fix: check infix expression is valid in program input (noir-lang#6450)

compiler/noirc_frontend/src/hir_def/types.rs

@@ -1212,7 +1212,6 @@ impl Type {
             | Type::Forall(_, _)
             | Type::Quoted(_)
             | Type::Slice(_)
-            | Type::InfixExpr(_, _, _)
             | Type::TraitAsType(..) => false,
 
             Type::CheckedCast { to, .. } => to.is_valid_for_program_input(),
@@ -1232,6 +1231,10 @@ impl Type {
                 .get_fields(generics)
                 .into_iter()
                 .all(|(_, field)| field.is_valid_for_program_input()),
+
+            Type::InfixExpr(lhs, _, rhs) => {
+                lhs.is_valid_for_program_input() && rhs.is_valid_for_program_input()
+            }
         }
     }
 

compiler/noirc_frontend/src/tests.rs

@@ -3771,3 +3771,41 @@ fn use_type_alias_to_generic_concrete_type_in_method_call() {
     "#;
     assert_no_errors(src);
 }
+
+#[test]
+fn allows_struct_with_generic_infix_type_as_main_input_1() {
+    let src = r#"
+        struct Foo<let N: u32> {
+            x: [u64; N * 2],
+        }
+
+        fn main(_x: Foo<18>) {}
+    "#;
+    assert_no_errors(src);
+}
+
+#[test]
+fn allows_struct_with_generic_infix_type_as_main_input_2() {
+    let src = r#"
+        struct Foo<let N: u32> {
+            x: [u64; N * 2],
+        }
+
+        fn main(_x: Foo<2 * 9>) {}
+    "#;
+    assert_no_errors(src);
+}
+
+#[test]
+fn allows_struct_with_generic_infix_type_as_main_input_3() {
+    let src = r#"
+        struct Foo<let N: u32> {
+            x: [u64; N * 2],
+        }
+
+        global N = 9;
+
+        fn main(_x: Foo<N * 2>) {}
+    "#;
+    assert_no_errors(src);
+}