Merge pull request swiftlang#59835 from DougGregor/preconcurrency-sendable-function-conversion-5.7

Introduce function conversions for @preconcurrency-adjusted declaration references

Author: DougGregor

include/swift/AST/Expr.h

@@ -4553,7 +4553,7 @@ class ApplyExpr : public Expr {
     Bits.ApplyExpr.ShouldApplyDistributedThunk = flag;
   }
 
-  ValueDecl *getCalledValue() const;
+  ValueDecl *getCalledValue(bool skipFunctionConversions = false) const;
 
   static bool classof(const Expr *E) {
     return E->getKind() >= ExprKind::First_ApplyExpr &&

include/swift/Sema/ConstraintSystem.h

@@ -614,11 +614,19 @@ struct SelectedOverload {
   /// we're referencing a member.
   const Type openedFullType;
 
+  /// The opened type of the base of the reference to this overload, adjusted
+  /// for `@preconcurrency` or other contextual type-altering attributes.
+  const Type adjustedOpenedFullType;
+
   /// The opened type produced by referring to this overload.
   const Type openedType;
 
+  /// The opened type produced by referring to this overload, adjusted for
+  /// `@preconcurrency` or other contextual type-altering attributes.
+  const Type adjustedOpenedType;
+
   /// The type that this overload binds. Note that this may differ from
-  /// openedType, for example it will include any IUO unwrapping that has taken
+  /// adjustedOpenedType, for example it will include any IUO unwrapping that has taken
   /// place.
   const Type boundType;
 };
@@ -2471,6 +2479,31 @@ struct GetClosureType {
   Type operator()(const AbstractClosureExpr *expr) const;
 };
 
+/// Describes the type produced when referencing a declaration.
+struct DeclReferenceType {
+  /// The "opened" type, which is the type of the declaration where any
+  /// generic parameters have been replaced with type variables.
+  ///
+  /// The mapping from generic parameters to type variables will have been
+  /// recorded by \c recordOpenedTypes when this type is produced.
+  Type openedType;
+
+  /// The opened type, after performing contextual type adjustments such as
+  /// removing concurrency-related annotations for a `@preconcurrency`
+  /// operation.
+  Type adjustedOpenedType;
+
+  /// The type of the reference, based on the original opened type. This is the
+  /// type that the expression used to form the declaration reference would
+  /// have if no adjustments had been applied.
+  Type referenceType;
+
+  /// The type of the reference, which is the adjusted opened type after
+  /// (e.g.) applying the base of a member access. This is the type of the
+  /// expression used to form the declaration reference.
+  Type adjustedReferenceType;
+};
+
 /// Describes a system of constraints on type variables, the
 /// solution of which assigns concrete types to each of the type variables.
 /// Constraint systems are typically generated given an (untyped) expression.
@@ -4423,10 +4456,11 @@ class ConstraintSystem {
          const OpenedTypeMap &replacements);
 
   /// Wrapper over swift::adjustFunctionTypeForConcurrency that passes along
-  /// the appropriate closure-type extraction function.
+  /// the appropriate closure-type and opening extraction functions.
   AnyFunctionType *adjustFunctionTypeForConcurrency(
     AnyFunctionType *fnType, ValueDecl *decl, DeclContext *dc,
-    unsigned numApplies, bool isMainDispatchQueue);
+    unsigned numApplies, bool isMainDispatchQueue,
+    OpenedTypeMap &replacements);
 
   /// Retrieve the type of a reference to the given value declaration.
   ///
@@ -4436,9 +4470,8 @@ class ConstraintSystem {
   ///
   /// \param decl The declarations whose type is being computed.
   ///
-  /// \returns a pair containing the full opened type (if applicable) and
-  /// opened type of a reference to declaration.
-  std::pair<Type, Type> getTypeOfReference(
+  /// \returns a description of the type of this declaration reference.
+  DeclReferenceType getTypeOfReference(
                           ValueDecl *decl,
                           FunctionRefKind functionRefKind,
                           ConstraintLocatorBuilder locator,
@@ -4486,6 +4519,14 @@ class ConstraintSystem {
           return Type();
         });
 
+  /// Given the opened type and a pile of information about a member reference,
+  /// determine the reference type of the member reference.
+  Type getMemberReferenceTypeFromOpenedType(
+      Type &openedType, Type baseObjTy, ValueDecl *value, DeclContext *outerDC,
+      ConstraintLocator *locator, bool hasAppliedSelf,
+      bool isStaticMemberRefOnProtocol, bool isDynamicResult,
+      OpenedTypeMap &replacements);
+
   /// Retrieve the type of a reference to the given value declaration,
   /// as a member with a base of the given type.
   ///
@@ -4496,9 +4537,8 @@ class ConstraintSystem {
   /// \param isDynamicResult Indicates that this declaration was found via
   /// dynamic lookup.
   ///
-  /// \returns a pair containing the full opened type (which includes the opened
-  /// base) and opened type of a reference to this member.
-  std::pair<Type, Type> getTypeOfMemberReference(
+  /// \returns a description of the type of this declaration reference.
+  DeclReferenceType getTypeOfMemberReference(
                           Type baseTy, ValueDecl *decl, DeclContext *useDC,
                           bool isDynamicResult,
                           FunctionRefKind functionRefKind,

lib/AST/Expr.cpp

@@ -1413,7 +1413,7 @@ DictionaryExpr *DictionaryExpr::create(ASTContext &C, SourceLoc LBracketLoc,
                                   Ty);
 }
 
-static ValueDecl *getCalledValue(Expr *E) {
+static ValueDecl *getCalledValue(Expr *E, bool skipFunctionConversions) {
   if (auto *DRE = dyn_cast<DeclRefExpr>(E))
     return DRE->getDecl();
 
@@ -1422,11 +1422,16 @@ static ValueDecl *getCalledValue(Expr *E) {
 
   // Look through SelfApplyExpr.
   if (auto *SAE = dyn_cast<SelfApplyExpr>(E))
-    return SAE->getCalledValue();
+    return SAE->getCalledValue(skipFunctionConversions);
+
+  if (skipFunctionConversions) {
+    if (auto fnConv = dyn_cast<FunctionConversionExpr>(E))
+      return getCalledValue(fnConv->getSubExpr(), skipFunctionConversions);
+  }
 
   Expr *E2 = E->getValueProvidingExpr();
   if (E != E2)
-    return getCalledValue(E2);
+    return getCalledValue(E2, skipFunctionConversions);
 
   return nullptr;
 }
@@ -1468,8 +1473,8 @@ Expr *DefaultArgumentExpr::getCallerSideDefaultExpr() const {
                            new (ctx) ErrorExpr(getSourceRange(), getType()));
 }
 
-ValueDecl *ApplyExpr::getCalledValue() const {
-  return ::getCalledValue(Fn);
+ValueDecl *ApplyExpr::getCalledValue(bool skipFunctionConversions) const {
+  return ::getCalledValue(Fn, skipFunctionConversions);
 }
 
 SubscriptExpr::SubscriptExpr(Expr *base, ArgumentList *argList,
@@ -1906,6 +1911,14 @@ Expr *AutoClosureExpr::getUnwrappedCurryThunkExpr() const {
     return expr;
   };
 
+  auto maybeUnwrapConversions = [](Expr *expr) {
+    if (auto *covariantReturn = dyn_cast<CovariantReturnConversionExpr>(expr))
+      expr = covariantReturn->getSubExpr();
+    if (auto *functionConversion = dyn_cast<FunctionConversionExpr>(expr))
+      expr = functionConversion->getSubExpr();
+    return expr;
+  };
+
   switch (getThunkKind()) {
   case AutoClosureExpr::Kind::None:
   case AutoClosureExpr::Kind::AsyncLet:
@@ -1916,6 +1929,7 @@ Expr *AutoClosureExpr::getUnwrappedCurryThunkExpr() const {
     body = body->getSemanticsProvidingExpr();
     body = maybeUnwrapOpenExistential(body);
     body = maybeUnwrapOptionalEval(body);
+    body = maybeUnwrapConversions(body);
 
     if (auto *outerCall = dyn_cast<ApplyExpr>(body)) {
       return outerCall->getFn();
@@ -1934,9 +1948,10 @@ Expr *AutoClosureExpr::getUnwrappedCurryThunkExpr() const {
       innerBody = innerBody->getSemanticsProvidingExpr();
       innerBody = maybeUnwrapOpenExistential(innerBody);
       innerBody = maybeUnwrapOptionalEval(innerBody);
-
+      innerBody = maybeUnwrapConversions(innerBody);
       if (auto *outerCall = dyn_cast<ApplyExpr>(innerBody)) {
-        if (auto *innerCall = dyn_cast<ApplyExpr>(outerCall->getFn())) {
+        auto outerFn = maybeUnwrapConversions(outerCall->getFn());
+        if (auto *innerCall = dyn_cast<ApplyExpr>(outerFn)) {
           return innerCall->getFn();
         }
       }

lib/SILGen/SILGenPoly.cpp

@@ -183,7 +183,7 @@ collectExistentialConformances(ModuleDecl *M, CanType fromType, CanType toType)
   SmallVector<ProtocolConformanceRef, 4> conformances;
   for (auto proto : protocols) {
     auto conformance =
-      M->lookupConformance(fromType, proto);
+      M->lookupConformance(fromType, proto, /*allowMissing=*/true);
     assert(conformance);
     conformances.push_back(conformance);
   }