mirror of
https://github.com/carbon-language/carbon-lang.git
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Dana Jansens
f51c075f8b
Point symbolic witnesses into `.Self` written inside an impl decl at the impl that is being declared. This is tricky because the impl does not yet exist. So we use a new instruction `ImplSelfWitness` which _will_ be replaced by the `ImplWitness` once it becomes available. The `ImplSelfWitness` acts like a symbolic witness, except it does not perform lookup, since we know which impl we will get a witness from. This prevents us from finding other impls when performing lookups into `.Self` in an impl decl, which produces incorrect/incoherent results.
302 lines
11 KiB
Plaintext
302 lines
11 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/int.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/rewrites.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/rewrites.carbon
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// --- rewrite_in_facet_type_before.carbon
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library "[[@TEST_NAME]]";
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interface I { let X: type; }
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interface J {}
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impl () as J {}
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// This uses the earlier rewrite to see that we need `() impls J`.
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impl forall [T: type] T as I where .X = () and .X impls J {}
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// --- fail_rewrite_in_facet_type_before_missing_impl.carbon
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library "[[@TEST_NAME]]";
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interface I { let X: type; }
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interface J {}
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// .X does not impl J.
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// CHECK:STDERR: fail_rewrite_in_facet_type_before_missing_impl.carbon:[[@LINE+4]]:1: error: constraint `I where () impls J and .(I.X) = ()` being implemented requires that `()` implements `J` [IdentifiedRequireImplsNotImplemented]
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// CHECK:STDERR: impl forall [T: type] T as I where .X = () and .X impls J {}
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// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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// CHECK:STDERR:
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impl forall [T: type] T as I where .X = () and .X impls J {}
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// --- rewrite_in_facet_type_after.carbon
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library "[[@TEST_NAME]]";
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interface I { let X: type; }
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interface J {}
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impl () as J {}
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// We don't see the rewrite until later, but when we look at the constraints
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// required, we still need to see that we need `() impls J`.
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impl forall [T: type] T as I where .X impls J and .X = () {}
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// --- fail_rewrite_in_facet_type_after_missing_impl.carbon
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library "[[@TEST_NAME]]";
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interface I { let X: type; }
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interface J {}
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// .X does not impl J.
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// CHECK:STDERR: fail_rewrite_in_facet_type_after_missing_impl.carbon:[[@LINE+4]]:1: error: constraint `I where .(I.X) impls J and .(I.X) = ()` being implemented requires that `()` implements `J` [IdentifiedRequireImplsNotImplemented]
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// CHECK:STDERR: impl forall [T: type] T as I where .X impls J and .X = () {}
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// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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// CHECK:STDERR:
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impl forall [T: type] T as I where .X impls J and .X = () {}
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// --- fail_todo_rewrite_in_named_constraint.carbon
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library "[[@TEST_NAME]]";
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interface I { let X: type; }
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interface J {}
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constraint GivesI {
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extend require impls I where .X = ();
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}
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impl () as J {}
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// The rewrite from `extend` is inherited and should satisfy that `.X impls J`.
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// CHECK:STDERR: fail_todo_rewrite_in_named_constraint.carbon:[[@LINE+7]]:1: error: associated constant X not given a value in impl of interface I [ImplAssociatedConstantNeedsValue]
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// CHECK:STDERR: impl forall [T: type] T as GivesI where .X impls J {}
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// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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// CHECK:STDERR: fail_todo_rewrite_in_named_constraint.carbon:[[@LINE-13]]:19: note: associated constant declared here [AssociatedConstantHere]
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// CHECK:STDERR: interface I { let X: type; }
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// CHECK:STDERR: ^~~~~~~
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// CHECK:STDERR:
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impl forall [T: type] T as GivesI where .X impls J {}
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// --- fail_rewrite_in_named_constraint_missing_impl.carbon
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library "[[@TEST_NAME]]";
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interface I { let X: type; }
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interface J {}
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constraint GivesI {
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extend require impls I where .X = ();
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}
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// .X does not impl J.
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// CHECK:STDERR: fail_rewrite_in_named_constraint_missing_impl.carbon:[[@LINE+7]]:1: error: associated constant X not given a value in impl of interface I [ImplAssociatedConstantNeedsValue]
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// CHECK:STDERR: impl forall [T: type] T as GivesI where .X impls J {}
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// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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// CHECK:STDERR: fail_rewrite_in_named_constraint_missing_impl.carbon:[[@LINE-11]]:19: note: associated constant declared here [AssociatedConstantHere]
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// CHECK:STDERR: interface I { let X: type; }
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// CHECK:STDERR: ^~~~~~~
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// CHECK:STDERR:
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impl forall [T: type] T as GivesI where .X impls J {}
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// --- fail_todo_rewrite_and_impls_in_named_constraint.carbon
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library "[[@TEST_NAME]]";
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interface I { let X: type; }
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interface J {}
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constraint GivesI {
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extend require impls I where .X = ();
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require impls I where .X impls J;
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}
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impl () as J {}
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// The rewrite from `extend` is inherited and should satisfy that `.X impls J`.
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// CHECK:STDERR: fail_todo_rewrite_and_impls_in_named_constraint.carbon:[[@LINE+11]]:1: error: associated constant X not given a value in impl of interface I [ImplAssociatedConstantNeedsValue]
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// CHECK:STDERR: impl forall [T: type] T as GivesI {}
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// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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// CHECK:STDERR: fail_todo_rewrite_and_impls_in_named_constraint.carbon:[[@LINE-14]]:19: note: associated constant declared here [AssociatedConstantHere]
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// CHECK:STDERR: interface I { let X: type; }
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// CHECK:STDERR: ^~~~~~~
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// CHECK:STDERR:
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// CHECK:STDERR: fail_todo_rewrite_and_impls_in_named_constraint.carbon:[[@LINE+4]]:1: error: constraint `GivesI` being implemented requires that `T.(I.X)` implements `J` [IdentifiedRequireImplsNotImplemented]
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// CHECK:STDERR: impl forall [T: type] T as GivesI {}
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// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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// CHECK:STDERR:
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impl forall [T: type] T as GivesI {}
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// --- fail_rewrite_and_impls_in_named_constraint_missing_impl.carbon
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library "[[@TEST_NAME]]";
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interface I { let X: type; }
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interface J {}
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constraint GivesI {
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extend require impls I where .X = ();
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require impls I where .X impls J;
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}
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// .X does not impl J.
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// CHECK:STDERR: fail_rewrite_and_impls_in_named_constraint_missing_impl.carbon:[[@LINE+11]]:1: error: associated constant X not given a value in impl of interface I [ImplAssociatedConstantNeedsValue]
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// CHECK:STDERR: impl forall [T: type] T as GivesI {}
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// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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// CHECK:STDERR: fail_rewrite_and_impls_in_named_constraint_missing_impl.carbon:[[@LINE-12]]:19: note: associated constant declared here [AssociatedConstantHere]
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// CHECK:STDERR: interface I { let X: type; }
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// CHECK:STDERR: ^~~~~~~
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// CHECK:STDERR:
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// CHECK:STDERR: fail_rewrite_and_impls_in_named_constraint_missing_impl.carbon:[[@LINE+4]]:1: error: constraint `GivesI` being implemented requires that `T.(I.X)` implements `J` [IdentifiedRequireImplsNotImplemented]
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// CHECK:STDERR: impl forall [T: type] T as GivesI {}
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// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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// CHECK:STDERR:
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impl forall [T: type] T as GivesI {}
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// --- rewrite_in_facet_type_before_with_generic_param.carbon
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library "[[@TEST_NAME]]";
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interface I { let X: type; }
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interface J(T: type) {}
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impl () as J(()) {}
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// This uses the earlier rewrite to see that we need `() impls J(())`.
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impl forall [T: type] T as I where .X = () and .X impls J(.X) {}
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// --- rewrite_in_facet_type_after_with_generic_param.carbon
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library "[[@TEST_NAME]]";
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interface I { let X: type; }
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interface J(T: type) {}
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impl () as J(()) {}
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// We don't see the rewrite until later, but when we look at the constraints
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// required, we still need to see that we need `() impls J(())`.
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impl forall [T: type] T as I where .X impls J(.X) and .X = () {}
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// --- impl_lookups_in_definition_find_own_impl.carbon
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library "[[@TEST_NAME]]";
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class C {}
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class G(T: type) {}
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interface Z(R: type) {
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let Result: type;
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}
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interface Y(S: type) {}
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impl forall [T: type] () as Y(G(T)) {}
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impl forall [T: type] {} as Y(G(T)) {}
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// This is a blanket impl that overlaps with (but is less specific than)
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// `G(C) as Z(G(C))`, which is the next impl below.
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impl forall [T: type, U: type] G(T) as Z(U) where .Result impls Y(G(T)) and .Result = {} {}
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// The query `G(C) as Z(G(C))` is concrete so any lookups will result in a final
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// witness. The constraint facet type contains `.Result` which causes a lookup
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// for `G(C) as Z(G(C))`. But this lookup occurs before the impl declaration is
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// even completed, so the impl does not yet exist according to check.
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//
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// The naive result is that the lookup finds overlapping impl above, and
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// `.Result` evaluates to `{}` which is incorrect. Then a later query finds this
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// impl and `.Result` evaluates to `()`. We diagnose this a poisoning error,
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// where this impl changes the possible value of `.Result` after a concrete
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// query was made for it.
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//
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// The correct result is for the witness of `G(C) as Z(G(C))` to point to this
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// impl, even though it does not yet exist. No impl lookup should occur for the
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// interface being impl'd from within the declaration. Then `.Result` consistent
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// evalutes to `()`.
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impl G(C) as Z(G(C)) where .Result impls Y(G(C)) and .Result = () {}
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fn F() {
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G(C) as Z(G(C));
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}
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// --- impl_lookups_in_definition_find_own_impl_with_named_constraint.carbon
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library "[[@TEST_NAME]]";
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class C {}
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class G(T: type) {}
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interface Z(R: type) {
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let Result: type;
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}
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interface Y(S: type) {}
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impl forall [T: type] () as Y(G(T)) {}
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impl forall [T: type] {} as Y(G(T)) {}
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impl forall [T: type, U: type] G(T) as Z(U) where .Result impls Y(G(T)) and .Result = {} {}
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constraint N(T: type) {
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extend require impls Z(G(T));
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}
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// See impl_lookups_in_definition_find_own_impl.carbon for an explanation of
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// this test. We are testing the same things, except we put the impl's target
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// interface into a named constraint.
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impl G(C) as N(C) where .Result impls Y(G(C)) and .Result = () {}
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fn F() {
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G(C) as Z(G(C));
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}
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// --- lookup_for_impl_with_period_self_in_constraint.carbon
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library "[[@TEST_NAME]]";
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class C {}
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class G(T: type) {}
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interface Z(R: type) {
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let Result: type;
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}
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interface Y(S: type) {}
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impl forall [T: type] () as Y(G(T)) {}
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// We don't want `.Self` references to escape the `impl` decl, so this tests a
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// scenario where they used to escape and cause an infinite cycle.
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//
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// The impl lookup in `F()` finds this impl, which has a `.Self` in its set of
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// constraints (in `.Result impls ...`). The lookup operation can't identify the
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// constraint and replace `.Self` without creating a new witness that causes a
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// lookup for this impl again.
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impl forall [T: type, U: type] G(T) as Z(U) where .Result impls Y(G(T)) and .Result = () {}
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fn F() {
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G(C) as Z(G(C));
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}
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// --- where_that_does_not_constrain_impl.carbon
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library "[[@TEST_NAME]]";
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interface Z {
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let Z1: type;
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}
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interface Y(T: type) {}
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interface Tuple {}
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impl () as Tuple {}
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// This test puts a `where` expression in two problematic places:
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// - The `where` in the generic constraint for the impl should _not_ refer to
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// the impl. It should have a non-final witness for the `.Z1` access.
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// - The `where` in the generic argument to `Y` does not constrain the impl's
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// self type so the access `.Z1` should also have a symbolic witness, not a
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// witness for the impl itself.
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//
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// If done incorrectly, either of the above may become a witness for the impl
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// itself, which is incorrect and results in a lookup into an empty witness
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// table (for `Y`) when looking for `.Z1`.
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//
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// Also if done incorrectly, we may declare that lookups in `Z` are for the
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// current impl, because of the `Z where ...` in the argument for `Y` if we
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// mistake that as being `impl as Z where ...`. That would result in the later
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// access `.Self.(Z.Z1)` becoming a witness for the impl itself, which would try
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// to find a value for `.Z1` in the empty witness table for `Y`.
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impl forall [T: Z where .Z1 = ()] T as Y(Z where .Z1 = ())
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where .Self impls Z and .Self.(Z.Z1) impls Tuple {}
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