[Macros] Check access control and availability

Author: DougGregor

include/swift/AST/DiagnosticsSema.def

@@ -6752,6 +6752,21 @@ WARNING(macro_warning, none,
         "%1 (in macro %0)", (DeclName, StringRef))
 ERROR(macro_error, none,
       "%1 (in macro %0)", (DeclName, StringRef))
+ERROR(macro_type_access,none,
+      "macro %select{must be declared "
+      "%select{private|fileprivate|internal|%error|%error}1"
+      "|cannot be declared "
+      "%select{in this context|fileprivate|internal|public|open}1}0 "
+      "because its %select{parameter|result type}3 uses "
+      "%select{a private|a fileprivate|an internal|%error|%error}2 type",
+      (bool, AccessLevel, AccessLevel, bool))
+WARNING(macro_type_access_warn,none,
+        "macro %select{should be declared "
+        "%select{private|fileprivate|internal|%error|%error}1"
+        "|should not be declared %select{in this context|fileprivate|internal|public|open}1}0 "
+        "because its %select{parameter|result type}3 uses "
+        "%select{a private|a fileprivate|an internal|%error|%error}2 type",
+        (bool, AccessLevel, AccessLevel, bool))
 
 //------------------------------------------------------------------------------
 // MARK: Move Only Errors

lib/Sema/TypeCheckAccess.cpp

@@ -471,7 +471,6 @@ class AccessControlChecker : public AccessControlCheckerBase,
   UNREACHABLE(Operator, "cannot appear in a type context")
   UNREACHABLE(PrecedenceGroup, "cannot appear in a type context")
   UNREACHABLE(Module, "cannot appear in a type context")
-  UNREACHABLE(Macro, "cannot appear in a type context")
 
   UNREACHABLE(IfConfig, "does not have access control")
   UNREACHABLE(PoundDiagnostic, "does not have access control")
@@ -1056,6 +1055,62 @@ class AccessControlChecker : public AccessControlCheckerBase,
           });
     }
   }
+
+  void visitMacroDecl(MacroDecl *MD) {
+    checkGenericParamAccess(MD, MD);
+
+    auto minAccessScope = AccessScope::getPublic();
+    const TypeRepr *complainRepr = nullptr;
+    auto downgradeToWarning = DowngradeToWarning::No;
+    bool problemIsResult = false;
+
+    if (MD->parameterList) {
+      for (auto *P : *MD->parameterList) {
+        checkTypeAccess(
+            P->getInterfaceType(), P->getTypeRepr(), MD, /*mayBeInferred*/ false,
+            [&](AccessScope typeAccessScope, const TypeRepr *thisComplainRepr,
+                DowngradeToWarning downgradeDiag) {
+              if (typeAccessScope.isChildOf(minAccessScope) ||
+                  (!complainRepr &&
+                   typeAccessScope.hasEqualDeclContextWith(minAccessScope))) {
+                minAccessScope = typeAccessScope;
+                complainRepr = thisComplainRepr;
+                downgradeToWarning = downgradeDiag;
+              }
+            });
+      }
+    }
+
+    checkTypeAccess(MD->getResultInterfaceType(), MD->resultType.getTypeRepr(),
+                    MD, /*mayBeInferred*/false,
+                    [&](AccessScope typeAccessScope,
+                        const TypeRepr *thisComplainRepr,
+                        DowngradeToWarning downgradeDiag) {
+      if (typeAccessScope.isChildOf(minAccessScope) ||
+          (!complainRepr &&
+           typeAccessScope.hasEqualDeclContextWith(minAccessScope))) {
+        minAccessScope = typeAccessScope;
+        complainRepr = thisComplainRepr;
+        downgradeToWarning = downgradeDiag;
+        problemIsResult = true;
+      }
+    });
+
+    if (!minAccessScope.isPublic()) {
+      auto minAccess = minAccessScope.accessLevelForDiagnostics();
+      bool isExplicit =
+        MD->getAttrs().hasAttribute<AccessControlAttr>();
+      auto diagID = diag::macro_type_access;
+      if (downgradeToWarning == DowngradeToWarning::Yes)
+        diagID = diag::macro_type_access_warn;
+      auto macroDeclAccess = isExplicit
+        ? MD->getFormalAccess()
+        : minAccessScope.requiredAccessForDiagnostics();
+      auto diag = MD->diagnose(diagID, isExplicit, macroDeclAccess,
+                               minAccess, problemIsResult);
+      highlightOffendingType(diag, complainRepr);
+    }
+  }
 };
 
 class UsableFromInlineChecker : public AccessControlCheckerBase,
@@ -1099,7 +1154,6 @@ class UsableFromInlineChecker : public AccessControlCheckerBase,
   UNREACHABLE(Operator, "cannot appear in a type context")
   UNREACHABLE(PrecedenceGroup, "cannot appear in a type context")
   UNREACHABLE(Module, "cannot appear in a type context")
-  UNREACHABLE(Macro, "cannot appear in a type context")
 
   UNREACHABLE(Param, "does not have access control")
   UNREACHABLE(GenericTypeParam, "does not have access control")
@@ -1118,6 +1172,7 @@ class UsableFromInlineChecker : public AccessControlCheckerBase,
   UNINTERESTING(Destructor) // Always correct.
   UNINTERESTING(Accessor) // Handled by the Var or Subscript.
   UNINTERESTING(OpaqueType) // Handled by the Var or Subscript.
+  UNINTERESTING(Macro)
 
   /// If \p VD's layout is exposed by a @frozen struct or class, return said
   /// struct or class.
@@ -1709,7 +1764,6 @@ class DeclAvailabilityChecker : public DeclVisitor<DeclAvailabilityChecker> {
   UNREACHABLE(Import, "not applicable")
   UNREACHABLE(TopLevelCode, "not applicable")
   UNREACHABLE(Module, "not applicable")
-  UNREACHABLE(Macro, "not applicable")
 
   UNREACHABLE(Param, "handled by the enclosing declaration")
   UNREACHABLE(GenericTypeParam, "handled by the enclosing declaration")
@@ -1906,6 +1960,17 @@ class DeclAvailabilityChecker : public DeclVisitor<DeclAvailabilityChecker> {
       checkType(P->getInterfaceType(), P->getTypeRepr(), EED);
   }
 
+  void visitMacroDecl(MacroDecl *MD) {
+    checkGenericParams(MD, MD);
+
+    if (MD->parameterList) {
+      for (auto P : *MD->parameterList) {
+        checkType(P->getInterfaceType(), P->getTypeRepr(), MD);
+      }
+    }
+    checkType(MD->getResultInterfaceType(), MD->resultType.getTypeRepr(), MD);
+  }
+
   void checkConstrainedExtensionRequirements(ExtensionDecl *ED,
                                              bool hasExportedMembers) {
     if (!ED->getTrailingWhereClause())

lib/Sema/TypeCheckDeclPrimary.cpp

@@ -1983,7 +1983,9 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
   }
 
   void visitMacroDecl(MacroDecl *MD) {
-    // Macros have no definitions, so there is nothing to check.
+    TypeChecker::checkDeclAttributes(MD);
+    // FIXME: Check for redeclarations
+    checkAccessControl(MD);
   }
 
   void visitMacroExpansionDecl(MacroExpansionDecl *MED) {

test/Macros/macro_availability_macosx.swift

@@ -0,0 +1,10 @@
+// RUN: %target-typecheck-verify-swift -enable-experimental-feature Macros -module-name MacrosTest -target %target-cpu-apple-macosx11
+// REQUIRES: OS=macosx
+
+@available(macOS 12.0, *)
+struct X { }
+
+macro m1: X = A.B // expected-error{{'X' is only available in macOS 12.0 or newer}}
+
+@available(macOS 12.0, *)
+macro m2: X = A.B

test/Macros/macros_diagnostics.swift

@@ -8,6 +8,10 @@ protocol P { }
 macro tryToHide<T: P>(_: P) -> some P = BuiltinMacros.Blah
 // expected-error@-1{{some' types are only permitted in properties, subscripts, and functions}}
 
+internal struct X { } // expected-note{{type declared here}}
+
+public macro createAnX: X = BuiltinMacros.Blah
+// expected-error@-1{{macro cannot be declared public because its result type uses an internal type}}
 
 func test(a: Int, b: Int) {
   // FIXME: Bad diagnostic.

test/Macros/parsing.swift

@@ -1,10 +1,11 @@
 // RUN: %target-typecheck-verify-swift -enable-experimental-feature Macros
 protocol P { }
+protocol Q { associatedtype Assoc }
 
 macro m1: Int = A.M1
 macro m2(_: Int) = A.M2
 macro m3(a b: Int) -> Int = A.M3
-macro m4<T>: T = A.M4 where T.Assoc: P
+macro m4<T: Q>: T = A.M4 where T.Assoc: P
 macro m5<T: P>(_: T) = A.M4
 
 macro m6 = A // expected-error{{expected '(' for macro parameters or ':' for a value-like macro}}