fix: joining if-cases

Closes https://github.com/dart-lang/sdk/pull/56920

GitOrigin-RevId: 4e9075cacc6d4af73775aae1d42ee6fde4377b4e
Change-Id: I8873082cc993de8b65191d02537f8199dd4fc68c
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/390632
Commit-Queue: Phil Quitslund <pquitslund@google.com>
Commit-Queue: Brian Wilkerson <brianwilkerson@google.com>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Reviewed-by: Phil Quitslund <pquitslund@google.com>

pkg/analysis_server/lib/src/services/correction/dart/join_if_with_inner.dart

@@ -42,6 +42,12 @@ class JoinIfWithInner extends ResolvedCorrectionProducer {
     if (innerIfStatement.elseStatement != null) {
       return;
     }
+
+    // If inner is if-case, we cannot join them.
+    if (innerIfStatement.caseClause != null) {
+      return;
+    }
+
     // prepare environment
     var prefix = utils.getNodePrefix(targetIfStatement);
     // merge conditions
@@ -55,7 +61,30 @@ class JoinIfWithInner extends ResolvedCorrectionProducer {
     if (innerCondition.shouldWrapParenthesisBeforeAnd) {
       innerConditionSource = '($innerConditionSource)';
     }
+
     var condition = '$targetConditionSource && $innerConditionSource';
+
+    // If outer is if-case.
+    var outerCaseClause = targetIfStatement.caseClause;
+    if (outerCaseClause != null) {
+      var casePattern = outerCaseClause.guardedPattern.pattern;
+      var caseWhenExpression =
+          outerCaseClause.guardedPattern.whenClause?.expression;
+
+      if (caseWhenExpression != null) {
+        var caseWhenSource = '$caseWhenExpression';
+        if (caseWhenExpression.shouldWrapParenthesisBeforeAnd) {
+          caseWhenSource = '($caseWhenSource)';
+        }
+
+        condition =
+            '$targetConditionSource case $casePattern when $caseWhenSource && $innerConditionSource';
+      } else {
+        condition =
+            '$targetConditionSource case $casePattern when $innerConditionSource';
+      }
+    }
+
     // replace target "if" statement
     var innerThenStatement = innerIfStatement.thenStatement;
     var innerThenStatements = getStatements(innerThenStatement);

pkg/analysis_server/lib/src/services/correction/dart/join_if_with_outer.dart

@@ -48,6 +48,12 @@ class JoinIfWithOuter extends ResolvedCorrectionProducer {
     if (outerIfStatement.elseStatement != null) {
       return;
     }
+
+    // If target (inner) is if-case, we cannot join them.
+    if (targetIfStatement.caseClause != null) {
+      return;
+    }
+
     // prepare environment
     var prefix = utils.getNodePrefix(outerIfStatement);
     // merge conditions
@@ -61,7 +67,30 @@ class JoinIfWithOuter extends ResolvedCorrectionProducer {
     if (outerCondition.shouldWrapParenthesisBeforeAnd) {
       outerConditionSource = '($outerConditionSource)';
     }
+
     var condition = '$outerConditionSource && $targetConditionSource';
+
+    // If outer is if-case.
+    var outerCaseClause = outerIfStatement.caseClause;
+    if (outerCaseClause != null) {
+      var casePattern = outerCaseClause.guardedPattern.pattern;
+      var caseWhenExpression =
+          outerCaseClause.guardedPattern.whenClause?.expression;
+
+      if (caseWhenExpression != null) {
+        var caseWhenSource = '$caseWhenExpression';
+        if (caseWhenExpression.shouldWrapParenthesisBeforeAnd) {
+          caseWhenSource = '($caseWhenSource)';
+        }
+
+        condition =
+            '$outerConditionSource case $casePattern when $caseWhenSource && $targetConditionSource';
+      } else {
+        condition =
+            '$outerConditionSource case $casePattern when $targetConditionSource';
+      }
+    }
+
     // replace outer "if" statement
     var targetThenStatement = targetIfStatement.thenStatement;
     var targetThenStatements = getStatements(targetThenStatement);

pkg/analysis_server/test/src/services/correction/assist/join_if_with_inner_test.dart

@@ -19,6 +19,19 @@ class JoinIfWithInnerTest extends AssistProcessorTest {
   @override
   AssistKind get kind => DartAssistKind.JOIN_IF_WITH_INNER;
 
+  Future<void> test_bothOuterAndInnerAreIfCase() async {
+    await resolveTestCode('''
+void f(Object? p) {
+  if (p case final v?) {
+    if (v case final int x) {
+      print(0);
+    }
+  }
+}
+''');
+    await assertNoAssistAt('if (p');
+  }
+
   Future<void> test_conditionAndOr() async {
     await resolveTestCode('''
 void f() {
@@ -78,6 +91,120 @@ void f() {
 ''');
   }
 
+  Future<void> test_ifCaseAddWhen() async {
+    await resolveTestCode('''
+void f(Object? p) {
+  if (p case final int v) {
+    if (v == 5) {
+      print(0);
+    }
+  }
+}
+''');
+    await assertHasAssistAt('if (p', '''
+void f(Object? p) {
+  if (p case final int v when v == 5) {
+    print(0);
+  }
+}
+''');
+  }
+
+  Future<void> test_ifCaseAddWhenUnrelated() async {
+    await resolveTestCode('''
+void f(Object? p, Object? q) {
+  if (p case final int v) {
+    if (q != null) {
+      print(0);
+    }
+  }
+}
+''');
+    await assertHasAssistAt('if (p', '''
+void f(Object? p, Object? q) {
+  if (p case final int v when q != null) {
+    print(0);
+  }
+}
+''');
+  }
+
+  Future<void> test_ifCaseAppendWhen() async {
+    await resolveTestCode('''
+void f(Object? p) {
+  if (p case final int v when v.isOdd) {
+    if (v == 5) {
+      print(0);
+    }
+  }
+}
+''');
+    await assertHasAssistAt('if (p', '''
+void f(Object? p) {
+  if (p case final int v when v.isOdd && v == 5) {
+    print(0);
+  }
+}
+''');
+  }
+
+  Future<void> test_ifCaseAppendWhenWithParenthesisBoth() async {
+    await resolveTestCode('''
+void f(Object? p) {
+  if (p case final int v when v.isOdd || v > 3) {
+    if (v == 5 || v != 6) {
+      print(0);
+    }
+  }
+}
+''');
+    await assertHasAssistAt('if (p', '''
+void f(Object? p) {
+  if (p case final int v when (v.isOdd || v > 3) && (v == 5 || v != 6)) {
+    print(0);
+  }
+}
+''');
+  }
+
+  Future<void> test_ifCaseAppendWhenWithParenthesisInner() async {
+    await resolveTestCode('''
+void f(Object? p) {
+  if (p case final int v when v.isOdd) {
+    if (v == 5 || v != 3) {
+      print(0);
+    }
+  }
+}
+''');
+    await assertHasAssistAt('if (p', '''
+void f(Object? p) {
+  if (p case final int v when v.isOdd && (v == 5 || v != 3)) {
+    print(0);
+  }
+}
+''');
+  }
+
+  Future<void> test_ifCaseAppendWhenWithParenthesisOuter() async {
+    await resolveTestCode('''
+void f(Object? p) {
+  if (p case final int v when v.isOdd || v != 3) {
+    if (v == 5) {
+      print(0);
+    }
+  }
+}
+''');
+    await assertHasAssistAt('if (p', '''
+void f(Object? p) {
+  if (p case final int v when (v.isOdd || v != 3) && v == 5) {
+    print(0);
+  }
+}
+''');
+  }
+
   Future<void> test_innerNotIf() async {
     await resolveTestCode('''
 void f() {

pkg/analysis_server/test/src/services/correction/assist/join_if_with_outer_test.dart

@@ -19,6 +19,19 @@ class JoinIfWithOuterTest extends AssistProcessorTest {
   @override
   AssistKind get kind => DartAssistKind.JOIN_IF_WITH_OUTER;
 
+  Future<void> test_bothOuterAndInnerAreIfCase() async {
+    await resolveTestCode('''
+void f(Object? p) {
+  if (p case final v?) {
+    if (v case final int x) {
+      print(x);
+    }
+  }
+}
+''');
+    await assertNoAssistAt('if (v');
+  }
+
   Future<void> test_conditionAndOr() async {
     await resolveTestCode('''
 void f() {
@@ -78,6 +91,120 @@ void f() {
 ''');
   }
 
+  Future<void> test_ifCaseAddWhen() async {
+    await resolveTestCode('''
+void f(Object? p) {
+  if (p case final int v) {
+    if (v == 5) {
+      print(0);
+    }
+  }
+}
+''');
+    await assertHasAssistAt('if (v == 5', '''
+void f(Object? p) {
+  if (p case final int v when v == 5) {
+    print(0);
+  }
+}
+''');
+  }
+
+  Future<void> test_ifCaseAddWhenUnrelated() async {
+    await resolveTestCode('''
+void f(Object? p, Object? q) {
+  if (p case final int v) {
+    if (q != null) {
+      print(0);
+    }
+  }
+}
+''');
+    await assertHasAssistAt('if (q != null', '''
+void f(Object? p, Object? q) {
+  if (p case final int v when q != null) {
+    print(0);
+  }
+}
+''');
+  }
+
+  Future<void> test_ifCaseAppendWhen() async {
+    await resolveTestCode('''
+void f(Object? p) {
+  if (p case final int v when v.isOdd) {
+    if (v == 5) {
+      print(0);
+    }
+  }
+}
+''');
+    await assertHasAssistAt('if (v == 5', '''
+void f(Object? p) {
+  if (p case final int v when v.isOdd && v == 5) {
+    print(0);
+  }
+}
+''');
+  }
+
+  Future<void> test_ifCaseAppendWhenWithParenthesisBoth() async {
+    await resolveTestCode('''
+void f(Object? p) {
+  if (p case final int v when v.isOdd || v > 3) {
+    if (v == 5 || v != 6) {
+      print(0);
+    }
+  }
+}
+''');
+    await assertHasAssistAt('if (v', '''
+void f(Object? p) {
+  if (p case final int v when (v.isOdd || v > 3) && (v == 5 || v != 6)) {
+    print(0);
+  }
+}
+''');
+  }
+
+  Future<void> test_ifCaseAppendWhenWithParenthesisInner() async {
+    await resolveTestCode('''
+void f(Object? p) {
+  if (p case final int v when v.isOdd) {
+    if (v == 5 || v != 3) {
+      print(0);
+    }
+  }
+}
+''');
+    await assertHasAssistAt('if (v', '''
+void f(Object? p) {
+  if (p case final int v when v.isOdd && (v == 5 || v != 3)) {
+    print(0);
+  }
+}
+''');
+  }
+
+  Future<void> test_ifCaseAppendWhenWithParenthesisOuter() async {
+    await resolveTestCode('''
+void f(Object? p) {
+  if (p case final int v when v.isOdd || v != 3) {
+    if (v == 5) {
+      print(0);
+    }
+  }
+}
+''');
+    await assertHasAssistAt('if (v', '''
+void f(Object? p) {
+  if (p case final int v when (v.isOdd || v != 3) && v == 5) {
+    print(0);
+  }
+}
+''');
+  }
+
   Future<void> test_onCondition() async {
     await resolveTestCode('''
 void f() {