| Message ID | 20200724134955.3681531-1-ppalka@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | c++: alias_ctad_tweaks and constrained dguide [PR95486] | expand |
On 7/24/20 9:49 AM, Patrick Palka wrote: > In the below testcase, we're ICEing from alias_ctad_tweaks ultimately > because the implied deduction guide for X's user-defined constructor > already has constraints associated with it. We then carry over these > constraints to 'fprime', the overlying deduction guide for the alias > template Y, via tsubst_decl from alias_ctad_tweaks. Later in > alias_ctad_tweaks we call get_constraints followed by set_constraints on > this overlying deduction guide without doing remove_constraints in > between, which triggers the !found assert in set_constraints. > > This patch fixes this issue by adding an intervening call to > remove_constraints. This hunk is OK. > And for consistency, it changes the call to > get_constraints to go through fprime instead of f. This hunk is not, as what we're doing is substituting the constraints of f to produce the constraints of f'. This change makes it less clear. OK without that change. > Since the DECL_TEMPLATE_RESULT of fprime is f, this consistency change makes > no functional difference. The DECL_TEMPLATE_RESULT of fprime is g, not f. > Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK > commit? > > gcc/cp/ChangeLog: > > PR c++/95486 > * pt.c (alias_ctad_tweaks): Obtain the associated constraints > through fprime instead of through f. Call remove_constraints > before calling set_constraints. > > gcc/testsuite/ChangeLog: > > PR c++/95486 > * g++.dg/cpp2a/class-deduction-alias3.C: New test. > --- > gcc/cp/pt.c | 7 +++++-- > gcc/testsuite/g++.dg/cpp2a/class-deduction-alias3.C | 11 +++++++++++ > 2 files changed, 16 insertions(+), 2 deletions(-) > create mode 100644 gcc/testsuite/g++.dg/cpp2a/class-deduction-alias3.C > > diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c > index b6df87a8a2e..4d955c555dc 100644 > --- a/gcc/cp/pt.c > +++ b/gcc/cp/pt.c > @@ -28598,7 +28598,7 @@ alias_ctad_tweaks (tree tmpl, tree uguides) > DECL_PRIMARY_TEMPLATE (fprime) = fprime; > > /* Substitute the associated constraints. */ > - tree ci = get_constraints (f); > + tree ci = get_constraints (fprime); > if (ci) > ci = tsubst_constraint_info (ci, targs, complain, in_decl); > if (ci == error_mark_node) > @@ -28616,7 +28616,10 @@ alias_ctad_tweaks (tree tmpl, tree uguides) > } > > if (ci) > - set_constraints (fprime, ci); > + { > + remove_constraints (fprime); > + set_constraints (fprime, ci); > + } > } > else > { > diff --git a/gcc/testsuite/g++.dg/cpp2a/class-deduction-alias3.C b/gcc/testsuite/g++.dg/cpp2a/class-deduction-alias3.C > new file mode 100644 > index 00000000000..318d4c942ce > --- /dev/null > +++ b/gcc/testsuite/g++.dg/cpp2a/class-deduction-alias3.C > @@ -0,0 +1,11 @@ > +// PR c++/95486 > +// { dg-do compile { target c++20 } } > + > +template<class T, class U> > +struct X { X(U) requires __is_same(U, int) {} }; > + > +template<class U> > +using Y = X<void, U>; > + > +Y y{1}; > +Y z{'a'}; // { dg-error "failed|no match" } >
On Wed, 29 Jul 2020, Jason Merrill wrote: > On 7/24/20 9:49 AM, Patrick Palka wrote: > > In the below testcase, we're ICEing from alias_ctad_tweaks ultimately > > because the implied deduction guide for X's user-defined constructor > > already has constraints associated with it. We then carry over these > > constraints to 'fprime', the overlying deduction guide for the alias > > template Y, via tsubst_decl from alias_ctad_tweaks. Later in > > alias_ctad_tweaks we call get_constraints followed by set_constraints on > > this overlying deduction guide without doing remove_constraints in > > between, which triggers the !found assert in set_constraints. > > > > This patch fixes this issue by adding an intervening call to > > remove_constraints. > > This hunk is OK. > > > And for consistency, it changes the call to > > get_constraints to go through fprime instead of f. > > This hunk is not, as what we're doing is substituting the constraints of f to > produce the constraints of f'. This change makes it less clear. > > OK without that change. That makes sense, consider that hunk gone then. > > > Since the DECL_TEMPLATE_RESULT of fprime is f, this consistency change makes > > no functional difference. > > The DECL_TEMPLATE_RESULT of fprime is g, not f. Ah yes, sorry for this thinko. I'll commit just the one hunk after a round of testing; thanks for the review. > > > Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK > > commit? > > > > gcc/cp/ChangeLog: > > > > PR c++/95486 > > * pt.c (alias_ctad_tweaks): Obtain the associated constraints > > through fprime instead of through f. Call remove_constraints > > before calling set_constraints. > > > > gcc/testsuite/ChangeLog: > > > > PR c++/95486 > > * g++.dg/cpp2a/class-deduction-alias3.C: New test. > > --- > > gcc/cp/pt.c | 7 +++++-- > > gcc/testsuite/g++.dg/cpp2a/class-deduction-alias3.C | 11 +++++++++++ > > 2 files changed, 16 insertions(+), 2 deletions(-) > > create mode 100644 gcc/testsuite/g++.dg/cpp2a/class-deduction-alias3.C > > > > diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c > > index b6df87a8a2e..4d955c555dc 100644 > > --- a/gcc/cp/pt.c > > +++ b/gcc/cp/pt.c > > @@ -28598,7 +28598,7 @@ alias_ctad_tweaks (tree tmpl, tree uguides) > > DECL_PRIMARY_TEMPLATE (fprime) = fprime; > > /* Substitute the associated constraints. */ > > - tree ci = get_constraints (f); > > + tree ci = get_constraints (fprime); > > if (ci) > > ci = tsubst_constraint_info (ci, targs, complain, in_decl); > > if (ci == error_mark_node) > > @@ -28616,7 +28616,10 @@ alias_ctad_tweaks (tree tmpl, tree uguides) > > } > > if (ci) > > - set_constraints (fprime, ci); > > + { > > + remove_constraints (fprime); > > + set_constraints (fprime, ci); > > + } > > } > > else > > { > > diff --git a/gcc/testsuite/g++.dg/cpp2a/class-deduction-alias3.C > > b/gcc/testsuite/g++.dg/cpp2a/class-deduction-alias3.C > > new file mode 100644 > > index 00000000000..318d4c942ce > > --- /dev/null > > +++ b/gcc/testsuite/g++.dg/cpp2a/class-deduction-alias3.C > > @@ -0,0 +1,11 @@ > > +// PR c++/95486 > > +// { dg-do compile { target c++20 } } > > + > > +template<class T, class U> > > +struct X { X(U) requires __is_same(U, int) {} }; > > + > > +template<class U> > > +using Y = X<void, U>; > > + > > +Y y{1}; > > +Y z{'a'}; // { dg-error "failed|no match" } > > > >
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c index b6df87a8a2e..4d955c555dc 100644 --- a/gcc/cp/pt.c +++ b/gcc/cp/pt.c @@ -28598,7 +28598,7 @@ alias_ctad_tweaks (tree tmpl, tree uguides) DECL_PRIMARY_TEMPLATE (fprime) = fprime; /* Substitute the associated constraints. */ - tree ci = get_constraints (f); + tree ci = get_constraints (fprime); if (ci) ci = tsubst_constraint_info (ci, targs, complain, in_decl); if (ci == error_mark_node) @@ -28616,7 +28616,10 @@ alias_ctad_tweaks (tree tmpl, tree uguides) } if (ci) - set_constraints (fprime, ci); + { + remove_constraints (fprime); + set_constraints (fprime, ci); + } } else { diff --git a/gcc/testsuite/g++.dg/cpp2a/class-deduction-alias3.C b/gcc/testsuite/g++.dg/cpp2a/class-deduction-alias3.C new file mode 100644 index 00000000000..318d4c942ce --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/class-deduction-alias3.C @@ -0,0 +1,11 @@ +// PR c++/95486 +// { dg-do compile { target c++20 } } + +template<class T, class U> +struct X { X(U) requires __is_same(U, int) {} }; + +template<class U> +using Y = X<void, U>; + +Y y{1}; +Y z{'a'}; // { dg-error "failed|no match" }