[Macros] Type-check attached macro arguments.

Author: hborla

lib/Sema/ConstraintSystem.cpp

@@ -3590,7 +3590,7 @@ void ConstraintSystem::resolveOverload(ConstraintLocator *locator,
     if (auto macro = dyn_cast<MacroDecl>(decl)) {
       // Macro can only be used in an expansion. If we end up here, it's
       // because we found a macro but are missing the leading '#'.
-      if (!locator->isForMacroExpansion()) {
+      if (!(locator->isForMacroExpansion() || locator->getAnchor().isImplicit())) {
         // Record a fix here
         (void)recordFix(MacroMissingPound::create(*this, macro, locator));
       }

lib/Sema/TypeCheckMacros.cpp

@@ -1092,7 +1092,7 @@ swift::findMacroForCustomAttr(CustomAttr *attr, DeclContext *dc) {
   // Look for macros at module scope. They can only occur at module scope, and
   // we need to be sure not to trigger name lookup into type contexts along
   // the way.
-  llvm::TinyPtrVector<MacroDecl *> macros;
+  llvm::TinyPtrVector<ValueDecl *> macros;
   auto moduleScopeDC = dc->getModuleScopeContext();
   ASTContext &ctx = moduleScopeDC->getASTContext();
   UnqualifiedLookupDescriptor descriptor(
@@ -1110,16 +1110,28 @@ swift::findMacroForCustomAttr(CustomAttr *attr, DeclContext *dc) {
   if (macros.empty())
     return nullptr;
 
-  if (macros.size() > 1) {
-    ctx.Diags.diagnose(attr->getLocation(), diag::ambiguous_macro_reference,
-                       identTypeRepr->getNameRef().getFullName());
-
-    for (auto macro : macros) {
-      macro->diagnose(
-          diag::kind_declname_declared_here, macro->getDescriptiveKind(),
-          macro->getName());
-    }
+  // Extract macro arguments from the attribute, or create an empty list.
+  ArgumentList *attrArgs;
+  if (attr->hasArgs()) {
+    attrArgs = attr->getArgs();
+  } else {
+    attrArgs = ArgumentList::createImplicit(ctx, {});
   }
 
-  return macros.front();
+  // Form an `OverloadedDeclRefExpr` with the filtered lookup result above
+  // to ensure @freestanding macros are not considered in overload resolution.
+  FunctionRefKind functionRefKind = FunctionRefKind::SingleApply;
+  auto macroRefExpr = new (ctx) OverloadedDeclRefExpr(
+      macros, identTypeRepr->getNameLoc(), functionRefKind,
+      /*implicit*/true);
+  auto *call = CallExpr::createImplicit(ctx, macroRefExpr, attrArgs);
+
+  Expr *result = call;
+  TypeChecker::typeCheckExpression(result, dc);
+
+  if (auto *fn = dyn_cast<DeclRefExpr>(call->getFn()))
+    if (auto *macro = dyn_cast<MacroDecl>(fn->getDecl()))
+      return macro;
+
+  return dyn_cast<MacroDecl>(macros.front());
 }

test/Macros/accessor_macros.swift

@@ -17,7 +17,7 @@
 // REQUIRES: OS=macosx
 
 @attached(accessor)
-macro myPropertyWrapper: Void =
+macro myPropertyWrapper() =
     #externalMacro(module: "MacroDefinition", type: "PropertyWrapperMacro")
 
 struct Date { }

test/Macros/attached_macros_diags.swift

@@ -1,21 +1,21 @@
 // RUN: %target-typecheck-verify-swift -enable-experimental-feature Macros -module-name MacrosTest
 
-@attached(accessor) macro m1: Void = #externalMacro(module: "MyMacros", type: "Macro1")
-// expected-warning@-1{{external macro implementation type 'MyMacros.Macro1' could not be found for macro 'm1'}}
-// expected-note@-2{{'m1' declared here}}
+@attached(accessor) macro m1() = #externalMacro(module: "MyMacros", type: "Macro1")
+// expected-warning@-1{{external macro implementation type 'MyMacros.Macro1' could not be found for macro 'm1()'}}
+// expected-note@-2{{'m1()' declared here}}
 
 @attached(accessor) macro m2(_: Int) -> Void = #externalMacro(module: "MyMacros", type: "Macro2")
 // expected-warning@-1{{external macro implementation type 'MyMacros.Macro2' could not be found for macro 'm2'}}
-// expected-note@-2 2{{macro 'm2' declared here}}
+// expected-note@-2 2{{candidate has partially matching parameter list (Int)}}
 
 @attached(accessor) macro m2(_: Double) -> Void = #externalMacro(module: "MyMacros", type: "Macro2")
 // expected-warning@-1{{external macro implementation type 'MyMacros.Macro2' could not be found for macro 'm2'}}
-// expected-note@-2 2{{macro 'm2' declared here}}
+// expected-note@-2 2{{candidate has partially matching parameter list (Double)}}
 
 @m1 struct X1 { }
 
 // FIXME: Redundant diagnostic
-@m2 struct X2 { } // expected-error 2{{ambiguous reference to macro 'm2'}}
+@m2 struct X2 { } // expected-error 2{{no exact matches in call to macro 'm2'}}
 
 // Check for nesting rules.
 struct SkipNestedType {
@@ -28,5 +28,5 @@ struct SkipNestedType {
 
   // We select the macro, not the property wrapper.
   @m1 var x: Int = 0
-  // expected-error@-1{{external macro implementation type 'MyMacros.Macro1' could not be found for macro 'm1'; the type must be public and provided via '-load-plugin-library'}}
+  // expected-error@-1{{external macro implementation type 'MyMacros.Macro1' could not be found for macro 'm1()'; the type must be public and provided via '-load-plugin-library'}}
 }

test/Serialization/Inputs/def_macros.swift

@@ -2,7 +2,7 @@
 
 @expression macro internalStringify<T>(_ value: T) -> (T, String) = #externalMacro(module: "MacroDefinition", type: "StringifyMacro")
 
-@attached(accessor) public macro myWrapper: Void = #externalMacro(module: "MacroDefinition", type: "MyWrapperMacro")
+@attached(accessor) public macro myWrapper() = #externalMacro(module: "MacroDefinition", type: "MyWrapperMacro")
 
 @attached(memberAttributes) public macro wrapAllProperties() = #externalMacro(module: "MacroDefinition", type: "WrapAllProperties")