fix case sensitivity on check for format() calls

Author: rhysd

expr_insecure_test.go

@@ -195,14 +195,14 @@ func TestExprInsecureDetectUntrustedValue(t *testing.T) {
 			},
 		},
 		testCase{
-			"format('{} {}', github.event.pages.*.page_name, github.event.issue.title)",
+			"format('{0} {1}', github.event.pages.*.page_name, github.event.issue.title)",
 			[]string{
 				"github.event.pages.*.page_name",
 				"github.event.issue.title",
 			},
 		},
 		testCase{
-			"format('{} {}', github.event.*.body, github.event.*.*)",
+			"format('{0} {1}', github.event.*.body, github.event.*.*)",
 			[]string{
 				"github.event.",
 				"github.event.",

expr_sema.go

@@ -786,11 +786,11 @@ func checkFuncSignature(n *FuncCallNode, sig *FuncSignature, args []ExprType) *E
 	return nil
 }
 
-func (sema *ExprSemanticsChecker) checkBuiltinFunctionCall(n *FuncCallNode, sig *FuncSignature) {
+func (sema *ExprSemanticsChecker) checkBuiltinFunctionCall(n *FuncCallNode, _ *FuncSignature) {
 	sema.checkSpecialFunctionAvailability(n)
 
 	// Special checks for specific built-in functions
-	switch n.Callee {
+	switch strings.ToLower(n.Callee) {
 	case "format":
 		lit, ok := n.Args[0].(*StringNode)
 		if !ok {

expr_sema_test.go

@@ -495,7 +495,7 @@ func TestExprSemanticsCheckOK(t *testing.T) {
 			expected: StringType{},
 		},
 		{
-			what:     "format() function arguments varlidation",
+			what:     "format() function arguments validation",
 			input:    "format('{0}{0}{0} {1}{2}{1} {1}{2}{1}{2} {0} {1}{1}{1} {2}{2}{2} {0}{0}{0}{0} {0}', 1, 'foo', true)",
 			expected: StringType{},
 		},
@@ -1016,6 +1016,13 @@ func TestExprSemanticsCheckError(t *testing.T) {
 				"takes at least 2 parameters but 1 arguments are given",
 			},
 		},
+		{
+			what:  "function name of format() call check is case insensitive",
+			input: "Format('{0}', 1, 2)",
+			expected: []string{
+				`format string "{0}" does not contain placeholder {1}`,
+			},
+		},
 		{
 			what:  "undefined matrix value",
 			input: "matrix.bar",