ExistentialTypeSyntaxChecker: Look through any and some

Author: AnthonyLatsis

lib/Sema/TypeCheckType.cpp

@@ -5980,33 +5980,28 @@ class ExistentialTypeSyntaxChecker : public ASTWalker {
     if (T->isInvalid())
       return Action::SkipNode();
 
-    // Arbitrary protocol constraints are OK on opaque types.
-    if (isa<OpaqueReturnTypeRepr>(T))
-      return Action::SkipNode();
-
-    // Arbitrary protocol constraints are okay for 'any' types.
-    if (isa<ExistentialTypeRepr>(T))
-      return Action::SkipNode();
+    reprStack.push_back(T);
 
     // Suppressed conformance needs to be within any/some.
     if (auto inverse = dyn_cast<InverseTypeRepr>(T)) {
-      // Find an enclosing protocol composition, if there is one, so we
-      // can insert 'any' before that.
-      SourceLoc anyLoc = inverse->getTildeLoc();
-      if (!reprStack.empty()) {
-        if (isa<CompositionTypeRepr>(reprStack.back())) {
-          anyLoc = reprStack.back()->getStartLoc();
+      if (isAnyOrSomeMissing()) {
+        // Find an enclosing protocol composition, if there is one, so we
+        // can insert 'any' before that.
+        SourceLoc anyLoc = inverse->getTildeLoc();
+        if (reprStack.size() > 1) {
+          if (auto *repr =
+                  dyn_cast<CompositionTypeRepr>(*(reprStack.end() - 2))) {
+            anyLoc = repr->getStartLoc();
+          }
         }
-      }
 
-      Ctx.Diags.diagnose(inverse->getTildeLoc(), diag::inverse_requires_any)
-        .highlight(inverse->getConstraint()->getSourceRange())
-        .fixItInsert(anyLoc, "any ");
-      return Action::SkipNode();
+        Ctx.Diags.diagnose(inverse->getTildeLoc(), diag::inverse_requires_any)
+            .highlight(inverse->getConstraint()->getSourceRange())
+            .fixItInsert(anyLoc, "any ");
+      }
+      return Action::SkipChildren();
     }
 
-    reprStack.push_back(T);
-
     auto *declRefTR = dyn_cast<DeclRefTypeRepr>(T);
     if (!declRefTR) {
       return Action::Continue();
@@ -6135,6 +6130,40 @@ class ExistentialTypeSyntaxChecker : public ASTWalker {
     diag.fixItReplace(replaceRepr->getSourceRange(), fix);
   }
 
+  /// Returns a Boolean value indicating whether the type representation being
+  /// visited, assuming it is a constraint type demanding `any` or `some`, is
+  /// missing either keyword.
+  bool isAnyOrSomeMissing() const {
+    if (reprStack.size() < 2) {
+      return true;
+    }
+
+    auto it = reprStack.end() - 1;
+    while (true) {
+      --it;
+      if (it == reprStack.begin()) {
+        break;
+      }
+
+      // Look through parens, inverses, metatypes, and compositions.
+      if ((*it)->isParenType() || isa<InverseTypeRepr>(*it) ||
+          isa<CompositionTypeRepr>(*it) || isa<MetatypeTypeRepr>(*it)) {
+        continue;
+      }
+
+      // Look through '?' and '!' too; `any P?` et al. is diagnosed in the
+      // type resolver.
+      if (isa<OptionalTypeRepr>(*it) ||
+          isa<ImplicitlyUnwrappedOptionalTypeRepr>(*it)) {
+        continue;
+      }
+
+      break;
+    }
+
+    return !(isa<OpaqueReturnTypeRepr>(*it) || isa<ExistentialTypeRepr>(*it));
+  }
+
   void checkDeclRefTypeRepr(DeclRefTypeRepr *T) const {
     assert(!T->isInvalid());
 
@@ -6148,7 +6177,7 @@ class ExistentialTypeSyntaxChecker : public ASTWalker {
     }
 
     if (auto *proto = dyn_cast<ProtocolDecl>(decl)) {
-      if (proto->existentialRequiresAny()) {
+      if (proto->existentialRequiresAny() && isAnyOrSomeMissing()) {
         auto diag =
             Ctx.Diags.diagnose(T->getNameLoc(), diag::existential_requires_any,
                                proto->getDeclaredInterfaceType(),
@@ -6178,7 +6207,7 @@ class ExistentialTypeSyntaxChecker : public ASTWalker {
         if (auto *PCT = type->getAs<ProtocolCompositionType>())
           diagnose |= !PCT->getInverses().empty();
 
-        if (diagnose) {
+        if (diagnose && isAnyOrSomeMissing()) {
           auto diag = Ctx.Diags.diagnose(
               T->getNameLoc(), diag::existential_requires_any,
               alias->getDeclaredInterfaceType(),

test/decl/protocol/protocols.swift

@@ -103,9 +103,9 @@ struct DoesNotConform : Up {
 // Circular protocols
 
 protocol CircleMiddle : CircleStart { func circle_middle() }
-// expected-note@-1 2 {{protocol 'CircleMiddle' declared here}}
-protocol CircleStart : CircleEnd { func circle_start() } // expected-error 2 {{protocol 'CircleStart' refines itself}}
-protocol CircleEnd : CircleMiddle { func circle_end()} // expected-note 2 {{protocol 'CircleEnd' declared here}}
+// expected-note@-1 3 {{protocol 'CircleMiddle' declared here}}
+protocol CircleStart : CircleEnd { func circle_start() } // expected-error 3 {{protocol 'CircleStart' refines itself}}
+protocol CircleEnd : CircleMiddle { func circle_end()} // expected-note 3 {{protocol 'CircleEnd' declared here}}
 
 protocol CircleEntry : CircleTrivial { }
 protocol CircleTrivial : CircleTrivial { } // expected-error {{protocol 'CircleTrivial' refines itself}}

test/type/explicit_existential.swift

@@ -433,12 +433,16 @@ func testAnyFixIt() {
   // expected-error@+1 {{constraint that suppresses conformance requires 'any'}}{{21-21=any }}
   let _: (borrowing ~Copyable) -> Void
   // https://github.com/apple/swift/issues/72588
-  // FIXME: No diagnostic.
+  // expected-error@+1 {{use of protocol 'HasAssoc' as a type must be written 'any HasAssoc'}}{{30-38=any HasAssoc}}
   let _: any HasAssocGeneric<HasAssoc>
+  // expected-error@+1 {{constraint that suppresses conformance requires 'any'}}{{30-30=any }}
   let _: any HasAssocGeneric<~Copyable>
+  // expected-error@+1 {{use of protocol 'HasAssoc' as a type must be written 'any HasAssoc'}}{{16-24=any HasAssoc}}
   let _: any G<HasAssoc>.HasAssoc_Alias
+  // FIXME: Generic argument not diagnosed.
   let _: any ~G<HasAssoc>.Copyable_Alias
   do {
+    // expected-error@+1 {{use of protocol 'HasAssoc' as a type must be written 'any HasAssoc'}}{{22-30=any HasAssoc}}
     func f(_: some G<HasAssoc>.HasAssoc_Alias) {}
   }
 
@@ -448,6 +452,7 @@ func testAnyFixIt() {
   // expected-error@+2 {{constraint that suppresses conformance requires 'any'}}{{21-21=any }}
   // expected-error@+1 {{use of protocol 'NonCopyableHasAssoc' as a type must be written 'any NonCopyableHasAssoc'}}{{21-40=any NonCopyableHasAssoc}}
   let _: (borrowing NonCopyableHasAssoc & ~Copyable) -> Void
+  let _: any (((((~Copyable) & NonCopyableHasAssoc) & NonCopyableHasAssoc).Type.Type)).Type // OK
 
   // Misplaced '?'.
 

test/type/explicit_existential_swift6.swift

@@ -94,7 +94,7 @@ func testHasAssoc(_ x: Any, _: any HasAssoc) {
 
     func method() -> any HasAssoc {}
     func existentialArray() ->  [any HasAssoc] {}
-    func existentialcSequence() ->  any Sequence<HasAssoc> {}
+    func existentialcSequence() ->  any Sequence<any HasAssoc> {}
   }
 }
 
@@ -465,12 +465,16 @@ func testAnyFixIt() {
   // expected-error@+1 {{constraint that suppresses conformance requires 'any'}}{{21-21=any }}
   let _: (borrowing ~Copyable) -> Void
   // https://github.com/apple/swift/issues/72588
-  // FIXME: No diagnostic.
+  // expected-error@+1 {{use of protocol 'HasAssoc' as a type must be written 'any HasAssoc'}}{{30-38=any HasAssoc}}
   let _: any HasAssocGeneric<HasAssoc>
+  // expected-error@+1 {{constraint that suppresses conformance requires 'any'}}{{30-30=any }}
   let _: any HasAssocGeneric<~Copyable>
+  // expected-error@+1 {{use of protocol 'HasAssoc' as a type must be written 'any HasAssoc'}}{{16-24=any HasAssoc}}
   let _: any G<HasAssoc>.HasAssoc_Alias
+  // FIXME: Generic argument not diagnosed.
   let _: any ~G<HasAssoc>.Copyable_Alias
   do {
+    // expected-error@+1 {{use of protocol 'HasAssoc' as a type must be written 'any HasAssoc'}}{{22-30=any HasAssoc}}
     func f(_: some G<HasAssoc>.HasAssoc_Alias) {}
   }
 
@@ -480,6 +484,7 @@ func testAnyFixIt() {
   // expected-error@+2 {{constraint that suppresses conformance requires 'any'}}{{21-21=any }}
   // expected-error@+1 {{use of protocol 'NonCopyableHasAssoc' as a type must be written 'any NonCopyableHasAssoc'}}{{21-40=any NonCopyableHasAssoc}}
   let _: (borrowing NonCopyableHasAssoc & ~Copyable) -> Void
+  let _: any (((((~Copyable) & NonCopyableHasAssoc) & NonCopyableHasAssoc).Type.Type)).Type // OK
 
   // Misplaced '?'.