Additional test cases in support of record/variable pattern disambigu…

…ation.

Two of these tests (`recordPattern_nullable_beforeAs` and
`recordPattern_nullable_beforeWhen`) verify that the fix for #52439
(Destructuring with explicit type of nullable record is a parsing
error), which causes `(...)? identifier` to be recognized as a
variable pattern, doesn't get confused by the pseudo-identifiers `as`
and `when`, and so it continues to correctly parse `(...)? as ...` as a
cast pattern and `(...)? when ...` as a guarded pattern.

The other two tests (`recordPattern_nonNullable_beforeAs` and
`recordPattern_nonNullable_beforeWhen`) verify that `(...) as ...` and
`(...) when ...` are parsed correctly. These forms were never broken,
but they were not well tested either.

Bug: #52439
Change-Id: I866e1c7a6a8e47e0cd91a1a77654405f395b50da
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/305844
Reviewed-by: Jens Johansen <jensj@google.com>
Commit-Queue: Paul Berry <paulberry@google.com>

pkg/analyzer/test/generated/patterns_parser_test.dart

@@ -8509,6 +8509,122 @@ NullCheckPattern
 ''');
   }
 
+  test_recordPattern_nonNullable_beforeAs() {
+    _parse('''
+void f(x) {
+  switch (x) {
+    case (_,) as (Object,):
+  }
+}
+''');
+    var node = findNode.singleGuardedPattern;
+    assertParsedNodeText(node, r'''
+GuardedPattern
+  pattern: CastPattern
+    pattern: RecordPattern
+      leftParenthesis: (
+      fields
+        PatternField
+          pattern: WildcardPattern
+            name: _
+      rightParenthesis: )
+    asToken: as
+    type: RecordTypeAnnotation
+      leftParenthesis: (
+      positionalFields
+        RecordTypeAnnotationPositionalField
+          type: NamedType
+            name: Object
+      rightParenthesis: )
+''');
+  }
+
+  test_recordPattern_nonNullable_beforeWhen() {
+    _parse('''
+void f(x) {
+  switch (x) {
+    case (_,) when true:
+  }
+}
+''');
+    var node = findNode.singleGuardedPattern;
+    assertParsedNodeText(node, r'''
+GuardedPattern
+  pattern: RecordPattern
+    leftParenthesis: (
+    fields
+      PatternField
+        pattern: WildcardPattern
+          name: _
+    rightParenthesis: )
+  whenClause: WhenClause
+    whenKeyword: when
+    expression: BooleanLiteral
+      literal: true
+''');
+  }
+
+  test_recordPattern_nullable_beforeAs() {
+    _parse('''
+void f(x) {
+  switch (x) {
+    case (_,)? as (Object,):
+  }
+}
+''', errors: [
+      error(ParserErrorCode.INVALID_INSIDE_UNARY_PATTERN, 36, 5),
+    ]);
+    var node = findNode.singleGuardedPattern;
+    assertParsedNodeText(node, r'''
+GuardedPattern
+  pattern: CastPattern
+    pattern: NullCheckPattern
+      pattern: RecordPattern
+        leftParenthesis: (
+        fields
+          PatternField
+            pattern: WildcardPattern
+              name: _
+        rightParenthesis: )
+      operator: ?
+    asToken: as
+    type: RecordTypeAnnotation
+      leftParenthesis: (
+      positionalFields
+        RecordTypeAnnotationPositionalField
+          type: NamedType
+            name: Object
+      rightParenthesis: )
+''');
+  }
+
+  test_recordPattern_nullable_beforeWhen() {
+    _parse('''
+void f(x) {
+  switch (x) {
+    case (_,)? when true:
+  }
+}
+''');
+    var node = findNode.singleGuardedPattern;
+    assertParsedNodeText(node, r'''
+GuardedPattern
+  pattern: NullCheckPattern
+    pattern: RecordPattern
+      leftParenthesis: (
+      fields
+        PatternField
+          pattern: WildcardPattern
+            name: _
+      rightParenthesis: )
+    operator: ?
+  whenClause: WhenClause
+    whenKeyword: when
+    expression: BooleanLiteral
+      literal: true
+''');
+  }
+
   test_recordTypedVariablePattern_nonNullable_beforeAnd() {
     _parse('''
 void f(x) {

pkg/front_end/parser_testcases/patterns/recordPattern_nonNullable_beforeAs.dart

@@ -0,0 +1,5 @@
+void f(x) {
+  switch (x) {
+    case (_,) as (Object,):
+  }
+}

pkg/front_end/parser_testcases/patterns/recordPattern_nonNullable_beforeAs.dart.expect

@@ -0,0 +1,58 @@
+beginCompilationUnit(void)
+  beginMetadataStar(void)
+  endMetadataStar(0)
+  beginTopLevelMember(void)
+    beginTopLevelMethod(, null, null)
+      handleVoidKeyword(void)
+      handleIdentifier(f, topLevelFunctionDeclaration)
+      handleNoTypeVariables(()
+      beginFormalParameters((, MemberKind.TopLevelMethod)
+        beginMetadataStar(x)
+        endMetadataStar(0)
+        beginFormalParameter(x, MemberKind.TopLevelMethod, null, null, null)
+          handleNoType(()
+          handleIdentifier(x, formalParameterDeclaration)
+          handleFormalParameterWithoutValue())
+        endFormalParameter(null, null, null, x, null, null, FormalParameterKind.requiredPositional, MemberKind.TopLevelMethod)
+      endFormalParameters(1, (, ), MemberKind.TopLevelMethod)
+      handleAsyncModifier(null, null)
+      beginBlockFunctionBody({)
+        beginSwitchStatement(switch)
+          handleIdentifier(x, expression)
+          handleNoTypeArguments())
+          handleNoArguments())
+          handleSend(x, ))
+          handleParenthesizedCondition((, null, null)
+          beginSwitchBlock({)
+            beginCaseExpression(case)
+              beginPattern(case)
+                beginPattern(()
+                  handleNoType(_)
+                  handleWildcardPattern(null, _)
+                endPattern(_)
+                handlePatternField(null)
+                handleRecordPattern((, 1)
+                beginAsOperatorType(as)
+                  beginRecordType(()
+                    beginRecordTypeEntry()
+                      beginMetadataStar(Object)
+                      endMetadataStar(0)
+                      handleIdentifier(Object, typeReference)
+                      handleNoTypeArguments(,)
+                      handleType(Object, null)
+                      handleNoName(,)
+                    endRecordTypeEntry()
+                  endRecordType((, null, 1, false)
+                endAsOperatorType(as)
+                handleCastPattern(as)
+              endPattern())
+              handleSwitchCaseNoWhenClause())
+            endCaseExpression(case, null, :)
+            beginSwitchCase(0, 1, case)
+            endSwitchCase(0, 1, null, null, 0, case, })
+          endSwitchBlock(1, {, })
+        endSwitchStatement(switch, })
+      endBlockFunctionBody(1, {, })
+    endTopLevelMethod(void, null, })
+  endTopLevelDeclaration()
+endCompilationUnit(1, )

pkg/front_end/parser_testcases/patterns/recordPattern_nonNullable_beforeAs.dart.intertwined.expect

@@ -0,0 +1,116 @@
+parseUnit(void)
+  skipErrorTokens(void)
+  listener: beginCompilationUnit(void)
+  syntheticPreviousToken(void)
+  parseTopLevelDeclarationImpl(, Instance of 'DirectiveContext')
+    parseMetadataStar()
+      listener: beginMetadataStar(void)
+      listener: endMetadataStar(0)
+    parseTopLevelMemberImpl()
+      listener: beginTopLevelMember(void)
+      parseTopLevelMethod(, null, null, , Instance of 'VoidType', null, f, false)
+        listener: beginTopLevelMethod(, null, null)
+        listener: handleVoidKeyword(void)
+        ensureIdentifierPotentiallyRecovered(void, topLevelFunctionDeclaration, false)
+          listener: handleIdentifier(f, topLevelFunctionDeclaration)
+        parseMethodTypeVar(f)
+          listener: handleNoTypeVariables(()
+        parseGetterOrFormalParameters(f, f, false, MemberKind.TopLevelMethod)
+          parseFormalParameters(f, MemberKind.TopLevelMethod)
+            parseFormalParametersRest((, MemberKind.TopLevelMethod)
+              listener: beginFormalParameters((, MemberKind.TopLevelMethod)
+              parseFormalParameter((, FormalParameterKind.requiredPositional, MemberKind.TopLevelMethod)
+                parseMetadataStar(()
+                  listener: beginMetadataStar(x)
+                  listener: endMetadataStar(0)
+                listener: beginFormalParameter(x, MemberKind.TopLevelMethod, null, null, null)
+                listener: handleNoType(()
+                ensureIdentifier((, formalParameterDeclaration)
+                  listener: handleIdentifier(x, formalParameterDeclaration)
+                listener: handleFormalParameterWithoutValue())
+                listener: endFormalParameter(null, null, null, x, null, null, FormalParameterKind.requiredPositional, MemberKind.TopLevelMethod)
+              listener: endFormalParameters(1, (, ), MemberKind.TopLevelMethod)
+        parseAsyncModifierOpt())
+          listener: handleAsyncModifier(null, null)
+          inPlainSync()
+        parseFunctionBody(), false, false)
+          listener: beginBlockFunctionBody({)
+          notEofOrValue(}, switch)
+          parseStatement({)
+            parseStatementX({)
+              parseSwitchStatement({)
+                listener: beginSwitchStatement(switch)
+                ensureParenthesizedCondition(switch, allowCase: false)
+                  parseExpressionInParenthesisRest((, allowCase: false)
+                    parseExpression(()
+                      looksLikeOuterPatternEquals(()
+                        skipOuterPattern(()
+                          skipObjectPatternRest(x)
+                      parsePrecedenceExpression((, 1, true, ConstantPatternContext.none)
+                        parseUnaryExpression((, true, ConstantPatternContext.none)
+                          parsePrimary((, expression, ConstantPatternContext.none)
+                            parseSendOrFunctionLiteral((, expression, ConstantPatternContext.none)
+                              parseSend((, expression, ConstantPatternContext.none)
+                                isNextIdentifier(()
+                                ensureIdentifier((, expression)
+                                  listener: handleIdentifier(x, expression)
+                                listener: handleNoTypeArguments())
+                                parseArgumentsOpt(x)
+                                  listener: handleNoArguments())
+                                listener: handleSend(x, ))
+                    ensureCloseParen(x, ()
+                    listener: handleParenthesizedCondition((, null, null)
+                parseSwitchBlock())
+                  ensureBlock(), null, switch statement)
+                  listener: beginSwitchBlock({)
+                  notEofOrValue(}, case)
+                  peekPastLabels(case)
+                  listener: beginCaseExpression(case)
+                  parsePattern(case, PatternContext.matching, precedence: 1)
+                    listener: beginPattern(case)
+                    parsePrimaryPattern(case, PatternContext.matching)
+                      parseParenthesizedPatternOrRecordPattern(case, PatternContext.matching)
+                        parsePattern((, PatternContext.matching, precedence: 1)
+                          listener: beginPattern(()
+                          parsePrimaryPattern((, PatternContext.matching)
+                            parseVariablePattern((, PatternContext.matching, typeInfo: Instance of 'NoType')
+                              listener: handleNoType(_)
+                              listener: handleWildcardPattern(null, _)
+                          listener: endPattern(_)
+                        listener: handlePatternField(null)
+                        ensureCloseParen(,, ()
+                        listener: handleRecordPattern((, 1)
+                    listener: beginAsOperatorType(as)
+                    computeTypeAfterIsOrAs(as)
+                    parseRecordType((, as, false)
+                      listener: beginRecordType(()
+                      parseRecordTypeField((, identifierIsOptional: true)
+                        listener: beginRecordTypeEntry()
+                        parseMetadataStar(()
+                          listener: beginMetadataStar(Object)
+                          listener: endMetadataStar(0)
+                        listener: handleIdentifier(Object, typeReference)
+                        listener: handleNoTypeArguments(,)
+                        listener: handleType(Object, null)
+                        listener: handleNoName(,)
+                        listener: endRecordTypeEntry()
+                      listener: endRecordType((, null, 1, false)
+                    listener: endAsOperatorType(as)
+                    listener: handleCastPattern(as)
+                    listener: endPattern())
+                  listener: handleSwitchCaseNoWhenClause())
+                  ensureColon())
+                  listener: endCaseExpression(case, null, :)
+                  peekPastLabels(})
+                  parseStatementsInSwitchCase(:, }, case, 0, 1, null, null)
+                    listener: beginSwitchCase(0, 1, case)
+                    listener: endSwitchCase(0, 1, null, null, 0, case, })
+                  notEofOrValue(}, })
+                  listener: endSwitchBlock(1, {, })
+                listener: endSwitchStatement(switch, })
+          notEofOrValue(}, })
+          listener: endBlockFunctionBody(1, {, })
+        listener: endTopLevelMethod(void, null, })
+  listener: endTopLevelDeclaration()
+  reportAllErrorTokens(void)
+  listener: endCompilationUnit(1, )

pkg/front_end/parser_testcases/patterns/recordPattern_nonNullable_beforeAs.dart.parser.expect

@@ -0,0 +1,13 @@
+void f(x) {
+switch (x) {
+case (_,) as (Object,):
+}
+}
+
+
+void[KeywordToken] f[StringToken]([BeginToken]x[StringToken])[SimpleToken] {[BeginToken]
+switch[KeywordToken] ([BeginToken]x[StringToken])[SimpleToken] {[BeginToken]
+case[KeywordToken] ([BeginToken]_[StringToken],[SimpleToken])[SimpleToken] as[KeywordToken] ([BeginToken]Object[StringToken],[SimpleToken])[SimpleToken]:[SimpleToken]
+}[SimpleToken]
+}[SimpleToken]
+[SimpleToken]

pkg/front_end/parser_testcases/patterns/recordPattern_nonNullable_beforeAs.dart.scanner.expect

@@ -0,0 +1,13 @@
+void f(x) {
+switch (x) {
+case (_,) as (Object,):
+}
+}
+
+
+void[KeywordToken] f[StringToken]([BeginToken]x[StringToken])[SimpleToken] {[BeginToken]
+switch[KeywordToken] ([BeginToken]x[StringToken])[SimpleToken] {[BeginToken]
+case[KeywordToken] ([BeginToken]_[StringToken],[SimpleToken])[SimpleToken] as[KeywordToken] ([BeginToken]Object[StringToken],[SimpleToken])[SimpleToken]:[SimpleToken]
+}[SimpleToken]
+}[SimpleToken]
+[SimpleToken]

pkg/front_end/parser_testcases/patterns/recordPattern_nonNullable_beforeWhen.dart

@@ -0,0 +1,5 @@
+void f(x) {
+  switch (x) {
+    case (_,) when true:
+  }
+}

pkg/front_end/parser_testcases/patterns/recordPattern_nonNullable_beforeWhen.dart.expect

@@ -0,0 +1,47 @@
+beginCompilationUnit(void)
+  beginMetadataStar(void)
+  endMetadataStar(0)
+  beginTopLevelMember(void)
+    beginTopLevelMethod(, null, null)
+      handleVoidKeyword(void)
+      handleIdentifier(f, topLevelFunctionDeclaration)
+      handleNoTypeVariables(()
+      beginFormalParameters((, MemberKind.TopLevelMethod)
+        beginMetadataStar(x)
+        endMetadataStar(0)
+        beginFormalParameter(x, MemberKind.TopLevelMethod, null, null, null)
+          handleNoType(()
+          handleIdentifier(x, formalParameterDeclaration)
+          handleFormalParameterWithoutValue())
+        endFormalParameter(null, null, null, x, null, null, FormalParameterKind.requiredPositional, MemberKind.TopLevelMethod)
+      endFormalParameters(1, (, ), MemberKind.TopLevelMethod)
+      handleAsyncModifier(null, null)
+      beginBlockFunctionBody({)
+        beginSwitchStatement(switch)
+          handleIdentifier(x, expression)
+          handleNoTypeArguments())
+          handleNoArguments())
+          handleSend(x, ))
+          handleParenthesizedCondition((, null, null)
+          beginSwitchBlock({)
+            beginCaseExpression(case)
+              beginPattern(case)
+                beginPattern(()
+                  handleNoType(_)
+                  handleWildcardPattern(null, _)
+                endPattern(_)
+                handlePatternField(null)
+                handleRecordPattern((, 1)
+              endPattern())
+              beginSwitchCaseWhenClause(when)
+                handleLiteralBool(true)
+              endSwitchCaseWhenClause(true)
+            endCaseExpression(case, when, :)
+            beginSwitchCase(0, 1, case)
+            endSwitchCase(0, 1, null, null, 0, case, })
+          endSwitchBlock(1, {, })
+        endSwitchStatement(switch, })
+      endBlockFunctionBody(1, {, })
+    endTopLevelMethod(void, null, })
+  endTopLevelDeclaration()
+endCompilationUnit(1, )