NCGenerics: improve diagnostics

Removing the old, ad-hoc diagnostics code improves the diagnostics we
emit, since the existing diagnostics for missing conformances is already
pretty good.

rdar://127369509

Author: kavon

include/swift/AST/DiagnosticsSema.def

@@ -7811,33 +7811,15 @@ NOTE(noncopyable_parameter_ownership_suggestion, none,
       "add '%0' %1", (StringRef, StringRef))
 ERROR(ownership_specifier_nonescaping_closure,none,
       "'%0' cannot be applied to nonescaping closure", (StringRef))
-ERROR(noncopyable_generics, none,
-      "noncopyable type %0 cannot be used with generics yet",
-      (Type))
 ERROR(noncopyable_generics_variadic, none,
       "noncopyable type %0 cannot be used within a variadic type yet",
       (Type))
-ERROR(noncopyable_generics_specific, none,
-      "noncopyable type %0 cannot be used with generic type %1 yet",
-      (Type, Type))
-ERROR(noncopyable_generics_erasure, none,
-      "noncopyable type %0 cannot be erased to copyable existential type %1",
-      (Type, Type))
-ERROR(noncopyable_generics_metatype_cast, none,
-      "metatype %0 cannot be cast to %1 because %2 is noncopyable",
-      (Type, Type, Type))
-ERROR(noncopyable_generics_generic_param, none,
-      "noncopyable type %0 cannot be substituted for copyable %1 %2 in %3",
-      (Type, DescriptiveDeclKind, Type, DeclName))
-ERROR(noncopyable_generics_generic_param_metatype, none,
-      "metatype %4 of noncopyable type %0 cannot be substituted for copyable %1 %2 in %3",
-      (Type, DescriptiveDeclKind, Type, DeclName, Type))
-NOTE(noncopyable_generics_implicit_copyable, none,
-      "%0 %1 has an implicit Copyable requirement",
-      (DescriptiveDeclKind, Type))
-ERROR(noncopyable_element_of_pack_not_supported,none,
-      "parameter pack containing noncopyable element %0 is not supported",
-      (Type))
+NOTE(noncopyable_generics_implicit_conformance_req, none,
+     "'where %noformat0: %noformat1' is implicit here",
+     (Type, Type))
+NOTE(noncopyable_generics_implicit_composition, none,
+     "'%noformat0 & %noformat1' is implicit here",
+     (Type, Type))
 ERROR(noncopyable_effectful_getter,none,
       "%0 of noncopyable type cannot be 'async' or 'throws'", (DescriptiveDeclKind))
 ERROR(noncopyable_enums_do_not_support_indirect,none,

include/swift/Sema/CSFix.h

@@ -432,9 +432,6 @@ enum class FixKind : uint8_t {
   /// vs.`@OtherActor () -> Void`
   AllowGlobalActorMismatch,
 
-  /// Produce an error about a type that must be Copyable
-  MustBeCopyable,
-
   /// Allow 'each' applied to a non-pack type.
   AllowInvalidPackElement,
 
@@ -2139,32 +2136,6 @@ struct NoncopyableMatchFailure {
   }
 };
 
-class MustBeCopyable final : public ConstraintFix {
-  Type noncopyableTy;
-  NoncopyableMatchFailure failure;
-
-  MustBeCopyable(ConstraintSystem &cs,
-                 Type noncopyableTy,
-                 NoncopyableMatchFailure failure,
-                 ConstraintLocator *locator);
-
-public:
-  std::string getName() const override { return "remove move-only from type"; }
-
-  bool diagnose(const Solution &solution, bool asNote = false) const override;
-
-  bool diagnoseForAmbiguity(CommonFixesArray commonFixes) const override;
-
-  static MustBeCopyable *create(ConstraintSystem &cs,
-                             Type noncopyableTy,
-                             NoncopyableMatchFailure failure,
-                             ConstraintLocator *locator);
-
-  static bool classof(const ConstraintFix *fix) {
-    return fix->getKind() == FixKind::MustBeCopyable;
-  }
-};
-
 class AllowInvalidPackElement final : public ConstraintFix {
   Type packElementType;
 

lib/Sema/CSDiagnostics.cpp

@@ -539,6 +539,23 @@ void RequirementFailure::maybeEmitRequirementNote(const Decl *anchor, Type lhs,
     return;
   }
 
+  // If a requirement 'T: InvertibleProtocol' wasn't satisfied, then emit a note
+  // explaining that this requirement was implicit, but is suppressible.
+  if (req.getKind() == RequirementKind::Conformance &&
+      req.getProtocolDecl()->getInvertibleProtocolKind() &&
+      req.getFirstType()->is<SubstitutableType>()) {
+    auto diag = diag::noncopyable_generics_implicit_conformance_req;
+
+    // Handle 'some X' where the '& InvertibleProtocol' is implicit
+    if (auto substTy = req.getFirstType()->getAs<GenericTypeParamType>())
+      if (auto gtpd = substTy->getDecl())
+        if (gtpd->isOpaqueType())
+          diag = diag::noncopyable_generics_implicit_composition;
+
+    emitDiagnosticAt(anchor, diag, req.getFirstType(), req.getSecondType());
+    return;
+  }
+
   if (req.getKind() == RequirementKind::Layout ||
       rhs->isEqual(req.getSecondType())) {
     // If the note is tautological, bail out.
@@ -637,20 +654,6 @@ bool MissingConformanceFailure::diagnoseAsError() {
   if (diagnoseAsAmbiguousOperatorRef())
     return true;
 
-  // Use tailored diagnostics for failure to conform to Copyable.
-  if (auto asProtoType = protocolType->getAs<ProtocolType>()) {
-    if (auto *protoDecl = asProtoType->getDecl()) {
-      if (protoDecl->isSpecificProtocol(KnownProtocolKind::Copyable)) {
-        NotCopyableFailure failure(getSolution(),
-                                   nonConformingType,
-                                   NoncopyableMatchFailure::forCopyableConstraint(),
-                                   getLocator());
-        if (failure.diagnoseAsError())
-          return true;
-      }
-    }
-  }
-
   if (nonConformingType->isObjCExistentialType()) {
     emitDiagnostic(diag::protocol_does_not_conform_static, nonConformingType,
                    protocolType);
@@ -6348,111 +6351,6 @@ bool NotCompileTimeConstFailure::diagnoseAsError() {
   return true;
 }
 
-bool NotCopyableFailure::diagnoseAsError() {
-  switch (failure.getKind()) {
-  case NoncopyableMatchFailure::ExistentialCast: {
-    if (noncopyableTy->is<AnyMetatypeType>())
-      emitDiagnostic(diag::noncopyable_generics_metatype_cast,
-                     noncopyableTy,
-                     failure.getType(),
-                     noncopyableTy->getMetatypeInstanceType());
-    else
-      emitDiagnostic(diag::noncopyable_generics_erasure,
-                     noncopyableTy,
-                     failure.getType());
-    return true;
-  }
-
-  case NoncopyableMatchFailure::CopyableConstraint: {
-    ConstraintLocator *loc = getLocator();
-    auto path = loc->getPath();
-
-    if (loc->isLastElement<LocatorPathElt::AnyTupleElement>()) {
-      assert(!noncopyableTy->is<TupleType>() && "will use poor wording");
-      emitDiagnostic(diag::tuple_move_only_not_supported, noncopyableTy);
-      return true;
-    }
-
-    if (loc->isLastElement<LocatorPathElt::PackElement>()) {
-      emitDiagnostic(diag::noncopyable_element_of_pack_not_supported,
-                     noncopyableTy);
-      return true;
-    }
-
-    auto diagnoseGenericTypeParamType = [&](GenericTypeParamType *typeParam) {
-      if (!typeParam)
-        return false;
-
-      if (auto *paramDecl = typeParam->getDecl()) {
-        if (auto *owningDecl =
-            dyn_cast_or_null<ValueDecl>(paramDecl->getDeclContext()->getAsDecl())) {
-
-          // FIXME: these owningDecl names are kinda bad. like just `init(describing:)`
-          if (noncopyableTy->is<AnyMetatypeType>())
-            emitDiagnostic(diag::noncopyable_generics_generic_param_metatype,
-                           noncopyableTy->getMetatypeInstanceType(),
-                           paramDecl->getDescriptiveKind(),
-                           typeParam,
-                           owningDecl->getName(),
-                           noncopyableTy);
-          else
-            emitDiagnostic(diag::noncopyable_generics_generic_param,
-                           noncopyableTy,
-                           paramDecl->getDescriptiveKind(),
-                           typeParam,
-                           owningDecl->getName());
-
-          // If we have a location for the parameter, point it out in a note.
-          if (auto loc = paramDecl->getNameLoc()) {
-            emitDiagnosticAt(loc,
-                             diag::noncopyable_generics_implicit_copyable,
-                             paramDecl->getDescriptiveKind(),
-                             typeParam);
-          }
-
-          return true;
-        }
-      }
-      return false;
-    };
-
-    // NOTE: a non-requirement constraint locator might now be impossible.
-    if (diagnoseGenericTypeParamType(loc->getGenericParameter()))
-      return true;
-
-    if (auto tpr =
-        loc->getLastElementAs<LocatorPathElt::TypeParameterRequirement>()) {
-      auto signature = path[path.size() - 2]
-          .castTo<LocatorPathElt::OpenedGeneric>()
-          .getSignature();
-      auto requirement = signature.getRequirements()[tpr->getIndex()];
-      auto subject = requirement.getFirstType();
-
-      if (diagnoseGenericTypeParamType(subject->getAs<GenericTypeParamType>()))
-        return true;
-    }
-
-    if (loc->getLastElementAs<LocatorPathElt::ConditionalRequirement>())
-      return false; // Allow MissingConformanceFailure to diagnose instead.
-
-    break;
-  }
-  } // end switch
-
-  // emit catch-all diagnostic
-  emitDiagnostic(diag::noncopyable_generics, noncopyableTy);
-
-#ifndef NDEBUG
-#pragma clang diagnostic push
-#pragma clang diagnostic ignored "-Wdeprecated-declarations"
-    getLocator()->dump(&getConstraintSystem());
-#pragma clang diagnostic pop
-    llvm_unreachable("NoncopyableGenerics: vague diagnostic for locator");
-#endif
-
-  return true;
-}
-
 bool InvalidPackElement::diagnoseAsError() {
   emitDiagnostic(diag::each_non_pack, packElementType);
   return true;

lib/Sema/CSDiagnostics.h

@@ -1861,20 +1861,6 @@ class NotCompileTimeConstFailure final : public FailureDiagnostic {
   bool diagnoseAsError() override;
 };
 
-class NotCopyableFailure final : public FailureDiagnostic {
-  Type noncopyableTy;
-  NoncopyableMatchFailure failure;
-public:
-  NotCopyableFailure(const Solution &solution,
-                     Type noncopyableTy,
-                     NoncopyableMatchFailure failure,
-                     ConstraintLocator *locator)
-      : FailureDiagnostic(solution, locator),
-        noncopyableTy(noncopyableTy), failure(failure) {}
-
-  bool diagnoseAsError() override;
-};
-
 /// Diagnose \c each applied to an expression that is not a pack type.
 class InvalidPackElement final : public FailureDiagnostic {
   Type packElementType;

lib/Sema/CSFix.cpp

@@ -1361,45 +1361,6 @@ bool NotCompileTimeConst::diagnose(const Solution &solution, bool asNote) const
   return failure.diagnose(asNote);
 }
 
-MustBeCopyable::MustBeCopyable(ConstraintSystem &cs,
-                               Type noncopyableTy,
-                               NoncopyableMatchFailure failure,
-                               ConstraintLocator *locator)
-    : ConstraintFix(cs, FixKind::MustBeCopyable, locator, FixBehavior::Error),
-      noncopyableTy(noncopyableTy), failure(failure) {}
-
-bool MustBeCopyable::diagnose(const Solution &solution, bool asNote) const {
-  NotCopyableFailure failDiag(solution, noncopyableTy, failure, getLocator());
-  return failDiag.diagnose(asNote);
-}
-
-MustBeCopyable* MustBeCopyable::create(ConstraintSystem &cs,
-                                              Type noncopyableTy,
-                                              NoncopyableMatchFailure failure,
-                                              ConstraintLocator *locator) {
-  return new (cs.getAllocator()) MustBeCopyable(cs, noncopyableTy,
-                                                failure, locator);
-}
-
-bool MustBeCopyable::diagnoseForAmbiguity(CommonFixesArray commonFixes) const {
-  // Only diagnose if all solutions agreed on the same errant non-copyable type.
-  Type firstNonCopyable;
-  for (const auto &solutionAndFix : commonFixes) {
-    const auto *solution = solutionAndFix.first;
-    const auto *fix = solutionAndFix.second->getAs<MustBeCopyable>();
-
-    auto otherNonCopyable = solution->simplifyType(fix->noncopyableTy);
-    if (!firstNonCopyable)
-      firstNonCopyable = otherNonCopyable;
-
-    if (firstNonCopyable->getCanonicalType() != otherNonCopyable->getCanonicalType()) {
-      return false; // fixes differed, so decline to emit a tailored diagnostic.
-    }
-  }
-
-  return diagnose(*commonFixes.front().first);
-}
-
 bool AllowInvalidPackElement::diagnose(const Solution &solution,
                                        bool asNote) const {
   InvalidPackElement failure(solution, packElementType, getLocator());

lib/Sema/CSSimplify.cpp

@@ -8850,18 +8850,6 @@ ConstraintSystem::SolutionKind ConstraintSystem::simplifyConformsToConstraint(
           return SolutionKind::Solved;
       }
     }
-
-    // If this is a failure to conform to Copyable, tailor the error message.
-    if (kind == ConstraintKind::ConformsTo &&
-        protocol->isSpecificProtocol(KnownProtocolKind::Copyable)) {
-      auto *fix =
-          MustBeCopyable::create(*this,
-                                 type,
-                                 NoncopyableMatchFailure::forCopyableConstraint(),
-                                 getConstraintLocator(locator));
-      if (!recordFix(fix))
-        return SolutionKind::Solved;
-    }
   }
 
   // There's nothing more we can do; fail.
@@ -15158,7 +15146,6 @@ ConstraintSystem::SolutionKind ConstraintSystem::simplifyFixConstraint(
   case FixKind::AllowAutoClosurePointerConversion:
   case FixKind::NotCompileTimeConst:
   case FixKind::RenameConflictingPatternVariables:
-  case FixKind::MustBeCopyable:
   case FixKind::AllowInvalidPackElement:
   case FixKind::AllowInvalidPackReference:
   case FixKind::AllowInvalidPackExpansion: