Method parseArrowFunctionExpressionBody

internal/parser/parser.go:4468–4495

(isAsync bool, allowReturnTypeInArrowFunction bool)

}

func (p *Parser) parseArrowFunctionExpressionBody(isAsync bool, allowReturnTypeInArrowFunction bool) *ast.Node {
	if p.token == ast.KindOpenBraceToken {
		return p.parseFunctionBlock(core.IfElse(isAsync, ParseFlagsAwait, ParseFlagsNone), nil /*diagnosticMessage*/)
	}
	if p.token != ast.KindSemicolonToken && p.token != ast.KindFunctionKeyword && p.token != ast.KindClassKeyword && p.isStartOfStatement() && !p.isStartOfExpressionStatement() {
		// Check if we got a plain statement (i.e. no expression-statements, no function/class expressions/declarations)
		//
		// Here we try to recover from a potential error situation in the case where the
		// user meant to supply a block. For example, if the user wrote:
		//
		//  a =>
		//      let v = 0;
		//  }
		//
		// they may be missing an open brace.  Check to see if that's the case so we can
		// try to recover better.  If we don't do this, then the next close curly we see may end
		// up preemptively closing the containing construct.
		//
		// Note: even when 'IgnoreMissingOpenBrace' is passed, parseBody will still error.
		return p.parseFunctionBlock(ParseFlagsIgnoreMissingOpenBrace|core.IfElse(isAsync, ParseFlagsAwait, ParseFlagsNone), nil /*diagnosticMessage*/)
	}
	saveContextFlags := p.contextFlags
	p.setContextFlags(ast.NodeFlagsAwaitContext, isAsync)
	p.setContextFlags(ast.NodeFlagsYieldContext, false)
	node := p.parseAssignmentExpressionOrHigherWorker(allowReturnTypeInArrowFunction)
	p.contextFlags = saveContextFlags
	return node
}

func (p *Parser) isStartOfExpressionStatement() bool {
	// As per the grammar, none of '{' or 'function' or 'class' can start an expression statement.