[model] Only infer first required positional parameter in setters

This CL makes sure that only the first required positional parameter
is inferred in setters. Optional positional and named parameters,
which are erroneous in the case of setters, aren't inferred. That
prevents reporting of some cascading errors.

Change-Id: If89628adf542a325aa7320557c131abb7987a687
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/426040
Commit-Queue: Chloe Stefantsova <[email protected]>
Reviewed-by: Johnni Winther <[email protected]>

Author: chloestefantsova

pkg/front_end/lib/src/kernel/hierarchy/members_node.dart

@@ -392,7 +392,20 @@ class ClassMembersNodeBuilder extends MembersNodeBuilder {
       // Erroneous case.
       return;
     }
-    FormalParameterBuilder parameter = formals.first;
+
+    // Only infer the parameter type if it's the first required positional.
+    FormalParameterBuilder? parameter;
+    for (FormalParameterBuilder formal in formals) {
+      if (formal.isRequiredPositional) {
+        parameter = formal;
+        break;
+      }
+    }
+    if (parameter == null) {
+      // Erroneous case.
+      return;
+    }
+
     if (parameter.type is InferableTypeBuilder) {
       DartType? inferredType;
 

pkg/front_end/testcases/general/issue54006.dart.strong.expect

@@ -59,16 +59,6 @@ library;
 //   get field(a) => 0;
 //            ^
 //
-// pkg/front_end/testcases/general/issue54006.dart:27:14: Error: The parameter 'a' can't have a value of 'null' because of its type 'int', but the implicit default value is 'null'.
-// Try adding either an explicit non-'null' default value or the 'required' modifier.
-//   set field([a]) {}
-//              ^
-//
-// pkg/front_end/testcases/general/issue54006.dart:32:14: Error: The parameter 'a' can't have a value of 'null' because of its type 'int', but the implicit default value is 'null'.
-// Try adding either an explicit non-'null' default value or the 'required' modifier.
-//   set field({a}) {}
-//              ^
-//
 // pkg/front_end/testcases/general/issue54006.dart:12:13: Error: Expected a function body or '=>'.
 // Try adding {}.
 //   set field = 0;
@@ -161,7 +151,7 @@ class E extends core::Object implements self::A {
   set field([a]) {}
            ^";
     {
-      core::int a = null;
+      dynamic a = null;
       {}
     }
   }
@@ -177,7 +167,7 @@ class F extends core::Object implements self::A {
   set field({a}) {}
            ^";
     {
-      core::int a = null;
+      dynamic a = null;
       {}
     }
   }

pkg/front_end/testcases/general/issue54006.dart.strong.modular.expect

@@ -59,16 +59,6 @@ library;
 //   get field(a) => 0;
 //            ^
 //
-// pkg/front_end/testcases/general/issue54006.dart:27:14: Error: The parameter 'a' can't have a value of 'null' because of its type 'int', but the implicit default value is 'null'.
-// Try adding either an explicit non-'null' default value or the 'required' modifier.
-//   set field([a]) {}
-//              ^
-//
-// pkg/front_end/testcases/general/issue54006.dart:32:14: Error: The parameter 'a' can't have a value of 'null' because of its type 'int', but the implicit default value is 'null'.
-// Try adding either an explicit non-'null' default value or the 'required' modifier.
-//   set field({a}) {}
-//              ^
-//
 // pkg/front_end/testcases/general/issue54006.dart:12:13: Error: Expected a function body or '=>'.
 // Try adding {}.
 //   set field = 0;
@@ -161,7 +151,7 @@ class E extends core::Object implements self::A {
   set field([a]) {}
            ^";
     {
-      core::int a = null;
+      dynamic a = null;
       {}
     }
   }
@@ -177,7 +167,7 @@ class F extends core::Object implements self::A {
   set field({a}) {}
            ^";
     {
-      core::int a = null;
+      dynamic a = null;
       {}
     }
   }

pkg/front_end/testcases/general/issue54006.dart.strong.outline.expect

@@ -59,16 +59,6 @@ library;
 //   get field(a) => 0;
 //            ^
 //
-// pkg/front_end/testcases/general/issue54006.dart:27:14: Error: The parameter 'a' can't have a value of 'null' because of its type 'int', but the implicit default value is 'null'.
-// Try adding either an explicit non-'null' default value or the 'required' modifier.
-//   set field([a]) {}
-//              ^
-//
-// pkg/front_end/testcases/general/issue54006.dart:32:14: Error: The parameter 'a' can't have a value of 'null' because of its type 'int', but the implicit default value is 'null'.
-// Try adding either an explicit non-'null' default value or the 'required' modifier.
-//   set field({a}) {}
-//              ^
-//
 import self as self;
 import "dart:core" as core;
 

pkg/front_end/testcases/general/issue54006.dart.strong.transformed.expect

@@ -59,16 +59,6 @@ library;
 //   get field(a) => 0;
 //            ^
 //
-// pkg/front_end/testcases/general/issue54006.dart:27:14: Error: The parameter 'a' can't have a value of 'null' because of its type 'int', but the implicit default value is 'null'.
-// Try adding either an explicit non-'null' default value or the 'required' modifier.
-//   set field([a]) {}
-//              ^
-//
-// pkg/front_end/testcases/general/issue54006.dart:32:14: Error: The parameter 'a' can't have a value of 'null' because of its type 'int', but the implicit default value is 'null'.
-// Try adding either an explicit non-'null' default value or the 'required' modifier.
-//   set field({a}) {}
-//              ^
-//
 // pkg/front_end/testcases/general/issue54006.dart:12:13: Error: Expected a function body or '=>'.
 // Try adding {}.
 //   set field = 0;
@@ -161,7 +151,7 @@ class E extends core::Object implements self::A {
   set field([a]) {}
            ^";
     {
-      core::int a = null;
+      dynamic a = null;
       {}
     }
   }
@@ -177,7 +167,7 @@ class F extends core::Object implements self::A {
   set field({a}) {}
            ^";
     {
-      core::int a = null;
+      dynamic a = null;
       {}
     }
   }