Redefinitions

[zpnst]

🐞 Describe the bug

The absence of errors in redefining the variable and the strange bugs associated with it

💻 Environment

node version:

~/D/p/f/d/Test (master)> node --version
v18.19.0

npm version:

~/D/p/f/d/Test (master)> npm --version
10.9.0

The project was created using the following npm command(i.e. blueprint framework):

npm create ton@latest

FunC is compiled by the npx blueprint build command.

🔢 Code to reproduce bug

Redefinition

To begin with, this code compiles successfully and there are no errors in redefining the var1 variable.

#include "imports/stdlib.fc";

() recv_internal(int my_balance, int msg_value, cell in_msg_full, slice in_msg_body) impure {
    int var1 = 1;
    int var1 = 5;
    return ();
}

output

Using file: Test
Build script running, compiling Test

✅ Compiled successfully! Cell BOC result:

{
  "hash": "6ef6e4084167bca1464f9d2ddc8448bbd66df303c4014af50aeb5a109fdfb8cc",
  "hashBase64": "bvbkCEFnvKFGT50t3IRIu9Zt8wPEAUr1CutaEJ/fuMw=",
  "hex": "b5ee9c72410102010012000114ff00f4a413f4bcf2c80b010006d35f04109b75d3"
}

✅ Wrote compilation artifact to build/Test.compiled.json

Dictionary traversal

Next, let's look at the code where a completely legitimate dictionary bypass is added.
This code compiles with a very strange error for this situation.

#include "imports/stdlib.fc";

() recv_internal(int my_balance, int msg_value, cell in_msg_full, slice in_msg_body) impure {
    int var1 = 1;

    cell some_dict = new_dict();

    ;; bypassing the dictionary
    int pivot = -1;
    do {
        (pivot, slice info,  int success) = some_dict.udict_get_next?(256, pivot);
    } until( ~ success )

    ;; I want to write a different value to the var variable
    var1 = 5;

    return ();
}

output

Error: FunC compilation error: contracts/test.fc:15:10: error: cannot apply expression of type int to an expression of type int: cannot unify type int -> ??69 with int
      var1 = 5;

Dictionary traversal with redefinition

But if we just add a redefinition of the var1 variable, then suddenly there will be no compilation errors.

#include "imports/stdlib.fc";

() recv_internal(int my_balance, int msg_value, cell in_msg_full, slice in_msg_body) impure {
    int var1 = 1;

    cell some_dict = new_dict();

    ;; bypassing the dictionary
    int pivot = -1;
    do {
        (pivot, slice info,  int success) = some_dict.udict_get_next?(256, pivot);
    } until( ~ success )

    ;; I want to write a different value to the var variable
    int var1 = 5;

    return ();
}

Using file: Test
Build script running, compiling Test

✅ Compiled successfully! Cell BOC result:

{
  "hash": "0ce211bdd661f08273452996c83e2489c0f2d875d173cba08b0d7cc129eacd05",
  "hashBase64": "DOIRvdZh8IJzRSmWyD4kicDy2HXRc8ugiw18wSnqzQU=",
  "hex": "b5ee9c72410102010021000114ff00f4a413f4bcf2c80b010024d35f046d7f9a218307f47c6fa56c12b3e65b0058ae68"
}

✅ Wrote compilation artifact to build/Test.compiled.json