| Message ID | 20200707133327.1377955-1-ppalka@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | c++: ICE in is_really_empty_class [PR95497] | expand |
On Tue, 7 Jul 2020, Patrick Palka wrote: > We are ICEing in the testcase below because we pass the > yet-uninstantiated class type A<int> of the PARM_DECL b to > is_really_empty_class from potential_rvalue_constant_expression when > parsing the requirement t += b. > > This patch fixes the ICE by guarding the problematic call to > is_really_empty_class with a COMPLETE_TYPE_P check, which should also > subsume the existing dependent_type_p check. > > Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK to > commit to trunk and to the 10 branch? Oops, the regression is not present on the 10 branch so this fix wouldn't need backporting. > > gcc/cp/ChangeLog: > > PR c++/95497 > * constexpr.c (potential_constant_expression_1): When > processing_template_decl, check COMPLETE_TYPE_P before calling > is_really_empty_class. > > gcc/testsuite/ChangeLog: > > PR c++/95497 > * g++.dg/cpp2a/concepts-pr95497.C: New test. > --- > gcc/cp/constexpr.c | 2 +- > gcc/testsuite/g++.dg/cpp2a/concepts-pr95497.C | 12 ++++++++++++ > 2 files changed, 13 insertions(+), 1 deletion(-) > create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-pr95497.C > > diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c > index 1939166e907..ff78ebda2dc 100644 > --- a/gcc/cp/constexpr.c > +++ b/gcc/cp/constexpr.c > @@ -7443,7 +7443,7 @@ potential_constant_expression_1 (tree t, bool want_rval, bool strict, bool now, > if (now && want_rval) > { > tree type = TREE_TYPE (t); > - if (dependent_type_p (type) > + if ((processing_template_decl && !COMPLETE_TYPE_P (type)) > || is_really_empty_class (type, /*ignore_vptr*/false)) > /* An empty class has no data to read. */ > return true; > diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-pr95497.C b/gcc/testsuite/g++.dg/cpp2a/concepts-pr95497.C > new file mode 100644 > index 00000000000..4d7718ad5e8 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/cpp2a/concepts-pr95497.C > @@ -0,0 +1,12 @@ > +// PR c++/95497 > +// { dg-do compile { target c++20 } } > + > +template <typename T> > +struct A{}; > + > +template <typename T> > +concept c = > + requires(T t, A<int> b) // note that A<int> is independent of T > + { > + { t += b }; > + }; > -- > 2.27.0.203.gf402ea6816 > >
On 7/7/20 9:33 AM, Patrick Palka wrote: > We are ICEing in the testcase below because we pass the > yet-uninstantiated class type A<int> of the PARM_DECL b to > is_really_empty_class from potential_rvalue_constant_expression when > parsing the requirement t += b. Why are we getting to potential_rvalue_constant_expression? My guess is from build_non_dependent_expr because processing_constraint isn't set? > This patch fixes the ICE by guarding the problematic call to > is_really_empty_class with a COMPLETE_TYPE_P check, which should also > subsume the existing dependent_type_p check. > > Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK to > commit to trunk and to the 10 branch? > > gcc/cp/ChangeLog: > > PR c++/95497 > * constexpr.c (potential_constant_expression_1): When > processing_template_decl, check COMPLETE_TYPE_P before calling > is_really_empty_class. > > gcc/testsuite/ChangeLog: > > PR c++/95497 > * g++.dg/cpp2a/concepts-pr95497.C: New test. > --- > gcc/cp/constexpr.c | 2 +- > gcc/testsuite/g++.dg/cpp2a/concepts-pr95497.C | 12 ++++++++++++ > 2 files changed, 13 insertions(+), 1 deletion(-) > create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-pr95497.C > > diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c > index 1939166e907..ff78ebda2dc 100644 > --- a/gcc/cp/constexpr.c > +++ b/gcc/cp/constexpr.c > @@ -7443,7 +7443,7 @@ potential_constant_expression_1 (tree t, bool want_rval, bool strict, bool now, > if (now && want_rval) > { > tree type = TREE_TYPE (t); > - if (dependent_type_p (type) > + if ((processing_template_decl && !COMPLETE_TYPE_P (type)) > || is_really_empty_class (type, /*ignore_vptr*/false)) > /* An empty class has no data to read. */ > return true; > diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-pr95497.C b/gcc/testsuite/g++.dg/cpp2a/concepts-pr95497.C > new file mode 100644 > index 00000000000..4d7718ad5e8 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/cpp2a/concepts-pr95497.C > @@ -0,0 +1,12 @@ > +// PR c++/95497 > +// { dg-do compile { target c++20 } } > + > +template <typename T> > +struct A{}; > + > +template <typename T> > +concept c = > + requires(T t, A<int> b) // note that A<int> is independent of T > + { > + { t += b }; > + }; >
On Tue, 7 Jul 2020, Jason Merrill wrote: > On 7/7/20 9:33 AM, Patrick Palka wrote: > > We are ICEing in the testcase below because we pass the > > yet-uninstantiated class type A<int> of the PARM_DECL b to > > is_really_empty_class from potential_rvalue_constant_expression when > > parsing the requirement t += b. > > Why are we getting to potential_rvalue_constant_expression? My guess is from > build_non_dependent_expr because processing_constraint isn't set? My mistake, I meant to write that we are calling is_really_empty_class from is_rvalue_constant_expression, not from potential_rvalue_constant_expression. And we're getting to is_rvalue_constant_expression from cp_parser_constant_expression when parsing the RHS of the assignment. > > > This patch fixes the ICE by guarding the problematic call to > > is_really_empty_class with a COMPLETE_TYPE_P check, which should also > > subsume the existing dependent_type_p check. > > > > Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK to > > commit to trunk and to the 10 branch? > > > > gcc/cp/ChangeLog: > > > > PR c++/95497 > > * constexpr.c (potential_constant_expression_1): When > > processing_template_decl, check COMPLETE_TYPE_P before calling > > is_really_empty_class. > > > > gcc/testsuite/ChangeLog: > > > > PR c++/95497 > > * g++.dg/cpp2a/concepts-pr95497.C: New test. > > --- > > gcc/cp/constexpr.c | 2 +- > > gcc/testsuite/g++.dg/cpp2a/concepts-pr95497.C | 12 ++++++++++++ > > 2 files changed, 13 insertions(+), 1 deletion(-) > > create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-pr95497.C > > > > diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c > > index 1939166e907..ff78ebda2dc 100644 > > --- a/gcc/cp/constexpr.c > > +++ b/gcc/cp/constexpr.c > > @@ -7443,7 +7443,7 @@ potential_constant_expression_1 (tree t, bool > > want_rval, bool strict, bool now, > > if (now && want_rval) > > { > > tree type = TREE_TYPE (t); > > - if (dependent_type_p (type) > > + if ((processing_template_decl && !COMPLETE_TYPE_P (type)) > > || is_really_empty_class (type, /*ignore_vptr*/false)) > > /* An empty class has no data to read. */ > > return true; > > diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-pr95497.C > > b/gcc/testsuite/g++.dg/cpp2a/concepts-pr95497.C > > new file mode 100644 > > index 00000000000..4d7718ad5e8 > > --- /dev/null > > +++ b/gcc/testsuite/g++.dg/cpp2a/concepts-pr95497.C > > @@ -0,0 +1,12 @@ > > +// PR c++/95497 > > +// { dg-do compile { target c++20 } } > > + > > +template <typename T> > > +struct A{}; > > + > > +template <typename T> > > +concept c = > > + requires(T t, A<int> b) // note that A<int> is independent of T > > + { > > + { t += b }; > > + }; > > > >
On 7/7/20 3:36 PM, Patrick Palka wrote: > On Tue, 7 Jul 2020, Jason Merrill wrote: > >> On 7/7/20 9:33 AM, Patrick Palka wrote: >>> We are ICEing in the testcase below because we pass the >>> yet-uninstantiated class type A<int> of the PARM_DECL b to >>> is_really_empty_class from potential_rvalue_constant_expression when >>> parsing the requirement t += b. >> >> Why are we getting to potential_rvalue_constant_expression? My guess is from >> build_non_dependent_expr because processing_constraint isn't set? > > My mistake, I meant to write that we are calling is_really_empty_class > from is_rvalue_constant_expression, not from > potential_rvalue_constant_expression. And we're getting to > is_rvalue_constant_expression from cp_parser_constant_expression when > parsing the RHS of the assignment. Most of the parser constant-expression stuff is a relic of C++98; I tried changing cp_parser_constant_expression to only check constancy when we're requiring a constant expression, but that broke some library tests for some reason. >>> This patch fixes the ICE by guarding the problematic call to >>> is_really_empty_class with a COMPLETE_TYPE_P check, which should also >>> subsume the existing dependent_type_p check. OK. >>> Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK to >>> commit to trunk and to the 10 branch? >>> >>> gcc/cp/ChangeLog: >>> >>> PR c++/95497 >>> * constexpr.c (potential_constant_expression_1): When >>> processing_template_decl, check COMPLETE_TYPE_P before calling >>> is_really_empty_class. >>> >>> gcc/testsuite/ChangeLog: >>> >>> PR c++/95497 >>> * g++.dg/cpp2a/concepts-pr95497.C: New test. >>> --- >>> gcc/cp/constexpr.c | 2 +- >>> gcc/testsuite/g++.dg/cpp2a/concepts-pr95497.C | 12 ++++++++++++ >>> 2 files changed, 13 insertions(+), 1 deletion(-) >>> create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-pr95497.C >>> >>> diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c >>> index 1939166e907..ff78ebda2dc 100644 >>> --- a/gcc/cp/constexpr.c >>> +++ b/gcc/cp/constexpr.c >>> @@ -7443,7 +7443,7 @@ potential_constant_expression_1 (tree t, bool >>> want_rval, bool strict, bool now, >>> if (now && want_rval) >>> { >>> tree type = TREE_TYPE (t); >>> - if (dependent_type_p (type) >>> + if ((processing_template_decl && !COMPLETE_TYPE_P (type)) >>> || is_really_empty_class (type, /*ignore_vptr*/false)) >>> /* An empty class has no data to read. */ >>> return true; >>> diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-pr95497.C >>> b/gcc/testsuite/g++.dg/cpp2a/concepts-pr95497.C >>> new file mode 100644 >>> index 00000000000..4d7718ad5e8 >>> --- /dev/null >>> +++ b/gcc/testsuite/g++.dg/cpp2a/concepts-pr95497.C >>> @@ -0,0 +1,12 @@ >>> +// PR c++/95497 >>> +// { dg-do compile { target c++20 } } >>> + >>> +template <typename T> >>> +struct A{}; >>> + >>> +template <typename T> >>> +concept c = >>> + requires(T t, A<int> b) // note that A<int> is independent of T >>> + { >>> + { t += b }; >>> + }; >>> >> >> >
diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c index 1939166e907..ff78ebda2dc 100644 --- a/gcc/cp/constexpr.c +++ b/gcc/cp/constexpr.c @@ -7443,7 +7443,7 @@ potential_constant_expression_1 (tree t, bool want_rval, bool strict, bool now, if (now && want_rval) { tree type = TREE_TYPE (t); - if (dependent_type_p (type) + if ((processing_template_decl && !COMPLETE_TYPE_P (type)) || is_really_empty_class (type, /*ignore_vptr*/false)) /* An empty class has no data to read. */ return true; diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-pr95497.C b/gcc/testsuite/g++.dg/cpp2a/concepts-pr95497.C new file mode 100644 index 00000000000..4d7718ad5e8 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/concepts-pr95497.C @@ -0,0 +1,12 @@ +// PR c++/95497 +// { dg-do compile { target c++20 } } + +template <typename T> +struct A{}; + +template <typename T> +concept c = + requires(T t, A<int> b) // note that A<int> is independent of T + { + { t += b }; + };