Support associated constants in impl witnesses (#4770)

With this change, we now support impl of interfaces with non-function associated constants. Also: * Make impl diagnostics use more consistent names * Make some impl tests "no_prelude" Still to do: * Facet type resolution as a separate, reusable step * Using the assigned values of associated constants (see `fail_todo_use_assoc_const.carbon`) --------- Co-authored-by: Josh L <[email protected]> Co-authored-by: Richard Smith <[email protected]>
carbon-language · Jan 11, 2025 · 230a8ee · 230a8ee
1 parent fb1a9ba
commit 230a8ee
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Showing 20 changed files with 1,828 additions and 198 deletions.
diff --git a/toolchain/check/check_unit.cpp b/toolchain/check/check_unit.cpp
@@ -402,9 +402,9 @@ auto CheckUnit::CheckRequiredDefinitions() -> void {
         auto& impl = context_.impls().Get(impl_decl.impl_id);
         if (!impl.is_defined()) {
           FillImplWitnessWithErrors(context_, impl);
-          CARBON_DIAGNOSTIC(MissingImplDefinition, Error,
+          CARBON_DIAGNOSTIC(ImplMissingDefinition, Error,
                             "impl declared but not defined");
-          emitter_.Emit(decl_inst_id, MissingImplDefinition);
+          emitter_.Emit(decl_inst_id, ImplMissingDefinition);
         }
         break;
       }

diff --git a/toolchain/check/handle_impl.cpp b/toolchain/check/handle_impl.cpp
@@ -321,7 +321,8 @@ static auto BuildImplDecl(Context& context, Parse::AnyImplDeclId node_id,
   // TODO: Check that its constant value is a constraint.
   auto [constraint_inst_id, constraint_type_id] =
       ExprAsType(context, constraint_node, constraint_id);
-  // TODO: Do facet type resolution here.
+  // TODO: Do facet type resolution here, and enforce that the constraint
+  // extends a single interface.
   // TODO: Determine `interface_id` and `specific_id` once and save it in the
   // resolved facet type, instead of in multiple functions called below.
   // TODO: Skip work below if facet type resolution fails, so we don't have a
@@ -373,12 +374,16 @@ static auto BuildImplDecl(Context& context, Parse::AnyImplDeclId node_id,
   if (!impl_decl.impl_id.is_valid()) {
     impl_info.generic_id = BuildGeneric(context, impl_decl_id);
     impl_info.witness_id = ImplWitnessForDeclaration(context, impl_info);
+    AddConstantsToImplWitnessFromConstraint(
+        context, impl_info, impl_info.witness_id, impl_decl.impl_id);
     FinishGenericDecl(context, impl_decl_id, impl_info.generic_id);
     impl_decl.impl_id = context.impls().Add(impl_info);
     lookup_bucket_ref.push_back(impl_decl.impl_id);
   } else {
-    FinishGenericRedecl(context, impl_decl_id,
-                        context.impls().Get(impl_decl.impl_id).generic_id);
+    const auto& first_impl = context.impls().Get(impl_decl.impl_id);
+    AddConstantsToImplWitnessFromConstraint(
+        context, impl_info, first_impl.witness_id, impl_decl.impl_id);
+    FinishGenericRedecl(context, impl_decl_id, first_impl.generic_id);
   }
 
   // Write the impl ID into the ImplDecl.

diff --git a/toolchain/check/impl.cpp b/toolchain/check/impl.cpp
diff --git a/toolchain/check/impl.h b/toolchain/check/impl.h
@@ -14,7 +14,11 @@ namespace Carbon::Check {
 auto ImplWitnessForDeclaration(Context& context, const SemIR::Impl& impl)
     -> SemIR::InstId;
 
-// TODO: AddConstantsToImplWitnessFromConstraint()
+auto AddConstantsToImplWitnessFromConstraint(Context& context,
+                                             const SemIR::Impl& impl,
+                                             SemIR::InstId witness_id,
+                                             SemIR::ImplId prev_decl_id)
+    -> void;
 
 // Update `impl`'s witness at the start of a definition.
 auto ImplWitnessStartDefinition(Context& context, SemIR::Impl& impl) -> void;

diff --git a/toolchain/check/testdata/impl/fail_extend_impl_type_as.carbon b/toolchain/check/testdata/impl/fail_extend_impl_type_as.carbon
@@ -37,7 +37,7 @@ class E {
   // CHECK:STDERR:   extend impl Self as I {}
   // CHECK:STDERR:               ^~~~
   // CHECK:STDERR:
-  // CHECK:STDERR: fail_extend_impl_type_as.carbon:[[@LINE-11]]:3: error: impl declared but not defined [MissingImplDefinition]
+  // CHECK:STDERR: fail_extend_impl_type_as.carbon:[[@LINE-11]]:3: error: impl declared but not defined [ImplMissingDefinition]
   // CHECK:STDERR:   extend impl D as I;
   // CHECK:STDERR:   ^~~~~~~~~~~~~~~~~~~
   extend impl Self as I {}

diff --git a/toolchain/check/testdata/impl/fail_extend_non_interface.carbon b/toolchain/check/testdata/impl/fail_extend_non_interface.carbon
@@ -17,7 +17,7 @@ class C {
   // CHECK:STDERR:   extend impl as i32;
   // CHECK:STDERR:   ^~~~~~~~~~~~~~~~~~~
   // CHECK:STDERR:
-  // CHECK:STDERR: fail_extend_non_interface.carbon:[[@LINE+3]]:3: error: impl declared but not defined [MissingImplDefinition]
+  // CHECK:STDERR: fail_extend_non_interface.carbon:[[@LINE+3]]:3: error: impl declared but not defined [ImplMissingDefinition]
   // CHECK:STDERR:   extend impl as i32;
   // CHECK:STDERR:   ^~~~~~~~~~~~~~~~~~~
   extend impl as i32;

diff --git a/toolchain/check/testdata/impl/fail_extend_partially_defined_interface.carbon b/toolchain/check/testdata/impl/fail_extend_partially_defined_interface.carbon
@@ -17,7 +17,7 @@ interface I {
     // CHECK:STDERR: interface I {
     // CHECK:STDERR: ^~~~~~~~~~~~~
     // CHECK:STDERR:
-    // CHECK:STDERR: fail_extend_partially_defined_interface.carbon:[[@LINE+3]]:5: error: impl declared but not defined [MissingImplDefinition]
+    // CHECK:STDERR: fail_extend_partially_defined_interface.carbon:[[@LINE+3]]:5: error: impl declared but not defined [ImplMissingDefinition]
     // CHECK:STDERR:     extend impl as I;
     // CHECK:STDERR:     ^~~~~~~~~~~~~~~~~
     extend impl as I;

diff --git a/toolchain/check/testdata/impl/fail_extend_undefined_interface.carbon b/toolchain/check/testdata/impl/fail_extend_undefined_interface.carbon
@@ -43,7 +43,7 @@ fn F(c: C) {
   // CHECK:STDERR:   extend impl as I;
   // CHECK:STDERR:                  ^
   // CHECK:STDERR:
-  // CHECK:STDERR: fail_extend_undefined_interface.carbon:[[@LINE-25]]:3: error: impl declared but not defined [MissingImplDefinition]
+  // CHECK:STDERR: fail_extend_undefined_interface.carbon:[[@LINE-25]]:3: error: impl declared but not defined [ImplMissingDefinition]
   // CHECK:STDERR:   extend impl as I;
   // CHECK:STDERR:   ^~~~~~~~~~~~~~~~~
   c.F();

diff --git a/toolchain/check/testdata/impl/fail_impl_bad_assoc_fn.carbon b/toolchain/check/testdata/impl/fail_impl_bad_assoc_fn.carbon
@@ -14,7 +14,7 @@ class NoF {
   // CHECK:STDERR: fail_impl_bad_assoc_fn.carbon:[[@LINE+7]]:3: error: missing implementation of F in impl of interface I [ImplMissingFunction]
   // CHECK:STDERR:   impl as I {}
   // CHECK:STDERR:   ^~~~~~~~~~~
-  // CHECK:STDERR: fail_impl_bad_assoc_fn.carbon:[[@LINE-6]]:15: note: associated function F declared here [ImplAssociatedFunctionHere]
+  // CHECK:STDERR: fail_impl_bad_assoc_fn.carbon:[[@LINE-6]]:15: note: associated function F declared here [AssociatedFunctionHere]
   // CHECK:STDERR: interface I { fn F(); }
   // CHECK:STDERR:               ^~~~~~~
   // CHECK:STDERR:
@@ -26,7 +26,7 @@ class FNotFunction {
     // CHECK:STDERR: fail_impl_bad_assoc_fn.carbon:[[@LINE+7]]:5: error: associated function F implemented by non-function [ImplFunctionWithNonFunction]
     // CHECK:STDERR:     class F;
     // CHECK:STDERR:     ^~~~~~~~
-    // CHECK:STDERR: fail_impl_bad_assoc_fn.carbon:[[@LINE-18]]:15: note: associated function F declared here [ImplAssociatedFunctionHere]
+    // CHECK:STDERR: fail_impl_bad_assoc_fn.carbon:[[@LINE-18]]:15: note: associated function F declared here [AssociatedFunctionHere]
     // CHECK:STDERR: interface I { fn F(); }
     // CHECK:STDERR:               ^~~~~~~
     // CHECK:STDERR:
@@ -42,7 +42,7 @@ class FAlias {
     // CHECK:STDERR: fail_impl_bad_assoc_fn.carbon:[[@LINE+7]]:11: error: associated function F implemented by non-function [ImplFunctionWithNonFunction]
     // CHECK:STDERR:     alias F = PossiblyF;
     // CHECK:STDERR:           ^
-    // CHECK:STDERR: fail_impl_bad_assoc_fn.carbon:[[@LINE-34]]:15: note: associated function F declared here [ImplAssociatedFunctionHere]
+    // CHECK:STDERR: fail_impl_bad_assoc_fn.carbon:[[@LINE-34]]:15: note: associated function F declared here [AssociatedFunctionHere]
     // CHECK:STDERR: interface I { fn F(); }
     // CHECK:STDERR:               ^~~~~~~
     // CHECK:STDERR:

diff --git a/toolchain/check/testdata/impl/fail_todo_impl_assoc_const.carbon b/toolchain/check/testdata/impl/fail_todo_impl_assoc_const.carbon