commit a7b0f5108d2938f03eda39bdd72e05135f07d76f
author Paul Berry <paulberry@google.com> Fri Mar 26 00:29:24 2021 +0000
committer commit-bot@chromium.org <commit-bot@chromium.org> Fri Mar 26 00:29:24 2021 +0000
tree 164f10550087a7910000994c8190d347270663d4
parent 79bf4f33aecbd9025f573396e384cbe5d235e11b

Flow analysis: implement "why not promoted" logic for compound assignments.

Bug: https://github.com/dart-lang/sdk/issues/44898
Change-Id: I57a2c62b8450c313887b516d6fe2ef85fdd0d92b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/193084
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Commit-Queue: Paul Berry <paulberry@google.com>

pkg/_fe_analyzer_shared/test/flow_analysis/why_not_promoted/data/argument_type_not_assignable_nullability_error.dart

diff --git a/pkg/_fe_analyzer_shared/test/flow_analysis/why_not_promoted/data/argument_type_not_assignable_nullability_error.dart b/pkg/_fe_analyzer_shared/test/flow_analysis/why_not_promoted/data/argument_type_not_assignable_nullability_error.dart
index 8f705df..e83ebea 100644
--- a/pkg/_fe_analyzer_shared/test/flow_analysis/why_not_promoted/data/argument_type_not_assignable_nullability_error.dart
+++ b/pkg/_fe_analyzer_shared/test/flow_analysis/why_not_promoted/data/argument_type_not_assignable_nullability_error.dart
@@ -389,3 +389,15 @@
       null: null
   });
 }
+
+class C26 {
+  int? bad;
+}
+
+compoundAssignmentRhs(C26 c) {
+  int i = 0;
+  if (c.bad == null) return;
+  i +=
+      /*analyzer.notPromoted(propertyNotPromoted(target: member:C26.bad, type: int?))*/ c
+          . /*cfe.notPromoted(propertyNotPromoted(target: member:C26.bad, type: int?))*/ bad;
+}

pkg/analyzer/lib/src/dart/resolver/assignment_expression_resolver.dart

diff --git a/pkg/analyzer/lib/src/dart/resolver/assignment_expression_resolver.dart b/pkg/analyzer/lib/src/dart/resolver/assignment_expression_resolver.dart
index a3a966c..4c05164 100644
--- a/pkg/analyzer/lib/src/dart/resolver/assignment_expression_resolver.dart
+++ b/pkg/analyzer/lib/src/dart/resolver/assignment_expression_resolver.dart
@@ -248,6 +248,11 @@
       assignedType,
       whyNotPromoted: operator == TokenType.EQ ? whyNotPromoted : null,
     );
+    if (operator != TokenType.EQ &&
+        operator != TokenType.QUESTION_QUESTION_EQ) {
+      _resolver.checkForArgumentTypeNotAssignableForArgument(node.rightHandSide,
+          whyNotPromoted: whyNotPromoted);
+    }
   }
 
   void _setRhsContext(AssignmentExpressionImpl node, DartType leftType,

pkg/analyzer/lib/src/generated/error_verifier.dart

diff --git a/pkg/analyzer/lib/src/generated/error_verifier.dart b/pkg/analyzer/lib/src/generated/error_verifier.dart
index e8136ea..16387ea 100644
--- a/pkg/analyzer/lib/src/generated/error_verifier.dart
+++ b/pkg/analyzer/lib/src/generated/error_verifier.dart
@@ -345,12 +345,6 @@
   void visitAssignmentExpression(AssignmentExpression node) {
     TokenType operatorType = node.operator.type;
     Expression lhs = node.leftHandSide;
-    Expression rhs = node.rightHandSide;
-    if (operatorType == TokenType.EQ ||
-        operatorType == TokenType.QUESTION_QUESTION_EQ) {
-    } else {
-      checkForArgumentTypeNotAssignableForArgument(rhs);
-    }
     if (operatorType == TokenType.QUESTION_QUESTION_EQ) {
       _checkForDeadNullCoalesce(node.readType as TypeImpl, node.rightHandSide);
     }