fix: properly propagate constant value to assigned var in mast phase

examples/fixture/asm/kimchi/generic_nested_func.asm

@@ -1,4 +1,5 @@
 @ noname.0.7.0
+@ public inputs: 4
 
 DoubleGeneric<1>
 DoubleGeneric<1>

examples/fixture/asm/kimchi/generic_nested_method.asm

@@ -1,4 +1,5 @@
 @ noname.0.7.0
+@ public inputs: 4
 
 DoubleGeneric<1>
 DoubleGeneric<1>

examples/fixture/asm/r1cs/generic_nested_func.asm

@@ -1,4 +1,5 @@
 @ noname.0.7.0
+@ public inputs: 4
 
 v_4 == (v_1) * (1)
 v_4 == (v_2) * (1)

examples/fixture/asm/r1cs/generic_nested_method.asm

@@ -1,4 +1,5 @@
 @ noname.0.7.0
+@ public inputs: 4
 
 v_4 == (v_1) * (1)
 v_4 == (v_2) * (1)

examples/generic_for_loop.no

@@ -11,6 +11,16 @@ fn join(const LEN: Field, arr1: [Field; LLEN], arr2: [Field; RLEN]) -> [Field; L
     return arr;
 }
 
+fn accumulate_mut(const INIT: Field) -> Field {
+    // it shouldn't fold these variables, even they hold constant values
+    // it should only fold the generic vars
+    let mut zz = INIT;
+    for ii in 0..3 {
+        zz = zz + zz;
+    }
+    return zz;
+}
+
 fn main(pub xx: Field) {
     let arr1 = [xx + 1, xx + 2];
     let arr2 = [xx + 3, xx + 4];
@@ -21,4 +31,8 @@ fn main(pub xx: Field) {
     assert_eq(arr[1], arr1[1]);
     assert_eq(arr[2], arr2[0]);
     assert_eq(arr[3], arr2[1]);
+
+    let init_val = 1;
+    let res = accumulate_mut(init_val);
+    assert_eq(res, 8);
 }

src/mast/mod.rs

@@ -892,7 +892,7 @@ pub fn monomorphize_stmt<B: Backend>(
         StmtKind::Assign { mutable, lhs, rhs } => {
             let rhs_mono = monomorphize_expr(ctx, rhs, mono_fn_env)?;
             let typ = rhs_mono.typ.as_ref().expect("expected a type");
-            let type_info = MTypeInfo::new(typ, lhs.span, None);
+            let type_info = MTypeInfo::new(typ, lhs.span, rhs_mono.constant);
 
             // store the type of lhs in the env
             mono_fn_env.store_type(&lhs.value, &type_info)?;