checker: fix generic infix expr type mismatch error (#18706)

vlib/v/checker/infix.v

@@ -743,6 +743,14 @@ fn (mut c Checker) infix_expr(mut node ast.InfixExpr) ast.Type {
 
 	// Dual sides check (compatibility check)
 	if node.left !is ast.ComptimeCall && node.right !is ast.ComptimeCall {
+		if left_type.has_flag(.generic) {
+			left_type = c.unwrap_generic(left_type)
+			left_sym = c.table.sym(left_type)
+		}
+		if right_type.has_flag(.generic) {
+			right_type = c.unwrap_generic(right_type)
+			right_sym = c.table.sym(right_type)
+		}
 		if !(c.symmetric_check(left_type, right_type) && c.symmetric_check(right_type, left_type))
 			&& !c.pref.translated && !c.file.is_translated && !node.left.is_auto_deref_var()
 			&& !node.right.is_auto_deref_var() {

vlib/v/checker/tests/generic_eq_wrong_type.err.out

@@ -0,0 +1,7 @@
+vlib/v/checker/tests/generic_eq_wrong_type.err.vv:9:13: error: infix expr: cannot use `string` (right expression) as `rune`
+    7 |         if ztest == `\n` {
+    8 |             println('${z}: \\n')
+    9 |         } else if ztest == '\r' {
+      |                   ~~~~~~~~~~~~~
+   10 |             println('${z}: \\r')
+   11 |         } else {

vlib/v/checker/tests/generic_eq_wrong_type.err.vv

@@ -0,0 +1,24 @@
+struct Scanner[T] {
+	contents []T
+}
+
+pub fn (s Scanner[T]) tokenize() {
+	for z, ztest in s.contents {
+		if ztest == `\n` {
+			println('${z}: \\n')
+		} else if ztest == '\r' {
+			println('${z}: \\r')
+		} else {
+			println('${z}: ${ztest}')
+		}
+	}
+}
+
+pub fn new_scanner[T](contents []T) Scanner[T] {
+	return Scanner[T]{contents}
+}
+
+fn main() {
+	s := new_scanner([`\n`, `b`])
+	s.tokenize()
+}