fix: quote the original expansion in no-unquoted-expansions message

The message rebuilt every parameter as ${name}, dropping subscripts and
operators. It now interpolates the expansion's source text.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Author: nzakas

src/rules/no-unquoted-expansions.spec.ts

@@ -50,6 +50,7 @@ ruleTester.run("no-unquoted-expansions", rule as never, {
 			errors: [
 				{
 					messageId: "unquotedParameterExpansion",
+					data: { expansion: "$var" },
 					line: 1,
 					column: 6,
 					endColumn: 10,
@@ -61,6 +62,27 @@ ruleTester.run("no-unquoted-expansions", rule as never, {
 			output: 'echo "${var}"',
 			errors: [{ messageId: "unquotedParameterExpansion" }],
 		},
+		{
+			// The message quotes the expansion as written
+			code: "echo ${arr[@]}",
+			output: 'echo "${arr[@]}"',
+			errors: [
+				{
+					messageId: "unquotedParameterExpansion",
+					data: { expansion: "${arr[@]}" },
+				},
+			],
+		},
+		{
+			code: "echo ${var:-default}",
+			output: 'echo "${var:-default}"',
+			errors: [
+				{
+					messageId: "unquotedParameterExpansion",
+					data: { expansion: "${var:-default}" },
+				},
+			],
+		},
 		{
 			code: "echo $@",
 			output: 'echo "$@"',

src/rules/no-unquoted-expansions.ts

@@ -29,7 +29,7 @@ const rule: BashRuleDefinition<{
 		schema: [],
 		messages: {
 			unquotedParameterExpansion:
-				'Double quote "${{name}}" to prevent word splitting and globbing. (ShellCheck SC2086)',
+				'Double quote "{{expansion}}" to prevent word splitting and globbing. (ShellCheck SC2086)',
 			unquotedCommandSubstitution:
 				"Quote this command substitution to prevent word splitting. (ShellCheck SC2046)",
 		},
@@ -67,7 +67,7 @@ const rule: BashRuleDefinition<{
 							: "unquotedCommandSubstitution",
 					data:
 						part.type === "ParameterExpansion"
-							? { name: part.name }
+							? { expansion: sourceCode.getText(part) }
 							: {},
 					fix: isWholeWord
 						? fixer =>