[cfe] Dot shorthands: Static invocations are inferred.

Similar to constructor invocations, we infer the type parameters for the dot shorthand static member that we find.

Added language + cfe tests for this case.

This CL is a follow up to: https://dart-review.googlesource.com/c/sdk/+/417960/comment/90f32aed_8d1f6c01/

Bug: #59758
Change-Id: I96666ba9faa6ffaf42bd46e4d39175b88f7a353d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/420283
Reviewed-by: Chloe Stefantsova <[email protected]>
Commit-Queue: Kallen Tu <[email protected]>

Author: kallentu

pkg/front_end/lib/src/type_inference/inference_visitor.dart

@@ -12134,8 +12134,22 @@ class InferenceVisitorImpl extends InferenceVisitorBase
 
     Expression? expr;
     if (member is Procedure && member.kind == ProcedureKind.Method) {
+      // The shorthand expression is inferred in the empty context and then type
+      // inference infers the type arguments.
+      FunctionType functionType =
+          member.function.computeThisFunctionType(Nullability.nonNullable);
+      InvocationInferenceResult result = inferInvocation(
+          this,
+          typeContext,
+          node.fileOffset,
+          new InvocationTargetFunctionType(functionType),
+          node.arguments as ArgumentsImpl,
+          isConst: node.isConst,
+          staticTarget: member);
       expr = new StaticInvocation(member, node.arguments)
         ..fileOffset = node.fileOffset;
+      return new ExpressionInferenceResult(
+          result.inferredType, result.applyResult(expr));
     } else if (member == null && cachedContext is TypeDeclarationType) {
       // Couldn't find a static method in the declaration so we'll try and find
       // a constructor of that name instead.
@@ -12161,8 +12175,8 @@ class InferenceVisitorImpl extends InferenceVisitorBase
                   node.name.text.length));
         }
 
-        // With constructor invocations, the shorthand expression is preceded by
-        // the raw type and then type inference infers the type arguments.
+        // The shorthand expression is inferred in the empty context and then
+        // type inference infers the type arguments.
         FunctionType functionType = constructor.function
             .computeThisFunctionType(Nullability.nonNullable);
         InvocationInferenceResult result = inferInvocation(
@@ -12189,8 +12203,8 @@ class InferenceVisitorImpl extends InferenceVisitorBase
                   node.name.text.length));
         }
 
-        // With constructor invocations, the shorthand expression is preceded by
-        // the raw type and then type inference infers the type arguments.
+        // The shorthand expression is inferred in the empty context and then
+        // type inference infers the type arguments.
         FunctionType functionType = constructor.function
             .computeThisFunctionType(Nullability.nonNullable);
         InvocationInferenceResult result = inferInvocation(
@@ -12224,33 +12238,28 @@ class InferenceVisitorImpl extends InferenceVisitorBase
           isExpressionInvocation: true, isImplicitCall: true);
     }
 
-    if (expr == null) {
-      Expression replacement;
-      if (isKnown(cachedContext)) {
-        // Error when we can't find the static member or constructor named
-        // [node.name] in the declaration of [cachedContext].
-        replacement = helper.buildProblem(
-            templateDotShorthandsUndefinedInvocation.withArguments(
-                node.name.text, cachedContext),
-            node.nameOffset,
-            node.name.text.length);
-      } else {
-        // Error when no context type or an invalid context type is given to
-        // resolve the dot shorthand.
-        //
-        // e.g. `var x = .one;`
-        replacement = helper.buildProblem(
-            templateDotShorthandsInvalidContext.withArguments(node.name.text),
-            node.nameOffset,
-            node.name.text.length);
-      }
-      return new ExpressionInferenceResult(const DynamicType(), replacement);
+    // Error handling. At this point, we've exhausted all possible valid
+    // invocations.
+    Expression replacement;
+    if (isKnown(cachedContext)) {
+      // Error when we can't find the static member or constructor named
+      // [node.name] in the declaration of [cachedContext].
+      replacement = helper.buildProblem(
+          templateDotShorthandsUndefinedInvocation.withArguments(
+              node.name.text, cachedContext),
+          node.nameOffset,
+          node.name.text.length);
+    } else {
+      // Error when no context type or an invalid context type is given to
+      // resolve the dot shorthand.
+      //
+      // e.g. `var x = .one;`
+      replacement = helper.buildProblem(
+          templateDotShorthandsInvalidContext.withArguments(node.name.text),
+          node.nameOffset,
+          node.name.text.length);
     }
-
-    ExpressionInferenceResult expressionInferenceResult =
-        inferExpression(expr, cachedContext);
-    flowAnalysis.forwardExpression(expressionInferenceResult.expression, node);
-    return expressionInferenceResult;
+    return new ExpressionInferenceResult(const DynamicType(), replacement);
   }
 
   ExpressionInferenceResult visitDotShorthandPropertyGet(

pkg/front_end/testcases/dot_shorthands/static_method.dart

@@ -8,6 +8,13 @@ class Color {
   Color(this.x);
 }
 
+class C<T> {
+  static C<X> foo<X>(X x) => new C<X>();
+
+  C<U> cast<U>() => new C<U>();
+}
+
 void main() {
-  Color c = .red();
+  Color color = .red();
+  C<bool> c = .foo("String").cast();
 }

pkg/front_end/testcases/dot_shorthands/static_method.dart.strong.expect

@@ -10,6 +10,16 @@ class Color extends core::Object {
   static method red() → self::Color
     return new self::Color::•(1);
 }
+class C<T extends core::Object? = dynamic> extends core::Object {
+  synthetic constructor •() → self::C<self::C::T%>
+    : super core::Object::•()
+    ;
+  static method foo<X extends core::Object? = dynamic>(self::C::foo::X% x) → self::C<self::C::foo::X%>
+    return new self::C::•<self::C::foo::X%>();
+  method cast<U extends core::Object? = dynamic>() → self::C<self::C::cast::U%>
+    return new self::C::•<self::C::cast::U%>();
+}
 static method main() → void {
-  self::Color c = self::Color::red();
+  self::Color color = self::Color::red();
+  self::C<core::bool> c = self::C::foo<core::String>("String").{self::C::cast}<core::bool>(){() → self::C<core::bool>};
 }

pkg/front_end/testcases/dot_shorthands/static_method.dart.strong.modular.expect

@@ -10,6 +10,16 @@ class Color extends core::Object {
   static method red() → self::Color
     return new self::Color::•(1);
 }
+class C<T extends core::Object? = dynamic> extends core::Object {
+  synthetic constructor •() → self::C<self::C::T%>
+    : super core::Object::•()
+    ;
+  static method foo<X extends core::Object? = dynamic>(self::C::foo::X% x) → self::C<self::C::foo::X%>
+    return new self::C::•<self::C::foo::X%>();
+  method cast<U extends core::Object? = dynamic>() → self::C<self::C::cast::U%>
+    return new self::C::•<self::C::cast::U%>();
+}
 static method main() → void {
-  self::Color c = self::Color::red();
+  self::Color color = self::Color::red();
+  self::C<core::bool> c = self::C::foo<core::String>("String").{self::C::cast}<core::bool>(){() → self::C<core::bool>};
 }

pkg/front_end/testcases/dot_shorthands/static_method.dart.strong.outline.expect

@@ -9,5 +9,13 @@ class Color extends core::Object {
   static method red() → self::Color
     ;
 }
+class C<T extends core::Object? = dynamic> extends core::Object {
+  synthetic constructor •() → self::C<self::C::T%>
+    ;
+  static method foo<X extends core::Object? = dynamic>(self::C::foo::X% x) → self::C<self::C::foo::X%>
+    ;
+  method cast<U extends core::Object? = dynamic>() → self::C<self::C::cast::U%>
+    ;
+}
 static method main() → void
   ;

pkg/front_end/testcases/dot_shorthands/static_method.dart.strong.transformed.expect

@@ -10,6 +10,16 @@ class Color extends core::Object {
   static method red() → self::Color
     return new self::Color::•(1);
 }
+class C<T extends core::Object? = dynamic> extends core::Object {
+  synthetic constructor •() → self::C<self::C::T%>
+    : super core::Object::•()
+    ;
+  static method foo<X extends core::Object? = dynamic>(self::C::foo::X% x) → self::C<self::C::foo::X%>
+    return new self::C::•<self::C::foo::X%>();
+  method cast<U extends core::Object? = dynamic>() → self::C<self::C::cast::U%>
+    return new self::C::•<self::C::cast::U%>();
+}
 static method main() → void {
-  self::Color c = self::Color::red();
+  self::Color color = self::Color::red();
+  self::C<core::bool> c = self::C::foo<core::String>("String").{self::C::cast}<core::bool>(){() → self::C<core::bool>};
 }

pkg/front_end/testcases/dot_shorthands/static_method.dart.textual_outline.expect

@@ -4,4 +4,9 @@ class Color {
   Color(this.x);
 }
 
+class C<T> {
+  static C<X> foo<X>(X x) => new C<X>();
+  C<U> cast<U>() => new C<U>();
+}
+
 void main() {}

pkg/front_end/testcases/dot_shorthands/static_method.dart.textual_outline_modelled.expect

@@ -1,3 +1,8 @@
+class C<T> {
+  C<U> cast<U>() => new C<U>();
+  static C<X> foo<X>(X x) => new C<X>();
+}
+
 class Color {
   Color(this.x);
   final int x;

tests/language/dot_shorthands/member/static_method_type_parameter_test.dart

@@ -0,0 +1,16 @@
+// Copyright (c) 2025, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// Type parameters are inferred in dot shorthand static invocations.
+
+// SharedOptions=--enable-experiment=dot-shorthands
+
+class C<T> {
+  static C<X> foo<X>(X x) => new C<X>();
+  C<U> cast<U>() => new C<U>();
+}
+
+void main() {
+  C<bool> c = .foo("String").cast();
+}