
{
c = FOLD_EXPR_PACK (c);
c = PACK_EXPANSION_PATTERN (c);
}
if (TREE_CODE (decl) == TYPE_DECL)
{
write_string ("Tk");
write_type_constraint (c);
}
}
else
write_string ("Ty");
break;
default:
gcc_unreachable ();
}
}
// A template head, for templated lambdas.
// <template-head> ::= Tp* Ty
// Tp* Tn <type>
// Tp* Tt <template-head> E
// New in ABI=18. Returns true iff we emitted anything -- used for ABI
// version warning.
@ -1735,50 +1939,26 @@ write_closure_template_head (tree tmpl)
bool any = false;
// We only need one level of template parms
tree inner = INNERMOST_TEMPLATE_PARMS (DECL_TEMPLATE_PARMS (tmpl));
tree parms = DECL_TEMPLATE_PARMS (tmpl);
tree inner = INNERMOST_TEMPLATE_PARMS (parms);
for (int ix = 0, len = TREE_VEC_LENGTH (inner); ix != len; ix++)
{
tree parm = TREE_VEC_ELT (inner, ix);
if (parm == error_mark_node)
continue;
parm = TREE_VALUE (parm);
if (DECL_IMPLICIT_TEMPLATE_PARM_P (parm))
if (DECL_IMPLICIT_TEMPLATE_PARM_P (TREE_VALUE (parm)))
// A synthetic parm, we're done.
break;
any = true;
if (abi_version_at_least (18))
{
if (TREE_CODE (parm) == PARM_DECL
? TEMPLATE_PARM_PARAMETER_PACK (DECL_INITIAL (parm))
: TEMPLATE_TYPE_PARAMETER_PACK (TREE_TYPE (parm)))
write_string ("Tp");
switch (TREE_CODE (parm))
{
default:
gcc_unreachable ();
case TYPE_DECL:
write_string ("Ty");
break;
case PARM_DECL:
write_string ("Tn");
write_type (TREE_TYPE (parm));
break;
case TEMPLATE_DECL:
write_string ("Tt");
write_closure_template_head (parm);
write_string ("E");
break;
}
}
write_template_param_decl (parm);
}
write_tparms_constraints (TEMPLATE_PARMS_CONSTRAINTS (parms));
return any;
}
@ -2893,13 +3073,84 @@ write_class_enum_type (const tree type)
write_name (TYPE_NAME (type), /*ignore_local_scope=*/0);
}
/* Mangle a requirement REQ in a requires-expression. */
static void
write_requirement (tree req)
{
tree op = TREE_OPERAND (req, 0);
switch (tree_code code = TREE_CODE (req))
{
/* # simple-requirement or compound-requirement
<requirement> ::= X <expression> [ N ] [ R <type-constraint> ] */
case SIMPLE_REQ:
case COMPOUND_REQ:
write_char ('X');
write_expression (op);
if (code == SIMPLE_REQ)
break;
if (COMPOUND_REQ_NOEXCEPT_P (req))
write_char ('N');
if (tree constr = TREE_OPERAND (req, 1))
{
write_char ('R');
write_type_constraint (PLACEHOLDER_TYPE_CONSTRAINTS (constr));
}
break;
/* <requirement> ::= T <type> # type-requirement */
case TYPE_REQ:
write_char ('T');
write_type (op);
break;
/* <requirement> ::= Q <constraint-expression> # nested-requirement */
case NESTED_REQ:
write_char ('Q');
write_constraint_expression (op);
break;
default:
gcc_unreachable ();
}
}
/* # requires { ... }
<expression> ::= rq <requirement>+ E
# requires (...) { ... }
<expression> ::= rQ <bare-function-type> _ <requirement>+ E */
static void
write_requires_expr (tree expr)
{
tree parms = REQUIRES_EXPR_PARMS (expr);
if (parms)
{
write_string ("rQ");
++G.parm_depth;
for (; parms; parms = DECL_CHAIN (parms))
write_type (cv_unqualified (TREE_TYPE (parms)));
--G.parm_depth;
write_char ('_');
}
else
write_string ("rq");
for (tree reqs = REQUIRES_EXPR_REQS (expr); reqs;
reqs = TREE_CHAIN (reqs))
write_requirement (TREE_VALUE (reqs));
write_char ('E');
}
/* Non-terminal <template-args>. ARGS is a TREE_VEC of template
arguments.
<template-args> ::= I <template-arg>* E */
<template-args> ::= I <template-arg>* [Q <constraint-expr>] E */
static void
write_template_args (tree args)
write_template_args (tree args, tree parms /*= NULL_TREE*/)
{
int i;
int length = 0;
@ -2911,6 +3162,13 @@ write_template_args (tree args)
if (args)
length = TREE_VEC_LENGTH (args);
tree constraints = NULL_TREE;
if (parms)
{
constraints = TEMPLATE_PARMS_CONSTRAINTS (parms);
parms = INNERMOST_TEMPLATE_PARMS (parms);
}
if (args && length && TREE_CODE (TREE_VEC_ELT (args, 0)) == TREE_VEC)
{
/* We have nested template args. We want the innermost template
@ -2918,8 +3176,38 @@ write_template_args (tree args)
args = TREE_VEC_ELT (args, length - 1);
length = TREE_VEC_LENGTH (args);
}
for (i = 0; i < length; ++i)
write_template_arg (TREE_VEC_ELT (args, i));
if (TEMPLATE_ARGS_TYPE_CONSTRAINT_P (args))
/* Skip the constrained type. */
i = 1;
else
i = 0;
bool implicit_parm_scope = false;
for (; i < length; ++i)
{
tree arg = TREE_VEC_ELT (args, i);
if (parms)
{
tree parm = TREE_VEC_ELT (parms, i);
tree decl = TREE_VALUE (parm);
if (DECL_IMPLICIT_TEMPLATE_PARM_P (decl)
&& !implicit_parm_scope)
{
/* The rest of the template parameters are based on generic
function parameters, so any expressions in their
type-constraints are in parameter scope. */
implicit_parm_scope = true;
++G.parm_depth;
}
if (!template_parm_natural_p (arg, parm)
&& abi_check (19))
write_template_param_decl (parm);
}
write_template_arg (arg);
}
if (implicit_parm_scope)
--G.parm_depth;
write_tparms_constraints (constraints);
write_char ('E');
}
@ -3107,6 +3395,7 @@ write_expression (tree expr)
write_char ('f');
if (delta != 0)
{
gcc_checking_assert (delta > 0);
if (abi_check (5))
{
/* Let L be the number of function prototype scopes from the
@ -3431,6 +3720,8 @@ write_expression (tree expr)
write_type (LAMBDA_EXPR_CLOSURE (expr));
write_char ('E');
}
else if (code == REQUIRES_EXPR)
write_requires_expr (expr);
else if (dependent_name (expr))
{
tree name = dependent_name (expr);

4
gcc/cp/pt.cc
View File

@ -30951,7 +30951,9 @@ convert_generic_types_to_packs (tree parm, int start_idx, int end_idx)
{
tree id = unpack_concept_check (constr);
TREE_VEC_ELT (TREE_OPERAND (id, 1), 0) = t;
location_t loc = DECL_SOURCE_LOCATION (TYPE_NAME (t));
/* Use UNKNOWN_LOCATION so write_template_args can tell the
difference between this and a fold the user wrote. */
location_t loc = UNKNOWN_LOCATION;
tree fold = finish_left_unary_fold_expr (loc, constr,
TRUTH_ANDIF_EXPR);
TEMPLATE_PARM_CONSTRAINTS (node) = fold;

88
gcc/testsuite/g++.dg/abi/mangle-concepts1.C Normal file
View File

@ -0,0 +1,88 @@
// { dg-do compile { target c++20 } }
template <class T> concept C = true;
template <class T, class U> concept C2 = true;
template <class T> concept D = true;
template <class T> concept E = true;
template <class T> concept F = true;
template <class T> using Ref = T&;
// { dg-final { scan-assembler "_Z1fIiQ1CIT_EEvv" } }
template <class T> requires C<T> void f() {}
template void f<int>();
// { dg-final { scan-assembler "_Z2f2ITk1CiEvv" } }
template <C T> void f2() {}
template void f2<int>();
// { dg-final { scan-assembler "_Z2f3IiEvvQ1CIT_E" } }
template <class T> void f3() requires C<T> {}
template void f3<int>();
// { dg-final { scan-assembler "_Z2f4ITk1CiEvT_" } }
void f4(C auto c) {}
template void f4(int);
// ??? The constraints end up out of order in the mangled name, may
// need to change the equivalence rule.
// { dg-final { scan-assembler "_Z2f5ITk1CicTk1EfTk1FsQ1DIT0_EEvT1_T2_" } }
template <C T, class U> requires D<U> void f5(E auto c, F auto f) {}
template void f5<int,char>(float,short);
// { dg-final { scan-assembler "_Z2f6ITk2C2IiEsEvv" } }
template <C2<int> T> void f6() {}
template void f6<short>();
// { dg-final { scan-assembler "_ZN1AIiE1fEvQ1CIT_E" } }
template <class T> struct A {
void f() requires C<T> { };
};
template struct A<int>;
// { dg-final { scan-assembler "_Z1gIiQrqXcvT__ETRS0_Q1CIS0_EXpscvS0__ENR1CEEvv" } }
template <class T>
requires requires { T();
typename Ref<T>;
requires C<T>;
{ +T() } noexcept -> C;
}
void g() {}
template void g<int>();
// { dg-final { scan-assembler "_Z1hIiQrQT__Xpsfp_EEvv" } }
template <class T>
requires requires (T t) { +t; }
void h() {}
template void h<int>();
// { dg-final { scan-assembler "_Z3fn1IiEvT_QrQS0__XpsfL0p_Xpsfp_E" } }
template <class T>
void fn1(T t1)
requires requires (T t2) { +t1; +t2; }
{}
template void fn1<int>(int);
// { dg-final { scan-assembler "_Z3fn3IiTk2C2IDtfL0p_EEiEvT_T0_" } }
template<typename T> void fn3(T t, C2<decltype(t)> auto) {}
template void fn3(int, int);
// { dg-final { scan-assembler "_Z3fn4IiiEvT_T0_Q2C2IS1_FDTcl3fn3fL0p_fp_EES0_EE" } }
template<typename T, typename U> void fn4(T t, U u)
requires C2<U, auto (T u) -> decltype(fn3(t, u))> {}
template void fn4(int, int);
// { dg-final { scan-assembler "_Z3fn5ITpTk1CJicfEEvDpT_" } }
template<C... T> void fn5(T...) { }
template void fn5(int,char,float);
// { dg-final { scan-assembler "_ZN2A2IiE1BIiE1fIiiEEvvQ2C2IT_TL1_0_E" } }
template <class T> struct A2 {
template <class X> struct B {
template <class U, class V> void f() requires C2<T,V> {}
};
};
template void A2<int>::B<int>::f<int,int>();
template<C auto N> void f7() {}
// { dg-final { scan-assembler "_Z2f7ITnDk1CLi5EEvv" } }
template void f7<5>();

27
gcc/testsuite/g++.dg/abi/mangle-ttp1.C Normal file
View File

@ -0,0 +1,27 @@
// ABI #47 "natural" template parameter mangling
// { dg-do compile { target c++17 } }
template <template <class...> class TT> class A { };
template <int... T> class B { };
template <auto... T>
void f(B<T...> b);
template <template <auto...> class TT>
void g(TT<42>);
template <template <int...> class TT>
void h(TT<42>);
template <class T> struct C {
template <template <T...> class TT> static void j(TT<42>);
};
int main()
{
B<42> b;
f(b); // { dg-final { scan-assembler "_Z1fITpTnDaJLi42EEEv1BIJXspT_EEE" } }
g(b); // { dg-final { scan-assembler "_Z1gITtTpTnDaE1BEvT_IJLi42EEE" } }
h(b); // { dg-final { scan-assembler "_Z1hI1BEvT_IJLi42EEE" } }
C<int>::j(b); // { dg-final { scan-assembler "_ZN1CIiE1jI1BEEvT_IJLi42EEE" } }
}

2
gcc/testsuite/g++.dg/abi/mangle10.C
View File

@ -1,4 +1,4 @@
// { dg-options "-fabi-version=0" }
// { dg-options "-fabi-version=0 -fabi-compat-version=0" }
template <template <typename> class Q>
void f (typename Q<int>::X) {}

2
gcc/testsuite/g++.dg/abi/mangle52.C
View File

@ -1,4 +1,4 @@
// { dg-options "-fabi-version=0 -Wabi=2" }
// { dg-options "-fabi-version=18 -Wabi=2" }
template <unsigned int> struct helper {};
// { dg-final { scan-assembler "\n_?_Z6check1IiEvP6helperIXszscT_Li1EEE\[: \t\n\]" } }

5
gcc/testsuite/g++.dg/cpp2a/class-deduction-alias3.C
View File

@ -1,8 +1,11 @@
// PR c++/95486
// { dg-do compile { target c++20 } }
template <class T>
concept Int = __is_same (T, int);
template<class T, class U>
struct X { X(U) requires __is_same(U, int) {} };
struct X { X(U) requires Int<U> {} };
template<class U>
using Y = X<void, U>;

5
gcc/testsuite/g++.dg/cpp2a/class-deduction-alias8.C
View File

@ -1,8 +1,11 @@
// PR c++/95486
// { dg-do compile { target c++20 } }
template <class T>
concept Int = __is_same (T, int);
template<class T, class U>
struct X { X(U) requires __is_same(U, int) {} };
struct X { X(U) requires Int<U> {} };
template<class U>
X(U) -> X<char, U>;

2
include/demangle.h
View File

@ -466,6 +466,8 @@ enum demangle_component_type
DEMANGLE_COMPONENT_TEMPLATE_TEMPLATE_PARM,
DEMANGLE_COMPONENT_TEMPLATE_PACK_PARM,
DEMANGLE_COMPONENT_CONSTRAINTS,
/* A builtin type with argument. This holds the builtin type
information. */
DEMANGLE_COMPONENT_EXTENDED_BUILTIN_TYPE

86
libiberty/cp-demangle.c
View File

@ -993,6 +993,7 @@ d_make_comp (struct d_info *di, enum demangle_component_type type,
case DEMANGLE_COMPONENT_VECTOR_TYPE:
case DEMANGLE_COMPONENT_CLONE:
case DEMANGLE_COMPONENT_MODULE_ENTITY:
case DEMANGLE_COMPONENT_CONSTRAINTS:
if (left == NULL || right == NULL)
return NULL;
break;
@ -1345,6 +1346,22 @@ is_ctor_dtor_or_conversion (struct demangle_component *dc)
}
}
/* [ Q <constraint-expression> ] */
static struct demangle_component *
d_maybe_constraints (struct d_info *di, struct demangle_component *dc)
{
if (d_peek_char (di) == 'Q')
{
d_advance (di, 1);
struct demangle_component *expr = d_expression (di);
if (expr == NULL)
return NULL;
dc = d_make_comp (di, DEMANGLE_COMPONENT_CONSTRAINTS, dc, expr);
}
return dc;
}
/* <encoding> ::= <(function) name> <bare-function-type>
::= <(data) name>
::= <special-name>
@ -1398,21 +1415,21 @@ d_encoding (struct d_info *di, int top_level)
struct demangle_component *ftype;
ftype = d_bare_function_type (di, has_return_type (dc));
if (ftype)
{
/* If this is a non-top-level local-name, clear the
return type, so it doesn't confuse the user by
being confused with the return type of whaever
this is nested within. */
if (!top_level && dc->type == DEMANGLE_COMPONENT_LOCAL_NAME
&& ftype->type == DEMANGLE_COMPONENT_FUNCTION_TYPE)
d_left (ftype) = NULL;
if (!ftype)
return NULL;
dc = d_make_comp (di, DEMANGLE_COMPONENT_TYPED_NAME,
dc, ftype);
}
else
dc = NULL;
/* If this is a non-top-level local-name, clear the
return type, so it doesn't confuse the user by
being confused with the return type of whaever
this is nested within. */
if (!top_level && dc->type == DEMANGLE_COMPONENT_LOCAL_NAME
&& ftype->type == DEMANGLE_COMPONENT_FUNCTION_TYPE)
d_left (ftype) = NULL;
ftype = d_maybe_constraints (di, ftype);
dc = d_make_comp (di, DEMANGLE_COMPONENT_TYPED_NAME,
dc, ftype);
}
}
}
@ -3023,7 +3040,7 @@ d_parmlist (struct d_info *di)
struct demangle_component *type;
char peek = d_peek_char (di);
if (peek == '\0' || peek == 'E' || peek == '.')
if (peek == '\0' || peek == 'E' || peek == '.' || peek == 'Q')
break;
if ((peek == 'R' || peek == 'O')
&& d_peek_next_char (di) == 'E')
@ -3259,7 +3276,7 @@ d_template_args (struct d_info *di)
return d_template_args_1 (di);
}
/* <template-arg>* E */
/* <template-arg>* [Q <constraint-expression>] E */
static struct demangle_component *
d_template_args_1 (struct d_info *di)
@ -3295,13 +3312,17 @@ d_template_args_1 (struct d_info *di)
return NULL;
pal = &d_right (*pal);
if (d_peek_char (di) == 'E')
{
d_advance (di, 1);
break;
}
char peek = d_peek_char (di);
if (peek == 'E' || peek == 'Q')
break;
}
al = d_maybe_constraints (di, al);
if (d_peek_char (di) != 'E')
return NULL;
d_advance (di, 1);
di->last_name = hold_last_name;
return al;
@ -4442,6 +4463,7 @@ d_count_templates_scopes (struct d_print_info *dpi,
case DEMANGLE_COMPONENT_PACK_EXPANSION:
case DEMANGLE_COMPONENT_TAGGED_NAME:
case DEMANGLE_COMPONENT_CLONE:
case DEMANGLE_COMPONENT_CONSTRAINTS:
recurse_left_right:
/* PR 89394 - Check for too much recursion. */
if (dpi->recursion > DEMANGLE_RECURSION_LIMIT)
@ -5201,6 +5223,22 @@ d_print_comp_inner (struct d_print_info *dpi, int options,
dpt.next = dpi->templates;
dpi->templates = &dpt;
dpt.template_decl = typed_name;
/* Constraints are mangled as part of the template argument list,
so they wrap the _TEMPLATE_ARGLIST. But
d_lookup_template_argument expects the RHS of _TEMPLATE to be
the _ARGLIST, and constraints need to refer to these args. So
move the _CONSTRAINTS out of the _TEMPLATE and onto the type.
This will result in them being printed after the () like a
trailing requires-clause, but that seems like our best option
given that we aren't printing a template-head. */
struct demangle_component *tnr = d_right (typed_name);
if (tnr->type == DEMANGLE_COMPONENT_CONSTRAINTS)
{
d_right (typed_name) = d_left (tnr);
d_left (tnr) = d_right (dc);
d_right (dc) = tnr;
}
}
d_print_comp (dpi, options, d_right (dc));
@ -6248,6 +6286,12 @@ d_print_comp_inner (struct d_print_info *dpi, int options,
d_append_string (dpi, "...");
return;
case DEMANGLE_COMPONENT_CONSTRAINTS:
d_print_comp (dpi, options, d_left (dc));
d_append_string (dpi, " requires ");
d_print_comp (dpi, options, d_right (dc));
return;
default:
d_print_error (dpi);
return;

8
libiberty/testsuite/demangle-expected
View File

@ -1692,3 +1692,11 @@ X<float>::operator Z<int><int>()::y
_ZN1SILi1EEF3barIiEEiR4Base
int S<1>::bar[friend]<int>(Base&)
# requires on template-head
_Z1fIiQ1CIT_EEvv
void f<int>() requires C<int>
# requires after ()
_Z1fIiEvvQ1CIT_E
void f<int>() requires C<int>

2
libstdc++-v3/include/std/bit
View File

@ -88,7 +88,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
bit_cast(const _From& __from) noexcept
#ifdef __cpp_concepts
requires (sizeof(_To) == sizeof(_From))
&& __is_trivially_copyable(_To) && __is_trivially_copyable(_From)
&& is_trivially_copyable_v<_To> && is_trivially_copyable_v<_From>
#endif
{
return __builtin_bit_cast(_To, __from);

4
libstdc++-v3/include/std/variant
View File

@ -427,8 +427,8 @@ namespace __variant
~_Variadic_union() = default;
constexpr ~_Variadic_union()
requires (!__has_trivial_destructor(_First))
|| (!__has_trivial_destructor(_Variadic_union<_Rest...>))
requires (!is_trivially_destructible_v<_First>)
|| (!is_trivially_destructible_v<_Variadic_union<_Rest...>>)
{ }
#endif