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https://github.com/carbon-language/carbon-lang.git
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Dana Jansens
b22ee48c9b
This disallows building a facet type that contains another facet type with non-extend constraints in it. Which in turn prevents the possibility of introducing a different `.Self` into a facet type. Eval can still insert a facet type with non-extend constraints, as we only prevent it for `where` being written into the facet type. There is a TODO in handle_where.cpp for this and some tests in toolchain/check/testdata/facet/nested_facet_types_from_eval.carbon
62 lines
2.3 KiB
Plaintext
62 lines
2.3 KiB
Plaintext
// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
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// Exceptions. See /LICENSE for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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// INCLUDE-FILE: toolchain/testing/testdata/min_prelude/none.carbon
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//
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// AUTOUPDATE
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// TIP: To test this file alone, run:
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// TIP: bazel test //toolchain/testing:file_test --test_arg=--file_tests=toolchain/check/testdata/impl/lookup/access.carbon
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// TIP: To dump output, run:
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// TIP: bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/check/testdata/impl/lookup/access.carbon
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// --- fail_todo_impl_witness_access_in_impl_type_structure.carbon
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library "[[@TEST_NAME]]";
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interface X(T:! type) {}
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interface Y {
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let Y1:! type;
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}
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interface Z {
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let Z1:! type;
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}
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// There's 2 ImplWitnessAccess instructions in the type, but they together
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// resolve to a symbolic type value, so the type structure is: `? as X(?)`
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impl forall [T:! Z where .Z1 impls Y] T as X(T.Z1.(Y.Y1)) {}
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class C(W:! type) {
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impl as Y where .Y1 = W {}
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}
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fn F(V:! Z where .Z1 = C({})) {
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// The type stucture is `? as X({})` which will match the impl's less specific
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// `? as X(?)`, then the impl will deduce the parameter of `X` to be `{}` from
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// the type of `V`. This would fail if ImplWitnessAccess instructions were
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// treated as Concrete in the type structure, since the impl would have a
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// different concrete value (an ImplWitnessAccess) than the query (a
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// StructValue).
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V as X({});
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}
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fn G(V:! Z where .Z1 impls Y) {
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// The type structure is `? as X(?)`, also built from ImplWitnessAccess insts,
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// which will match the impl's `? as X(?)`.
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V as X(V.(Z.Z1).(Y.Y1));
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}
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fn H(U:! type, V:! Z where .Z1 = C(U)) {
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// The type structure is `? as X(?)`, without using an ImplWitnessAccess,
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// which will match the impl's `? as X(?)`. This would fail if
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// ImplWitnessAccess instructions were treated as Concrete in the type
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// structure, since the impl's type structure would be more specific than the
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// query's.
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//
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// TODO: This should pass.
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// CHECK:STDERR: fail_todo_impl_witness_access_in_impl_type_structure.carbon:[[@LINE+4]]:3: error: cannot convert type `V` that implements `Z where .(Z.Z1) = C(U)` into type implementing `X(U)` [ConversionFailureFacetToFacet]
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// CHECK:STDERR: V as X(U);
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// CHECK:STDERR: ^~~~~~~~~
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// CHECK:STDERR:
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V as X(U);
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}
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