[cfe] Add work-around for partial inference

Type arguments in object patterns are only partially inferred
and leads to crashing because of unknown types.

This adds a work-around to fully infer the type arguments while
waiting for the resolution of language issue #2770.

Change-Id: I2af228b472414f0077c005105c971a4f84189e07
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/280082
Reviewed-by: Chloe Stefantsova <[email protected]>
Commit-Queue: Johnni Winther <[email protected]>

Author: johnniwinther

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

@@ -10012,6 +10012,12 @@ class InferenceVisitorImpl extends InferenceVisitorBase
             typeParametersToInfer, matchedType, libraryBuilder.library);
     List<DartType> inferredTypes = typeSchemaEnvironment.partialInfer(
         gatherer, typeParametersToInfer, null, libraryBuilder.library);
+
+    // TODO(johnniwinther): Remove this work-around once language issue #2770
+    // has been resolved.
+    inferredTypes = typeSchemaEnvironment.upwardsInfer(
+        gatherer, typeParametersToInfer, inferredTypes, libraryBuilder.library);
+
     Substitution substitution =
         Substitution.fromPairs(typeParametersToInfer, inferredTypes);
     return substitution.substituteType(typeToInfer);

pkg/front_end/testcases/patterns/language_issue2770.dart

@@ -0,0 +1,19 @@
+// Copyright (c) 2023, 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.
+
+class Class<T extends Object> {
+  T field;
+  Class(this.field);
+}
+
+method1(Object object) {
+  if (object case Class(:var field)) {
+    print(field);
+  }
+}
+
+main() {
+  method1(new Class(42));
+  method1(new Class('foo'));
+}

pkg/front_end/testcases/patterns/language_issue2770.dart.strong.expect

@@ -0,0 +1,23 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+
+class Class<T extends core::Object> extends core::Object {
+  covariant-by-class field self::Class::T field;
+  constructor •(self::Class::T field) → self::Class<self::Class::T>
+    : self::Class::field = field, super core::Object::•()
+    ;
+}
+static method method1(core::Object object) → dynamic {
+  {
+    core::Object field;
+    final core::Object #0#0 = object;
+    if(#0#0 is{ForNonNullableByDefault} self::Class<core::Object> && (let final dynamic #t1 = field = #0#0{self::Class<core::Object>}.{self::Class::field}{core::Object} in true)) {
+      core::print(field);
+    }
+  }
+}
+static method main() → dynamic {
+  self::method1(new self::Class::•<core::int>(42));
+  self::method1(new self::Class::•<core::String>("foo"));
+}

pkg/front_end/testcases/patterns/language_issue2770.dart.strong.transformed.expect

@@ -0,0 +1,23 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+
+class Class<T extends core::Object> extends core::Object {
+  covariant-by-class field self::Class::T field;
+  constructor •(self::Class::T field) → self::Class<self::Class::T>
+    : self::Class::field = field, super core::Object::•()
+    ;
+}
+static method method1(core::Object object) → dynamic {
+  {
+    core::Object field;
+    final core::Object #0#0 = object;
+    if(#0#0 is{ForNonNullableByDefault} self::Class<core::Object> && (let final core::Object #t1 = field = #0#0{self::Class<core::Object>}.{self::Class::field}{core::Object} in true)) {
+      core::print(field);
+    }
+  }
+}
+static method main() → dynamic {
+  self::method1(new self::Class::•<core::int>(42));
+  self::method1(new self::Class::•<core::String>("foo"));
+}

pkg/front_end/testcases/patterns/language_issue2770.dart.textual_outline.expect

@@ -0,0 +1,7 @@
+class Class<T extends Object> {
+  T field;
+  Class(this.field);
+}
+
+method1(Object object) {}
+main() {}

pkg/front_end/testcases/patterns/language_issue2770.dart.textual_outline_modelled.expect

@@ -0,0 +1,7 @@
+class Class<T extends Object> {
+  Class(this.field);
+  T field;
+}
+
+main() {}
+method1(Object object) {}

pkg/front_end/testcases/patterns/language_issue2770.dart.weak.expect

@@ -0,0 +1,23 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+
+class Class<T extends core::Object> extends core::Object {
+  covariant-by-class field self::Class::T field;
+  constructor •(self::Class::T field) → self::Class<self::Class::T>
+    : self::Class::field = field, super core::Object::•()
+    ;
+}
+static method method1(core::Object object) → dynamic {
+  {
+    core::Object field;
+    final core::Object #0#0 = object;
+    if(#0#0 is{ForNonNullableByDefault} self::Class<core::Object> && (let final dynamic #t1 = field = #0#0{self::Class<core::Object>}.{self::Class::field}{core::Object} in true)) {
+      core::print(field);
+    }
+  }
+}
+static method main() → dynamic {
+  self::method1(new self::Class::•<core::int>(42));
+  self::method1(new self::Class::•<core::String>("foo"));
+}

pkg/front_end/testcases/patterns/language_issue2770.dart.weak.modular.expect

@@ -0,0 +1,23 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+
+class Class<T extends core::Object> extends core::Object {
+  covariant-by-class field self::Class::T field;
+  constructor •(self::Class::T field) → self::Class<self::Class::T>
+    : self::Class::field = field, super core::Object::•()
+    ;
+}
+static method method1(core::Object object) → dynamic {
+  {
+    core::Object field;
+    final core::Object #0#0 = object;
+    if(#0#0 is{ForNonNullableByDefault} self::Class<core::Object> && (let final dynamic #t1 = field = #0#0{self::Class<core::Object>}.{self::Class::field}{core::Object} in true)) {
+      core::print(field);
+    }
+  }
+}
+static method main() → dynamic {
+  self::method1(new self::Class::•<core::int>(42));
+  self::method1(new self::Class::•<core::String>("foo"));
+}

pkg/front_end/testcases/patterns/language_issue2770.dart.weak.outline.expect

@@ -0,0 +1,13 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+
+class Class<T extends core::Object> extends core::Object {
+  covariant-by-class field self::Class::T field;
+  constructor •(self::Class::T field) → self::Class<self::Class::T>
+    ;
+}
+static method method1(core::Object object) → dynamic
+  ;
+static method main() → dynamic
+  ;

pkg/front_end/testcases/patterns/language_issue2770.dart.weak.transformed.expect

@@ -0,0 +1,23 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+
+class Class<T extends core::Object> extends core::Object {
+  covariant-by-class field self::Class::T field;
+  constructor •(self::Class::T field) → self::Class<self::Class::T>
+    : self::Class::field = field, super core::Object::•()
+    ;
+}
+static method method1(core::Object object) → dynamic {
+  {
+    core::Object field;
+    final core::Object #0#0 = object;
+    if(#0#0 is{ForNonNullableByDefault} self::Class<core::Object> && (let final core::Object #t1 = field = #0#0{self::Class<core::Object>}.{self::Class::field}{core::Object} in true)) {
+      core::print(field);
+    }
+  }
+}
+static method main() → dynamic {
+  self::method1(new self::Class::•<core::int>(42));
+  self::method1(new self::Class::•<core::String>("foo"));
+}