Merge pull request #80190 from DougGregor/conformance-isolation-diagnostics

Rework diagnostics for conformance isolation failures

Author: DougGregor

include/swift/AST/ASTContextGlobalCache.h

@@ -18,17 +18,71 @@
 //===----------------------------------------------------------------------===//
 
 #include "swift/AST/ASTContext.h"
+#include "swift/AST/ActorIsolation.h"
+#include <variant>
 
 namespace swift {
 
+class NormalProtocolConformance;
+class ValueDecl;
+
+/// Describes an isolation error where the witness has actor isolation that
+/// conflicts with the requirement's expectation.
+struct WitnessIsolationError {
+  /// The requirement declaration.
+  ValueDecl *requirement;
+
+  /// The witness.
+  ValueDecl *witness;
+
+  /// The pre-Swift-6 diagnostic behavior.
+  DiagnosticBehavior behavior;
+
+  /// Whether the witness is missing "distributed".
+  bool isMissingDistributed;
+
+  /// The isolation of the requirement, mapped into the conformance.
+  ActorIsolation requirementIsolation;
+
+  /// The isolation domain that the witness would need to go into for it
+  /// to be suitable for the requirement.
+  ActorIsolation referenceIsolation;
+
+  /// Diagnose this witness isolation error.
+  void diagnose(const NormalProtocolConformance *conformance) const;
+};
+
+/// Describes an isolation error involving an associated conformance.
+struct AssociatedConformanceIsolationError {
+  ProtocolConformance *isolatedConformance;
+
+  /// Diagnose this associated conformance isolation error.
+  void diagnose(const NormalProtocolConformance *conformance) const;
+};
+
+/// Describes an isolation error that occurred during conformance checking.
+using ConformanceIsolationError = std::variant<
+    WitnessIsolationError, AssociatedConformanceIsolationError>;
+
 /// A collection of side tables associated with the ASTContext itself, meant
-// as
+/// as a way to keep sparse information out of the AST nodes themselves and
+/// not require one to touch ASTContext.h to add such information.
 struct ASTContext::GlobalCache {
   /// Mapping from normal protocol conformances to the explicitly-specified
   /// global actor isolations, e.g., when the conformance was spelled
   /// `@MainActor P` or similar.
   llvm::DenseMap<const NormalProtocolConformance *, TypeExpr *>
       conformanceExplicitGlobalActorIsolation;
+
+  /// Mapping from normal protocol conformances to the set of actor isolation
+  /// problems that occur within the conformances.
+  ///
+  /// This map will be empty for well-formed code, and is used to accumulate
+  /// information so that the diagnostics can be coalesced.
+  llvm::DenseMap<
+    const NormalProtocolConformance *,
+    std::vector<ConformanceIsolationError>
+  > conformanceIsolationErrors;
 };
 
 } // end namespace 

include/swift/AST/DiagnosticsSema.def

@@ -42,8 +42,6 @@ NOTE(opaque_return_type_declared_here,none,
      "opaque return type declared here", ())
 NOTE(default_value_declared_here,none,
      "default value declared here", ())
-NOTE(protocol_requirement_declared_here,none,
-     "requirement %0 declared here", (const ValueDecl *))
 
 //------------------------------------------------------------------------------
 // MARK: Constraint solver diagnostics
@@ -2743,8 +2741,6 @@ WARNING(add_predates_concurrency_import,none,
 GROUPED_WARNING(remove_predates_concurrency_import,PreconcurrencyImport,
                 DefaultIgnore,
                 "'@preconcurrency' attribute on module %0 has no effect", (Identifier))
-NOTE(add_preconcurrency_to_conformance,none,
-     "add '@preconcurrency' to the %0 conformance to defer isolation checking to run time", (DeclName))
 WARNING(remove_public_import,none,
         "public import of %0 was not used in public declarations or inlinable code",
         (Identifier))
@@ -5444,15 +5440,7 @@ ERROR(async_in_nonasync_function,none,
       (unsigned, bool))
 NOTE(note_add_async_to_function,none,
      "add 'async' to function %0 to make it asynchronous", (const ValueDecl *))
-NOTE(note_add_nonisolated_to_decl,none,
-     "add 'nonisolated' to %0 to make this %kindonly0 not isolated to the actor",
-     (const ValueDecl *))
-NOTE(note_add_async_and_throws_to_decl,none,
-     "mark the protocol requirement %0 '%select{|async|throws|async throws}1' "
-     "to allow actor-isolated conformances",
-     (const ValueDecl *, unsigned))
-NOTE(note_add_distributed_to_decl,none,
-     "add 'distributed' to %0 to make this %kindonly0 satisfy the protocol requirement",
+NOTE(note_non_distributed,none, "non-distributed %kind0",
      (const ValueDecl *))
 ERROR(invalid_isolated_calls_in_body,none,
      "calls to '@%0'-isolated' code in %kind1",
@@ -5684,6 +5672,11 @@ ERROR(distributed_actor_func_unsupported_specifier, none,
 ERROR(distributed_actor_func_variadic, none,
       "cannot declare variadic argument %0 in %kind1",
       (DeclName, const ValueDecl *))
+ERROR(conformance_missing_distributed,none,
+      "conformance of %0 to distributed %kind1 uses non-distributed operations",
+      (Type, const ValueDecl *))
+NOTE(note_add_distributed_multi,none,
+     "mark all declarations used in the conformance 'distributed'", ())
 NOTE(actor_mutable_state,none,
      "mutation of this %0 is only permitted within the actor",
      (DescriptiveDeclKind))
@@ -5702,16 +5695,26 @@ NOTE(shared_state_make_immutable,none,
      (const ValueDecl *))
 NOTE(shared_state_nonisolated_unsafe,none,
      "disable concurrency-safety checks if accesses are protected by an external synchronization mechanism", (const ValueDecl *))
-ERROR(actor_isolated_witness,none,
-     "%select{|distributed }0%1 %kind2 cannot be used to satisfy %3 "
-     "requirement from protocol %base4",
-     (bool, ActorIsolation, const ValueDecl *, ActorIsolation,
-      const ValueDecl *))
+NOTE(note_actor_isolated_witness,none,
+     "%0 %kind1 cannot satisfy %2 requirement",
+     (ActorIsolation, const ValueDecl *, ActorIsolation))
 ERROR(actor_cannot_conform_to_global_actor_protocol,none,
       "actor %0 cannot conform to global actor isolated protocol %1",
       (Type, Type))
 NOTE(protocol_isolated_to_global_actor_here,none,
      "%0 is isolated to global actor %1 here", (Type, Type))
+ERROR(conformance_mismatched_isolation,none,
+      "conformance of %0 to %kind1 involves isolation mismatches "
+      "and can cause data races",
+      (Type, const ValueDecl *))
+ERROR(conformance_mismatched_isolation_common,none,
+      "conformance of %0 to %kind1 crosses into %2 code and can cause "
+      "data races", (Type, const ValueDecl *, ActorIsolation))
+NOTE(note_make_conformance_preconcurrency,none,
+     "turn data races into runtime errors with '@preconcurrency'",
+     ())
+NOTE(note_make_witnesses_nonisolated,none,
+     "mark all declarations used in the conformance 'nonisolated'", ())
 
 ERROR(isolated_parameter_not_actor,none,
       "'isolated' parameter type %0 does not conform to 'Actor' "
@@ -8369,21 +8372,21 @@ ERROR(attr_abi_incompatible_with_silgen_name,none,
 ERROR(isolated_conformance_experimental_feature,none,
       "isolated conformances require experimental feature "
       " 'IsolatedConformances'", ())
+NOTE(note_isolate_conformance_to_global_actor,none,
+     "isolate this conformance to the %select{global actor %0|main actor}1 "
+     "with '@%2'", (Type, bool, StringRef))
+NOTE(note_depends_on_isolated_conformance,none,
+     "conformance depends on %0 conformance of %1 to %kind2",
+     (ActorIsolation, Type, const ValueDecl *))
 ERROR(nonisolated_conformance_depends_on_isolated_conformance,none,
       "conformance of %0 to %1 depends on %2 conformance of %3 to %4; mark it as '%5'",
       (Type, DeclName, ActorIsolation, Type, DeclName, StringRef))
-ERROR(isolated_conformance_mismatch_with_associated_isolation,none,
-      "%0 conformance of %1 to %2 cannot depend on %3 conformance of %4 to %5",
-      (ActorIsolation, Type, DeclName, ActorIsolation, Type, DeclName))
-NOTE(add_isolated_to_conformance,none,
-     "add '%0' to the %1 conformance to restrict it to %2 code",
-    (StringRef, DeclName, ActorIsolation))
 ERROR(isolated_conformance_with_sendable,none,
-      "%4 conformance of %0 to %1 cannot be used to satisfy conformance "
+      "%4 conformance of %0 to %1 cannot satisfy conformance "
       "requirement for a %select{`Sendable`|`SendableMetatype`}2 type "
       "parameter %3", (Type, DeclName, bool, Type, ActorIsolation))
 ERROR(isolated_conformance_with_sendable_simple,none,
-      "%2 conformance of %0 to %1 cannot be used to satisfy "
+      "%2 conformance of %0 to %1 cannot satisfy "
       "conformance requirement for a `Sendable` type parameter ",
       (Type, DeclName, ActorIsolation))
 ERROR(isolated_conformance_wrong_domain,none,

include/swift/AST/EducationalNotes.def

@@ -107,4 +107,9 @@ EDUCATIONAL_NOTES(actor_isolated_call_decl,
 EDUCATIONAL_NOTES(error_in_swift_lang_mode,
                   "error-in-future-swift-version.md")
 
+EDUCATIONAL_NOTES(conformance_mismatched_isolation,
+                  "conformance-isolation.md")
+EDUCATIONAL_NOTES(conformance_mismatched_isolation_common,
+                  "conformance-isolation.md")
+
 #undef EDUCATIONAL_NOTES