On Thursday, March 5th, 2026 at 11:31 PM, Marek Polacek <[email protected]> wrote:
> On Thu, Mar 05, 2026 at 06:18:13PM -0500, Jason Merrill wrote: > > On 3/5/26 5:35 PM, Marek Polacek wrote: > > > On Thu, Mar 05, 2026 at 05:13:32PM -0500, Jason Merrill wrote: > > > > On 3/5/26 2:07 PM, Marek Polacek wrote: > > > > > On Wed, Mar 04, 2026 at 07:13:33PM +0000, Boris Staletic wrote: > > > > > > Bootstrapped and tested on x86_64-pc-linux-gnu. > > > > > > I have only ran g++.dg/reflect/* tests. > > > > > > If needed/wanted, I can run the entire `make check`, though > > > > > > that will take me the rest of the night. > > > > > > -- >8 -- > > > > > > With an annotation like [[=func]] gcc ends up calling > > > > > > handle_annotation_attribute with TREE_VALUE (args) being a > > > > > > VIEW_CONVERT_EXPR, whose type is a FUNCTION_TYPE. > > > > > > That kind of annotation value should be decayed before checking > > > > > > if the type is structural. > > > > > > > > > > > > Signed-off-by: Boris Staletic <[email protected]> > > > > > > > > > > > > PR c++/124177 > > > > > > > > > > > > gcc/cp/ChangeLog: > > > > > > > > > > > > * tree.cc (handle_annotation_attribute): Decay annotation > > > > > > values. > > > > > > > > > > This can fit on one line (80 is the limit). > > > > > > > > I prefer to wrap at 76 in commit messages because git log adds 4 spaces > > > > at > > > > the beginning. > > > > > > Fair. > > > > > > > > > gcc/testsuite/ChangeLog: > > > > > > > > > > > > * g++.dg/reflect/annotations11.C: New test. > > > > > > --- > > > > > > gcc/cp/tree.cc | 1 + > > > > > > gcc/testsuite/g++.dg/reflect/annotations11.C | 17 > > > > > > +++++++++++++++++ > > > > > > 2 files changed, 18 insertions(+) > > > > > > create mode 100644 gcc/testsuite/g++.dg/reflect/annotations11.C > > > > > > > > > > > > diff --git a/gcc/cp/tree.cc b/gcc/cp/tree.cc > > > > > > index 20288ed04e..5c7df0a1d9 100644 > > > > > > --- a/gcc/cp/tree.cc > > > > > > +++ b/gcc/cp/tree.cc > > > > > > @@ -5912,6 +5912,7 @@ handle_annotation_attribute (tree *node, tree > > > > > > ARG_UNUSED (name), > > > > > > *no_add_attrs = true; > > > > > > return NULL_TREE; > > > > > > } > > > > > > + TREE_VALUE (args) = decay_conversion (TREE_VALUE (args), > > > > > > tf_warning_or_error); > > > > > > > > > > I'm not sure if it's reasonable to call decay_conversion on something > > > > > type-dependent, so perhaps this should be moved inside of the > > > > > following > > > > > block. > > > > > > > > Good point. > > > > > > > > > But annotations are treated as late attributes so I'm not sure > > > > > how we'd get here with anything type-dependent, and I couldn't > > > > > construct > > > > > such a test. Maybe the !t_d_e_p check could be dropped? > > > > > > > > Or turned into an assert. > > > > > > Sounds good. I can do it later. > > > > > > > > We're supposed to treat the expression as reflect_constant(arg) but > > > > > doing the whole convert_reflect_constant_arg thing here seems > > > > > unpleasant. > > > > > > > > Hmm, why unpleasant? It seems straightforward and might be needed to > > > > get > > > > some messy cases right. > > > > > > I think it might need > > > > > > /* Figure out the type for reflect_constant. */ > > > type = TREE_TYPE (convert_from_reference (r)); > > > type = type_decays_to (type); > > > type = cv_unqualified (type); > > > > convert_for_reference shouldn't be needed here. > > Without it we don't compile this: > > constexpr int a = 3; > constexpr const int &ref = a; > static_assert (type_of (constant_of (^^ref)) == ^^int); > > due to > > error: 'const int&' must be a cv-unqualified structural type that is not a > reference type > > > type_decays_to/cv_unqualified to correspond to the [type.deduct.call] > > changes in maybe_adjust_types_for_deduction, sure. And then we wouldn't > > need the decay_conversion after all. > > > > > for the type, then check !structural_type_p and copy constructibility, > > > then call convert_reflect_constant_arg, and check for error_mark_node. > > > > Agreed. > > > > > But I think convert_reflect_constant_arg isn't entirely correct yet > > > (FIXME in reflect_constant6.C). > > > > Perhaps, but that doesn't seem like an argument against using it here. > > I agree, it will probably work for all our annotation uses. > > > Boris, let me know if you want me to take this over. I did implement the proposed changes, but it resulted in three regressions. Here's the commit with the changes (I was lazy and didn't adjust the commit message): https://codeberg.org/bstaletic/gcc/commit/8bacdc8ac390df094c9cec74ca6f717168eb7213 I pushed my updated commit to my fork[0]. Make sure to ignore whitespace when looking at the diff, due to indentation changes. The regressions are: 1. For `[[=(throw 2, 0)]]`, the annotation evaluation no longer throws. Test at: [1] 2. One test[2] is now hitting an assert[3] 3. Annotations whose value is a user defined type no longer have a proper source location. 3.1. Existing test case: [4] For the throw expression, if I change it to `[[=(throw 2)]]`, then I just get "annotation does not have a structural type", but there's no uncaught exception error. Regarding source location, both DECL_ARTIFICIAL (expr) and DECL_IGNORED_P (expr), so we end up returning early from maybe_wrap_with_location here: [5] I have not checked whether that is also the case for these test cases: [6][7] Then, for the assert, the full trace is: ``` 0x2a9417f internal_error(char const*, ...) ../../gcc/diagnostic-global-context.cc:787 0xafd767 fancy_abort(char const*, int, char const*) ../../gcc/diagnostics/context.cc:1813 0x830050 create_template_parm_object ../../gcc/cp/pt.cc:7504 0x830050 convert_nontype_argument ../../gcc/cp/pt.cc:8042 0xd8dc5c convert_reflect_constant_arg(tree_node*, tree_node*) ../../gcc/cp/pt.cc:33576 0xe38a34 handle_annotation_attribute ../../gcc/cp/tree.cc:5947 0xbf691a xref_basetypes(tree_node*, tree_node*) ../../gcc/cp/decl.cc:18611 0xdc5225 instantiate_class_template(tree_node*) ../../gcc/cp/pt.cc:12919 0xe3eb03 complete_type(tree_node*) ../../gcc/cp/typeck.cc:138 0xe3eca4 complete_type(tree_node*) ../../gcc/cp/typeck.cc:164 0xe3eca4 complete_type_or_maybe_complain(tree_node*, tree_node*, int) ../../gcc/cp/typeck.cc:151 0xde3a92 eval_bases_of ../../gcc/cp/reflect.cc:6845 0xde3a92 process_metafunction(constexpr_ctx const*, tree_node*, tree_node*, bool*, bool*, tree_node**) ../../gcc/cp/reflect.cc:7661 0xb5c204 cxx_eval_call_expression ../../gcc/cp/constexpr.cc:4014 0xb5fcfd cxx_eval_constant_expression(constexpr_ctx const*, tree_node*, value_cat, bool*, bool*, tree_node**) ../../gcc/cp/constexpr.cc:9352 0xb62b7c cxx_eval_constant_expression(constexpr_ctx const*, tree_node*, value_cat, bool*, bool*, tree_node**) ../../gcc/cp/constexpr.cc:9489 0xb60d15 cxx_eval_constant_expression(constexpr_ctx const*, tree_node*, value_cat, bool*, bool*, tree_node**) ../../gcc/cp/constexpr.cc:9770 0xb5c772 cxx_bind_parameters_in_call ../../gcc/cp/constexpr.cc:2913 0xb5c772 cxx_eval_call_expression ../../gcc/cp/constexpr.cc:4234 0xb5fcfd cxx_eval_constant_expression(constexpr_ctx const*, tree_node*, value_cat, bool*, bool*, tree_node**) ../../gcc/cp/constexpr.cc:9352 ``` [0]: https://codeberg.org/bstaletic/gcc/commit/8bacdc8ac390df094c9cec74ca6f717168eb7213 [1]: https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=gcc/testsuite/g%2B%2B.dg/reflect/annotations2.C;h=77b581165f14ddffbba51275caa0b5810d680075;hb=HEAD#l33 [2]: https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=gcc/testsuite/g%2B%2B.dg/reflect/annotations3.C;h=1f80d7a1851298bc931b89db163711c5a29a3ab9;hb=HEAD#l147 [3]: https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=gcc/cp/pt.cc;h=ddf492b34354ec1aa398cd945162378a09ac570e;hb=b95955b8854ae1e859cc7c87700922924e9a5e5f#l7504 [4]: https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=gcc/testsuite/g%2B%2B.dg/reflect/source_location_of1.C;h=8ba34dbbaa7b93cf9d0ae1441581d099c538840e;hb=HEAD#l42 [5]: https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=gcc/tree.cc;h=d0e745e8d281afce27f8f3f0e25d5b13a5bdc0eb;hb=HEAD#l15000 [6]: https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=gcc/testsuite/g%2B%2B.dg/reflect/source_location_of1.C;h=8ba34dbbaa7b93cf9d0ae1441581d099c538840e;hb=HEAD#l104 [7]: https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=gcc/testsuite/g%2B%2B.dg/reflect/source_location_of1.C;h=8ba34dbbaa7b93cf9d0ae1441581d099c538840e;hb=HEAD#l105 > > Marek > >
