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c++: Stream DECL_CONTEXT for template template parms [PR98881]

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When streaming in a nested template-template parameter as in the
attached testcase, we end up reaching the containing template-template
parameter in 'tpl_parms_fini'. We should not set the DECL_CONTEXT to
this (nested) template-template parameter, as it should already be the
struct that the outer template-template parameter is declared on.

The precise logic for what DECL_CONTEXT should be for a template
template parameter in various situations seems rather obscure. Rather
than trying to determine the assumptions that need to hold, it seems
simpler to just always re-stream the DECL_CONTEXT as needed for now.

	PR c++/98881

gcc/cp/ChangeLog:

	* module.cc (trees_out::tpl_parms_fini): Stream out DECL_CONTEXT
	for template template parameters.
	(trees_in::tpl_parms_fini): Read it.

gcc/testsuite/ChangeLog:

	* g++.dg/modules/tpl-tpl-parm-3.h: New test.
	* g++.dg/modules/tpl-tpl-parm-3_a.H: New test.
	* g++.dg/modules/tpl-tpl-parm-3_b.C: New test.
	* g++.dg/modules/tpl-tpl-parm-3_c.C: New test.

Signed-off-by: Nathaniel Shead <nathanieloshead@gmail.com>
Reviewed-by: Patrick Palka <ppalka@redhat.com>
Reviewed-by: Jason Merrill <jason@redhat.com>
This commit is contained in:
Nathaniel Shead 2024-03-05 15:17:09 +11:00
parent b209d905f5
commit 77772f8a3d
5 changed files with 47 additions and 31 deletions
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41
gcc/cp/module.cc
View file

@ -10126,23 +10126,12 @@ trees_out::tpl_parms_fini (tree tmpl, unsigned tpl_levels)
tree dflt = TREE_PURPOSE (parm);
tree_node (dflt);
if (streaming_p ())
{
tree decl = TREE_VALUE (parm);
if (TREE_CODE (decl) == TEMPLATE_DECL)
{
tree ctx = DECL_CONTEXT (decl);
tree inner = DECL_TEMPLATE_RESULT (decl);
tree tpi = (TREE_CODE (inner) == TYPE_DECL
? TEMPLATE_TYPE_PARM_INDEX (TREE_TYPE (decl))
: DECL_INITIAL (inner));
bool original = (TEMPLATE_PARM_LEVEL (tpi)
== TEMPLATE_PARM_ORIG_LEVEL (tpi));
/* Original template template parms have a context
of their owning template. Reduced ones do not. */
gcc_checking_assert (original ? ctx == tmpl : !ctx);
}
}
/* Template template parameters need a context of their owning
template. This is quite tricky to infer correctly on stream-in
(see PR c++/98881) so we'll just provide it directly. */
tree decl = TREE_VALUE (parm);
if (TREE_CODE (decl) == TEMPLATE_DECL)
tree_node (DECL_CONTEXT (decl));
}
}
}
@ -10160,24 +10149,14 @@ trees_in::tpl_parms_fini (tree tmpl, unsigned tpl_levels)
{
tree parm = TREE_VEC_ELT (vec, ix);
tree dflt = tree_node ();
if (get_overrun ())
return false;
TREE_PURPOSE (parm) = dflt;
tree decl = TREE_VALUE (parm);
if (TREE_CODE (decl) == TEMPLATE_DECL)
{
tree inner = DECL_TEMPLATE_RESULT (decl);
tree tpi = (TREE_CODE (inner) == TYPE_DECL
? TEMPLATE_TYPE_PARM_INDEX (TREE_TYPE (decl))
: DECL_INITIAL (inner));
bool original = (TEMPLATE_PARM_LEVEL (tpi)
== TEMPLATE_PARM_ORIG_LEVEL (tpi));
/* Original template template parms have a context
of their owning template. Reduced ones do not. */
if (original)
DECL_CONTEXT (decl) = tmpl;
}
DECL_CONTEXT (decl) = tree_node ();
if (get_overrun ())
return false;
}
}
return true;

12
gcc/testsuite/g++.dg/modules/tpl-tpl-parm-3.h Normal file
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@ -0,0 +1,12 @@
// PR c++/98881
template <typename P> struct X {};
template<template <typename> typename TT>
struct X<TT<int>> {
template<template <typename> typename UU>
void f (X<UU<int>>&);
};
template<template<class> class TT> struct Y;
template<template<class> class UU> struct Y { };

5
gcc/testsuite/g++.dg/modules/tpl-tpl-parm-3_a.H Normal file
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@ -0,0 +1,5 @@
// PR c++/98881
// { dg-additional-options "-fmodule-header" }
// { dg-module-cmi {} }
#include "tpl-tpl-parm-3.h"

5
gcc/testsuite/g++.dg/modules/tpl-tpl-parm-3_b.C Normal file
View file

@ -0,0 +1,5 @@
// PR c++/98881
// { dg-additional-options "-fmodules-ts -fno-module-lazy" }
#include "tpl-tpl-parm-3.h"
import "tpl-tpl-parm-3_a.H";

15
gcc/testsuite/g++.dg/modules/tpl-tpl-parm-3_c.C Normal file
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@ -0,0 +1,15 @@
// PR c++/98881
// { dg-additional-options "-fmodules-ts" }
import "tpl-tpl-parm-3_a.H";
template <typename T> struct A {};
template <typename T> struct B {};
void foo() {
X<A<int>> a;
X<B<int>> b;
a.f(b);
Y<A> y;
}