| Message ID | ef9e1f4c-b1e2-24f3-649a-c45d0d51eba3@acm.org |
|---|---|
| State | New |
| Headers | show |
On Mon, Dec 12, 2016 at 2:12 PM, Nathan Sidwell <nathan@acm.org> wrote: > Solved by breaking TYPE_TEMPLATE_INFO into an underlying helper that doesn't > deal with type aliases. I like this idea, but I don't like the name. Since alias templates are generally transparent in the language, I wonder about changing TYPE_TEMPLATE_INFO to look through aliases and creating a new macro that also handles aliases, say TYPE_TEMPLATE_INFO_MAYBE_ALIAS? Jason
On 12/12/2016 04:44 PM, Jason Merrill wrote: > On Mon, Dec 12, 2016 at 2:12 PM, Nathan Sidwell <nathan@acm.org> wrote: >> Solved by breaking TYPE_TEMPLATE_INFO into an underlying helper that doesn't >> deal with type aliases. > > I like this idea, but I don't like the name. Since alias templates > are generally transparent in the language, I wonder about changing > TYPE_TEMPLATE_INFO to look through aliases and creating a new macro Do you mean '... to NOT look ...'? If so ... > that also handles aliases, say TYPE_TEMPLATE_INFO_MAYBE_ALIAS? I had similar thought (down to the MAYBE name), but guessed that the invasiveness would be great. I suppose SED to the rescue? nathan -- Nathan Sidwell
On Mon, Dec 12, 2016 at 5:48 PM, Nathan Sidwell <nathan@acm.org> wrote: > On 12/12/2016 04:44 PM, Jason Merrill wrote: >> >> On Mon, Dec 12, 2016 at 2:12 PM, Nathan Sidwell <nathan@acm.org> wrote: >>> >>> Solved by breaking TYPE_TEMPLATE_INFO into an underlying helper that >>> doesn't deal with type aliases. >> >> I like this idea, but I don't like the name. Since alias templates >> are generally transparent in the language, I wonder about changing >> TYPE_TEMPLATE_INFO to look through aliases and creating a new macro > > Do you mean '... to NOT look ...'? If so ... > >> that also handles aliases, say TYPE_TEMPLATE_INFO_MAYBE_ALIAS? > > I had similar thought (down to the MAYBE name), but guessed that the > invasiveness would be great. I suppose SED to the rescue? I suspect that most uses don't need to change. Jason
On Mon, Dec 12, 2016 at 11:12 AM, Nathan Sidwell <nathan@acm.org> wrote: > This patch fixes an ICE in a checking build where structural_comptypes > disagrees with TYPE_CANONICAL. > > An (implicit) template alias has a different TYPE_TI_TEMPLATE to the thing > its aliasing. That make structural comparison think it's different. In the > testcase we end up thinking 'Loc' refers to a different template than > 'Traits<T>' > > Solved by breaking TYPE_TEMPLATE_INFO into an underlying helper that doesn't > deal with type aliases. While there, I noticed TYPE_TEMPLATE_INFO was doing > more work than necessary because it checked twice whether DECL_LANG_SPECIFIC > (TYPE_NAME (NODE)) was non-null. There's no need to check it again in the > branch we can only get to when it's non-null. I also removed some > unnecessary parens. > > ok? Note this is originally PR 69481 which I found a year or so ago. I was trying to debug this and try to understand why typedef and using would produce different result but I never could figure it out. I also could not figure out why they went down a different path either and not treated as the same. Thanks, Andrew > > nathan > -- > Nathan Sidwell
2016-12-12 Nathan Sidwell <nathan@acm.org> PR c++/78776 * cp-tree.h (TYPE_TEMPLATE_INFO_RAW): New, broken out of ... (TYPE_TEMPLATE_INFO): ... here. Use it. * typeck.c (structural_comptypes): Adjust record/union check to avoid alias template confusion. PR c++/78776 * g++.dg/cpp0x/pr78776.C: New. Index: cp/cp-tree.h =================================================================== --- cp/cp-tree.h (revision 243554) +++ cp/cp-tree.h (working copy) @@ -3038,22 +3038,25 @@ extern void decl_shadowed_for_var_insert ->template_info) /* Template information for an ENUMERAL_, RECORD_, UNION_TYPE, or - BOUND_TEMPLATE_TEMPLATE_PARM type. Note that if NODE is a - specialization of an alias template, this accessor returns the - template info for the alias template, not the one (if any) for the - template of the underlying type. */ + BOUND_TEMPLATE_TEMPLATE_PARM type. This ignores any alias + templateness of NODE. */ + +#define TYPE_TEMPLATE_INFO_RAW(NODE) \ + (TREE_CODE (NODE) == ENUMERAL_TYPE \ + ? ENUM_TEMPLATE_INFO (NODE) \ + : (TREE_CODE (NODE) == BOUND_TEMPLATE_TEMPLATE_PARM \ + ? TEMPLATE_TEMPLATE_PARM_TEMPLATE_INFO (NODE) \ + : (CLASS_TYPE_P (NODE) \ + ? CLASSTYPE_TEMPLATE_INFO (NODE) \ + : NULL_TREE))) + +/* If NODE is a specialization of an alias template, this accessor + returns the template info for the alias template. Otherwise behave + as TYPE_TEMPLATE_INFO_RAW. */ #define TYPE_TEMPLATE_INFO(NODE) \ - ((TYPE_ALIAS_P (NODE) && DECL_LANG_SPECIFIC (TYPE_NAME (NODE))) \ - ? (DECL_LANG_SPECIFIC (TYPE_NAME (NODE)) \ - ? DECL_TEMPLATE_INFO (TYPE_NAME (NODE)) \ - : NULL_TREE) \ - : ((TREE_CODE (NODE) == ENUMERAL_TYPE) \ - ? ENUM_TEMPLATE_INFO (NODE) \ - : ((TREE_CODE (NODE) == BOUND_TEMPLATE_TEMPLATE_PARM) \ - ? TEMPLATE_TEMPLATE_PARM_TEMPLATE_INFO (NODE) \ - : (CLASS_TYPE_P (NODE) \ - ? CLASSTYPE_TEMPLATE_INFO (NODE) \ - : NULL_TREE)))) + (TYPE_ALIAS_P (NODE) && DECL_LANG_SPECIFIC (TYPE_NAME (NODE)) \ + ? DECL_TEMPLATE_INFO (TYPE_NAME (NODE)) \ + : TYPE_TEMPLATE_INFO_RAW (NODE)) /* Set the template information for an ENUMERAL_, RECORD_, or Index: cp/typeck.c =================================================================== --- cp/typeck.c (revision 243554) +++ cp/typeck.c (working copy) @@ -1284,18 +1284,23 @@ structural_comptypes (tree t1, tree t2, case RECORD_TYPE: case UNION_TYPE: - if (TYPE_TEMPLATE_INFO (t1) && TYPE_TEMPLATE_INFO (t2) - && (TYPE_TI_TEMPLATE (t1) == TYPE_TI_TEMPLATE (t2) - || TREE_CODE (t1) == BOUND_TEMPLATE_TEMPLATE_PARM) - && comp_template_args (TYPE_TI_ARGS (t1), TYPE_TI_ARGS (t2))) - break; + { + /* Ignore any alias templateness. */ + tree ti1 = TYPE_TEMPLATE_INFO_RAW (t1); + tree ti2 = TYPE_TEMPLATE_INFO_RAW (t2); - if ((strict & COMPARE_BASE) && DERIVED_FROM_P (t1, t2)) - break; - else if ((strict & COMPARE_DERIVED) && DERIVED_FROM_P (t2, t1)) - break; + if (ti1 && ti2 + && (TI_TEMPLATE (ti1) == TI_TEMPLATE (ti2) + || TREE_CODE (t1) == BOUND_TEMPLATE_TEMPLATE_PARM) + && comp_template_args (TI_ARGS (ti1), TI_ARGS (ti2))) + break; + if ((strict & COMPARE_BASE) && DERIVED_FROM_P (t1, t2)) + break; + else if ((strict & COMPARE_DERIVED) && DERIVED_FROM_P (t2, t1)) + break; - return false; + return false; + } case OFFSET_TYPE: if (!comptypes (TYPE_OFFSET_BASETYPE (t1), TYPE_OFFSET_BASETYPE (t2), Index: testsuite/g++.dg/cpp0x/pr78776.C =================================================================== --- testsuite/g++.dg/cpp0x/pr78776.C (revision 0) +++ testsuite/g++.dg/cpp0x/pr78776.C (working copy) @@ -0,0 +1,15 @@ +// PR c++/78776 +// { dg-do compile { target c++11 } } + +// ICE with canonical type verification + +template <typename> struct Traits; + +template <typename T> +struct Bob { + using Loc = Traits<T>; + using typename Loc::Thing; + + Thing Foo (); +}; +