[cxx-interop] Fix transforming spans that are not behind type aliases

While we expect our users to use type aliases for template
instantiations, there are some contexts when we import instantiations
without aliases. Unfortunately, in case of C++ span we generated a name
for the instantiation that cannot be a syntactically valid Swift type
due to unary negation appearing in the type name. This PR replaces the
unary negation with "Neg" in the type name and also fixed a bug that
ended up printing certain unsigned values as signed. Moreover, this PR
also fixes some other fallouts in the SwiftifyImport macro.

rdar://146833480

Author: Gabor Horvath

lib/ClangImporter/ClangClassTemplateNamePrinter.cpp

@@ -203,7 +203,12 @@ struct TemplateArgumentPrinter
     if (arg.getIntegralType()->isBuiltinType()) {
       buffer << typePrinter.Visit(arg.getIntegralType().getTypePtr()) << "_";
     }
-    arg.getAsIntegral().print(buffer, true);
+    auto value = arg.getAsIntegral();
+    if (value.isNegative()) {
+      value.negate();
+      buffer << "Neg_";
+    }
+    value.print(buffer, arg.getIntegralType()->isSignedIntegerType());
   }
 
   void VisitPackTemplateArgument(const clang::TemplateArgument &arg,

lib/Macros/Sources/SwiftMacros/SwiftifyImportMacro.swift

@@ -168,6 +168,13 @@ enum Mutability {
   case Mutable
 }
 
+func getUnattributedType(_ type: TypeSyntax) -> TypeSyntax {
+  if let attributedType = type.as(AttributedTypeSyntax.self) {
+    return attributedType.baseType.trimmed
+  }
+  return type.trimmed
+}
+
 func getTypeName(_ type: TypeSyntax) throws -> TokenSyntax {
   switch type.kind {
   case .memberType:
@@ -410,7 +417,7 @@ struct CxxSpanThunkBuilder: ParamPointerBoundsThunkBuilder {
   func buildFunctionSignature(_ argTypes: [Int: TypeSyntax?], _ returnType: TypeSyntax?) throws
     -> (FunctionSignatureSyntax, Bool) {
     var types = argTypes
-    let typeName = try getTypeName(oldType).text
+    let typeName = getUnattributedType(oldType).description
     guard let desugaredType = typeMappings[typeName] else {
       throw DiagnosticError(
         "unable to desugar type with name '\(typeName)'", node: node)
@@ -426,7 +433,7 @@ struct CxxSpanThunkBuilder: ParamPointerBoundsThunkBuilder {
 
   func buildFunctionCall(_ pointerArgs: [Int: ExprSyntax]) throws -> ExprSyntax {
     var args = pointerArgs
-    let typeName = try getTypeName(oldType).text
+    let typeName = getUnattributedType(oldType).description
     assert(args[index] == nil)
     args[index] = ExprSyntax("\(raw: typeName)(\(raw: name))")
     return try base.buildFunctionCall(args)
@@ -446,7 +453,7 @@ struct CxxSpanReturnThunkBuilder: BoundsCheckedThunkBuilder {
   func buildFunctionSignature(_ argTypes: [Int: TypeSyntax?], _ returnType: TypeSyntax?) throws
     -> (FunctionSignatureSyntax, Bool) {
     assert(returnType == nil)
-    let typeName = try getTypeName(signature.returnClause!.type).text
+    let typeName = getUnattributedType(signature.returnClause!.type).description
     guard let desugaredType = typeMappings[typeName] else {
       throw DiagnosticError(
         "unable to desugar type with name '\(typeName)'", node: node)
@@ -923,19 +930,15 @@ public struct SwiftifyImportMacro: PeerMacro {
       return []
     }
     var result : [ParamInfo] = []
-    let process = { type, expr, orig in
-      do {
-        let typeName = try getTypeName(type).text
-        if let desugaredType = typeMappings[typeName] {
-          if let unqualifiedDesugaredType = getUnqualifiedStdName(desugaredType) {
-            if unqualifiedDesugaredType.starts(with: "span<") {
-              result.append(CxxSpan(pointerIndex: expr, nonescaping: false,
-                dependencies: [], typeMappings: typeMappings, original: orig))
-            }
+    let process : (TypeSyntax, SwiftifyExpr, SyntaxProtocol) throws -> () = { type, expr, orig in
+      let typeName = getUnattributedType(type).description
+      if let desugaredType = typeMappings[typeName] {
+        if let unqualifiedDesugaredType = getUnqualifiedStdName(desugaredType) {
+          if unqualifiedDesugaredType.starts(with: "span<") {
+            result.append(CxxSpan(pointerIndex: expr, nonescaping: false,
+              dependencies: [], typeMappings: typeMappings, original: orig))
           }
         }
-      } catch is DiagnosticError {
-        // type doesn't match expected pattern
       }
     }
     for (idx, param) in signature.parameterClause.parameters.enumerated() {

test/Interop/Cxx/stdlib/Inputs/std-span.h

@@ -121,4 +121,9 @@ inline ConstSpanOfInt mixedFuncWithSafeWrapper7(const int * __counted_by(len) p,
   return ConstSpanOfInt(p, len);
 }
 
+struct SpanWithoutTypeAlias {
+  std::span<const int> bar() [[clang::lifetimebound]];
+  void foo(std::span<const int> s [[clang::noescape]]);
+};
+
 #endif // TEST_INTEROP_CXX_STDLIB_INPUTS_STD_SPAN_H

test/Interop/Cxx/stdlib/std-span-interface.swift

@@ -27,6 +27,14 @@ import CxxStdlib
 // CHECK-NEXT:   @_alwaysEmitIntoClient public mutating func methodWithSafeWrapper(_ s: Span<CInt>)
 // CHECK-NEXT:   mutating func methodWithSafeWrapper(_ s: ConstSpanOfInt)
 // CHECK-NEXT: }
+// CHECK: struct SpanWithoutTypeAlias {
+// CHECK-NEXT:   init()
+// CHECK-NEXT:   @lifetime(borrow self)
+// CHECK-NEXT:   @_alwaysEmitIntoClient @_disfavoredOverload public mutating func bar() -> Span<CInt>
+// CHECK-NEXT:   mutating func bar() -> std.{{.*}}span<__cxxConst<CInt>, _C{{.*}}_{{.*}}>
+// CHECK-NEXT:   @_alwaysEmitIntoClient public mutating func foo(_ s: Span<CInt>)
+// CHECK-NEXT:   mutating func foo(_ s: std.{{.*}}span<__cxxConst<CInt>, _C{{.*}}_{{.*}}>)
+// CHECK-NEXT: }
 // CHECK: @_alwaysEmitIntoClient public func funcWithSafeWrapper(_ s: Span<CInt>)
 // CHECK-NEXT: @lifetime(s)
 // CHECK-NEXT: @_alwaysEmitIntoClient public func funcWithSafeWrapper2(_ s: Span<CInt>) -> Span<CInt>

test/Interop/Cxx/templates/Inputs/class-template-non-type-parameter.h

@@ -10,4 +10,11 @@ template <class T, size_t Size> struct MagicArray { T t[Size]; };
 typedef MagicArray<int, 2> MagicIntPair;
 typedef MagicArray<int, 3> MagicIntTriple;
 
+template <typename T, T Val>
+struct integral_constant {
+  constexpr static T value = Val;
+};
+
+typedef integral_constant<int, -3> NegativeThree;
+
 #endif // TEST_INTEROP_CXX_TEMPLATES_INPUTS_CLASS_TEMPLATE_NON_TYPE_PARAMETER_H

test/Interop/Cxx/templates/class-template-non-type-parameter-module-interface.swift

@@ -17,3 +17,4 @@
 
 // CHECK: typealias MagicIntPair = MagicArray<CInt, _C{{.*}}_2>
 // CHECK: typealias MagicIntTriple = MagicArray<CInt, _C{{.*}}_3>
+// CHECK: typealias NegativeThree = integral_constant<CInt, _C{{.*}}_Neg_3>