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Chandler Carruth
8be274cf60
Implement the toolchain side of proposal #7254, removing the `:!` binding syntax for generic and template parameters in favor of the keywords `generic`, `template`, and `runtime` plus contextual defaults for phase. For valid programs this is semantics-preserving: each binding resolves to the same phase, and produces the same SemIR, as it did under `:!`/`:`. The parser derives a binding's phase from its syntactic context plus any explicit phase keyword; new diagnostics and error recovery for misused keywords are described below. Implementation details for each component: - Lexer: remove the `:!` (`ColonExclaim`) token, move its virtual parse-node budget onto `:`, and add the `generic` and `runtime` keywords. - Parser: thread a `BindingContext` (`ExplicitParam`, `DeducedParam`, or `CompileTimeEntityParam`) from declaration introducers down through parameter lists to each binding pattern, using a one-token lookahead to distinguish a name-qualifier parameter list from a declaration's own final list. Parameters of a compile-time entity (`class`, `interface`, `constraint`, `choice`, `alias`, `export`, `namespace`) and deduced `[]` parameters default to checked generic; explicit function parameters and local bindings default to runtime. `HandleBindingPattern` resolves the phase from that context plus the keyword: a `generic` keyword needs no node of its own (the phase is carried by the binding's node kind), while a `runtime` keyword is preserved as a `RuntimeBindingName` node so `check` can name it in a diagnostic. A phase keyword that is merely redundant with the contextual default is diagnosed here, without invalidating the parse tree. - Check: a phase keyword that is invalid for its context (for example `runtime` on a checked-generic parameter) is diagnosed here, and recovers by building an error binding that still introduces the name so that later uses of it do not produce cascading errors. The removed `:!` syntax is now rejected as an ordinary parse error. The `form`/`:?`/`->?` ("extended types") portion of proposal #7254 is left for a separate change. Assisted-by: Claude Code
192 lines
7.2 KiB
Plaintext
192 lines
7.2 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/convert.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/specialization_poison.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/specialization_poison.carbon
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// --- fail_final_poisoned_concrete_query_in_specific.carbon
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library "[[@TEST_NAME]]";
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interface I {
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let T: type;
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fn F(self) -> T;
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}
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impl forall [U: type] U as I where .T = () {
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fn F(unused self) -> () { return (); }
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}
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// CHECK:STDERR: fail_final_poisoned_concrete_query_in_specific.carbon:[[@LINE+3]]:24: error: found `impl` that would change the result of an earlier use of `C* as I` [PoisonedImplLookupConcreteResult]
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// CHECK:STDERR: fn H[W: type](v: W) -> W.(I.T) {
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// CHECK:STDERR: ^~~~~~~
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fn H[W: type](v: W) -> W.(I.T) {
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return v.(I.F)();
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}
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class C { adapt (); }
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fn G(p: C*) -> () {
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// This concrete impl lookup query poisons any further specializations.
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return H(p);
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}
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// CHECK:STDERR: fail_final_poisoned_concrete_query_in_specific.carbon:[[@LINE+7]]:1: note: the use would select the `impl` here but it was not found yet [PoisonedImplLookupConcreteResultNoteBadImpl]
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// CHECK:STDERR: impl C* as I where .T = C {
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// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~~
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// CHECK:STDERR: fail_final_poisoned_concrete_query_in_specific.carbon:[[@LINE-21]]:1: note: the use had selected the `impl` here [PoisonedImplLookupConcreteResultNotePreviousImpl]
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// CHECK:STDERR: impl forall [U: type] U as I where .T = () {
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// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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// CHECK:STDERR:
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impl C* as I where .T = C {
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fn F(self) -> C { return *self; }
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}
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// --- fail_final_poisoned_concrete_query_in_generic.carbon
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library "[[@TEST_NAME]]";
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interface I {
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let T: type;
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}
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impl forall [U: type] U as I where .T = () {}
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class C {}
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fn H[W: type](unused v: W) {
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// This concrete impl lookup query poisons any further specializations.
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// CHECK:STDERR: fail_final_poisoned_concrete_query_in_generic.carbon:[[@LINE+3]]:17: error: found `impl` that would change the result of an earlier use of `C as I` [PoisonedImplLookupConcreteResult]
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// CHECK:STDERR: let unused a: C.(I.T) = ();
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// CHECK:STDERR: ^~~~~~~
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let unused a: C.(I.T) = ();
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}
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// CHECK:STDERR: fail_final_poisoned_concrete_query_in_generic.carbon:[[@LINE+7]]:1: note: the use would select the `impl` here but it was not found yet [PoisonedImplLookupConcreteResultNoteBadImpl]
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// CHECK:STDERR: impl C as I where .T = C {}
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// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~
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// CHECK:STDERR: fail_final_poisoned_concrete_query_in_generic.carbon:[[@LINE-15]]:1: note: the use had selected the `impl` here [PoisonedImplLookupConcreteResultNotePreviousImpl]
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// CHECK:STDERR: impl forall [U: type] U as I where .T = () {}
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// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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// CHECK:STDERR:
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impl C as I where .T = C {}
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// --- fail_final_poisoned_concrete_query_nested_type_in_self.carbon
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library "[[@TEST_NAME]]";
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interface I {
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let T: type;
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fn F(self) -> T;
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}
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class C(U: type) {}
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impl forall [U: type] C(U) as I where .T = () {
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fn F(unused self) -> () { return (); }
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}
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fn G(c: C(())) -> () {
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// This concrete impl lookup query poisons any further specializations.
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// CHECK:STDERR: fail_final_poisoned_concrete_query_nested_type_in_self.carbon:[[@LINE+3]]:10: error: found `impl` that would change the result of an earlier use of `C(()) as I` [PoisonedImplLookupConcreteResult]
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// CHECK:STDERR: return c.(I.F)();
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// CHECK:STDERR: ^~~~~~~
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return c.(I.F)();
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}
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// CHECK:STDERR: fail_final_poisoned_concrete_query_nested_type_in_self.carbon:[[@LINE+7]]:1: note: the use would select the `impl` here but it was not found yet [PoisonedImplLookupConcreteResultNoteBadImpl]
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// CHECK:STDERR: impl C(()) as I where .T = {} {
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// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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// CHECK:STDERR: fail_final_poisoned_concrete_query_nested_type_in_self.carbon:[[@LINE-15]]:1: note: the use had selected the `impl` here [PoisonedImplLookupConcreteResultNotePreviousImpl]
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// CHECK:STDERR: impl forall [U: type] C(U) as I where .T = () {
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// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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// CHECK:STDERR:
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impl C(()) as I where .T = {} {
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fn F(unused self) -> {} { return {}; }
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}
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// --- fail_final_poisoned_concrete_query_nested_type_in_interface.carbon
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library "[[@TEST_NAME]]";
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interface I(U: type) {
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let T: type;
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fn F(self) -> T;
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}
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impl forall [U: type] U as I(U) where .T = () {
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fn F(unused self) -> () { return (); }
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}
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class C {}
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fn G(c: C) -> () {
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// This concrete impl lookup query poisons any further specializations.
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// CHECK:STDERR: fail_final_poisoned_concrete_query_nested_type_in_interface.carbon:[[@LINE+3]]:10: error: found `impl` that would change the result of an earlier use of `C as I(C)` [PoisonedImplLookupConcreteResult]
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// CHECK:STDERR: return c.(I(C).F)();
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// CHECK:STDERR: ^~~~~~~~~~
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return c.(I(C).F)();
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}
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// CHECK:STDERR: fail_final_poisoned_concrete_query_nested_type_in_interface.carbon:[[@LINE+7]]:1: note: the use would select the `impl` here but it was not found yet [PoisonedImplLookupConcreteResultNoteBadImpl]
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// CHECK:STDERR: impl C as I(C) where .T = {} {
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// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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// CHECK:STDERR: fail_final_poisoned_concrete_query_nested_type_in_interface.carbon:[[@LINE-17]]:1: note: the use had selected the `impl` here [PoisonedImplLookupConcreteResultNotePreviousImpl]
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// CHECK:STDERR: impl forall [U: type] U as I(U) where .T = () {
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// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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// CHECK:STDERR:
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impl C as I(C) where .T = {} {
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fn F(unused self) -> {} { return {}; }
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}
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// --- todo_fail_final_poisoned_by_generic_query.carbon
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library "[[@TEST_NAME]]";
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interface I {
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let T: type;
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fn F(self) -> T;
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}
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impl forall [U: type] U as I where .T = () {
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fn F(unused self) -> () { return (); }
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}
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fn H[W: type](v: W) -> W.(I.T) {
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return v.(I.F)();
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}
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// This function could return a concrete `X` if it saw the `final` impl below.
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fn G[X: type](p: X*) -> (X*).(I.T) {
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return H(p);
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}
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// TODO: This should be diagnosed as poisoned, as H() uses an associated
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// constant from the `impl` which was treated as a symbolic, but this would
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// change it to be a concrete type.
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final impl forall [V: Core.Copy] V* as I where .T = V {
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fn F(self) -> V { return *self; }
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}
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// --- fail_todo_poisoned_concrete_lookup_from_eval_fn.carbon
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library "[[@TEST_NAME]]";
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fn F() {
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class D {}
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// CHECK:STDERR: fail_todo_poisoned_concrete_lookup_from_eval_fn.carbon:[[@LINE+4]]:22: error: semantics TODO: `HandleAutoTypeLiteral` [SemanticsTodo]
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// CHECK:STDERR: musteval fn G() -> auto {
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// CHECK:STDERR: ^~~~
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// CHECK:STDERR:
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musteval fn G() -> auto {
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class C(T: type) {}
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impl forall [T: type] C(T) as Z {}
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C(D) as Z;
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return C(D);
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}
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// TODO: error: found `impl` that would change the result of an earlier use of `C(D) as Z`.
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impl G() as Z {}
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}
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