fix: skip optional -- after printf -v in format rule

Co-authored-by: nzakas <38546+nzakas@users.noreply.github.com>

Author: Copilot

docs/rules/no-variables-in-printf-format.md

@@ -8,7 +8,7 @@ The first argument to `printf` is a format string: `%` starts a conversion and `
 
 ## Rule Details
 
-This rule warns when the format argument of `printf` contains a parameter expansion or command substitution, whether or not it's quoted. The format is the first argument, or the argument after `-v name`, `-vname`, or `--`.
+This rule warns when the format argument of `printf` contains a parameter expansion or command substitution, whether or not it's quoted. The format is the first argument after an optional `-v name` or `-vname` and an optional `--`.
 
 Variables in the arguments after the format are fine. Arithmetic expansions such as `$((...))` in the format are not checked.
 

src/rules/no-variables-in-printf-format.spec.ts

@@ -21,6 +21,9 @@ ruleTester.run("no-variables-in-printf-format", rule as never, {
 		'printf "%s\\n" "$var"',
 		'printf \'%s: %d\\n\' "$name" "$count"',
 		'printf -v result "%s" "$var"',
+		'printf -v result -- "%s" "$var"',
+		'printf -vresult -- "%s" "$var"',
+		'printf -- "%s" "$var"',
 		'printf "static text\\n"',
 		// Not printf
 		'echo "$var"',
@@ -49,6 +52,18 @@ ruleTester.run("no-variables-in-printf-format", rule as never, {
 			code: 'printf -v out "$fmt" x',
 			errors: [{ messageId: "variableInFormat" }],
 		},
+		{
+			code: 'printf -v out -- "$fmt" x',
+			errors: [{ messageId: "variableInFormat" }],
+		},
+		{
+			code: 'printf -vout -- "$fmt" x',
+			errors: [{ messageId: "variableInFormat" }],
+		},
+		{
+			code: 'printf -- "$fmt" x',
+			errors: [{ messageId: "variableInFormat" }],
+		},
 		{
 			code: 'printf "count: $(wc -l < file)\\n"',
 			errors: [{ messageId: "variableInFormat" }],

src/rules/no-variables-in-printf-format.ts

@@ -40,8 +40,11 @@ const rule: BashRuleDefinition<{ MessageIds: "variableInFormat" }> = {
 				} else if (first !== null && first.startsWith("-v")) {
 					// `printf -vvar format ...`
 					formatIndex = 1;
-				} else if (first === "--") {
-					formatIndex = 1;
+				}
+
+				const possibleFormat = node.arguments[formatIndex];
+				if (possibleFormat && getStaticText(possibleFormat) === "--") {
+					formatIndex++;
 				}
 
 				const format = node.arguments[formatIndex];