Share code for parsing local functions.

pkg/front_end/lib/src/fasta/parser/parser.dart

Index: pkg/front_end/lib/src/fasta/parser/parser.dart
diff --git a/pkg/front_end/lib/src/fasta/parser/parser.dart b/pkg/front_end/lib/src/fasta/parser/parser.dart
index c2c49517661540064ba3c8df8283d1b95682ef98..695981294cb8538d0d51dcc91d8163122f69bebc 100644
--- a/pkg/front_end/lib/src/fasta/parser/parser.dart
+++ b/pkg/front_end/lib/src/fasta/parser/parser.dart
@@ -1203,11 +1203,7 @@ class Parser {
               } else {
                 commitType();
               }
-              listener.beginFunctionName(token);
-              token = parseIdentifier(
-                  token, IdentifierContext.localFunctionDeclaration);
-              listener.endFunctionName(begin, token);
-              return parseLocalFunctionDeclarationFromFormals(formals);
+              return parseLocalFunctionDeclarationRest(begin, token, formals);
             }
           } else if (identical(afterIdKind, LT_TOKEN)) {
             // We are looking at `type identifier '<'`.
@@ -1224,11 +1220,7 @@ class Parser {
                 } else {
                   commitType();
                 }
-                listener.beginFunctionName(token);
-                token = parseIdentifier(
-                    token, IdentifierContext.localFunctionDeclaration);
-                listener.endFunctionName(begin, token);
-                return parseLocalFunctionDeclarationFromFormals(formals);
+                return parseLocalFunctionDeclarationRest(begin, token, formals);
               }
             }
           }
@@ -1249,11 +1241,7 @@ class Parser {
               listener.beginLocalFunctionDeclaration(token);
               listener.handleModifiers(0);
               listener.handleNoType(token);
-              listener.beginFunctionName(token);
-              token = parseIdentifier(
-                  token, IdentifierContext.localFunctionDeclaration);
-              listener.endFunctionName(begin, token);
-              return parseLocalFunctionDeclarationFromFormals(formals);
+              return parseLocalFunctionDeclarationRest(begin, token, formals);
             }
           } else if (optional('<', token.next)) {
             Token afterTypeVariables = closeBraceTokenFor(token.next)?.next;
@@ -1267,12 +1255,8 @@ class Parser {
                 listener.beginLocalFunctionDeclaration(token);
                 listener.handleModifiers(0);
                 listener.handleNoType(token);
-                listener.beginFunctionName(token);
-                token = parseIdentifier(
-                    token, IdentifierContext.localFunctionDeclaration);
-                listener.endFunctionName(begin, token);
-                return parseLocalFunctionDeclarationFromFormals(
-                    afterTypeVariables);
+                return parseLocalFunctionDeclarationRest(
+                    begin, token, afterTypeVariables);
               }
             }
             // Fall through to expression statement.
@@ -2371,17 +2355,14 @@ class Parser {
     Token beginToken = token;
     listener.beginFunctionExpression(token);
     token = parseFormalParameters(token, MemberKind.Local);
-    AsyncModifier savedAsyncModifier = asyncState;
-    token = parseAsyncModifier(token);
-    bool isBlock = optional('{', token);
-    token = parseFunctionBody(token, true, false);
-    asyncState = savedAsyncModifier;
+    token = parseAsyncOptBody(token, true, false);
     listener.endFunctionExpression(beginToken, token);
-    return isBlock ? token.next : token;
+    return token;
   }
 
-  /// Parses the rest of a local function declaration starting from formal
-  /// parameters.
+  /// Parses the rest of a local function declaration starting from its [name]
+  /// but then skips any type parameters and continue parsing from [formals]
+  /// (the formal parameters).
   ///
   /// Precondition: the parser has previously generated these events:
   ///
@@ -2389,17 +2370,17 @@ class Parser {
   /// - beginLocalFunctionDeclaration.
   /// - Modifiers.
   /// - Return type.
-  /// - Function name.
-  Token parseLocalFunctionDeclarationFromFormals(Token token) {
-    token = parseFormalParametersOpt(token, MemberKind.Local);
+  Token parseLocalFunctionDeclarationRest(
+      Token begin, Token name, Token formals) {
+    Token token = name;
+    listener.beginFunctionName(token);
+    token = parseIdentifier(token, IdentifierContext.localFunctionDeclaration);
+    listener.endFunctionName(begin, token);
+    token = parseFormalParametersOpt(formals, MemberKind.Local);
     token = parseInitializersOpt(token);
-    AsyncModifier savedAsyncModifier = asyncState;
-    token = parseAsyncModifier(token);
-    token = parseFunctionBody(token, false, true);
-    asyncState = savedAsyncModifier;
-    token = token.next;
+    token = parseAsyncOptBody(token, false, false);
     listener.endLocalFunctionDeclaration(token);
-    return token;
+    return token.next;
   }
 
   /// Parses a named function expression which isn't legal syntax in Dart.
@@ -2422,13 +2403,24 @@ class Parser {
     token = parseTypeVariablesOpt(token);
     token = parseFormalParameters(token, MemberKind.Local);
     listener.handleNoInitializers();
+    token = parseAsyncOptBody(token, true, false);
+    listener.endNamedFunctionExpression(token);
+    return token;
+  }
+
+  /// Parses a function body optionally preceded by an async modifier (see
+  /// [parseAsyncModifier]).  This method is used in both expression context
+  /// (when [isExpression] is true) and statement context. In statement context
+  /// (when [isExpression] is false), and if the function body is on the form
+  /// `=> expression`, a trailing semicolon is required.
+  ///
+  /// It's an error if there's no function body unless [allowAbstract] is true.
+  Token parseAsyncOptBody(Token token, bool isExpression, bool allowAbstract) {
     AsyncModifier savedAsyncModifier = asyncState;
     token = parseAsyncModifier(token);
-    bool isBlock = optional('{', token);
-    token = parseFunctionBody(token, true, false);
+    token = parseFunctionBody(token, isExpression, allowAbstract);
     asyncState = savedAsyncModifier;
-    listener.endNamedFunctionExpression(token);
-    return isBlock ? token.next : token;
+    return token;
   }
 
   Token parseConstructorReference(Token token) {
@@ -2489,6 +2481,12 @@ class Parser {
     return token;
   }
 
+  /// Parses a function body.  This method is used in both expression context
+  /// (when [isExpression] is true) and statement context. In statement context
+  /// (when [isExpression] is false), and if the function body is on the form
+  /// `=> expression`, a trailing semicolon is required.
+  ///
+  /// It's an error if there's no function body unless [allowAbstract] is true.
   Token parseFunctionBody(Token token, bool isExpression, bool allowAbstract) {
     if (optional(';', token)) {
       if (!allowAbstract) {
@@ -2537,7 +2535,7 @@ class Parser {
     }
     listener.endBlockFunctionBody(statementCount, begin, token);
     expect('}', token);
-    return token;
+    return isExpression ? token.next : token;
   }
 
   Token skipAsyncModifier(Token token) {