syntax: simplify zsh logic on left parentheses

This does slightly alter two error messages,
but not in a way that feels wrong or worse.
If anything, we're making the logic simpler and more consistent.

Author: mvdan

syntax/parser.go

@@ -1339,7 +1339,7 @@ func (p *Parser) wordPart() WordPart {
 		}
 		return cs
 	case leftParen:
-		if p.lang.in(LangZsh) && p.r != ')' && (!p.spaced || p.quote == testExpr) {
+		if p.lang.in(LangZsh) && p.r != ')' {
 			// Zsh glob qualifier like *(N) or .(:a); the only case where
 			// ( immediately after a word is not a glob qualifier is ()
 			// for a function declaration, which the parser handles earlier.

syntax/parser_test.go

@@ -994,6 +994,7 @@ var errorCases = []errorCase{
 	errCase(
 		"for i in 1 2 (",
 		langErr("1:14: word list can only contain words"),
+		langErr("1:14: reached EOF without matching `(` with `)`", LangZsh),
 	),
 	errCase(
 		"for i in 1 2 3; do echo $i;",
@@ -1663,7 +1664,8 @@ var errorCases = []errorCase{
 	),
 	errCase(
 		"local (",
-		langErr("1:7: `local` must be followed by names or assignments", LangBash|LangZsh),
+		langErr("1:7: `local` must be followed by names or assignments", LangBash),
+		langErr("1:7: reached EOF without matching `(` with `)`", LangZsh),
 	),
 	errCase(
 		"declare 0=${o})",