feat: Format strings for prints

[vezenovm]

Description

Enables printing multiple different types in the same statement and string as well as a new fmtstr type. A fmtstr can be specified in the same way as a normal string it just should be prepended with an f character:

    let fmt_str = f"i: {i}, j: {j}";
    std::println(fmt_str);

    let s = myStruct { y: x, x: y };
    std::println(s);

    std::println(f"i: {i}, s: {s}");

    std::println(x);
    std::println([x, y]);
    
    let foo = fooStruct { my_struct: s, foo: 15 };
    std::println(f"s: {s}, foo: {foo}");

Problem*

Resolves this comment: #1917 (comment)

Summary*

A new format string type was introduced in the frontend and all the relevant passes. Auser can invoke string interpolation by prepending a string literal with the f character. Comparisons between format strings is currently not enabled as they are only really used for printing. This can be easily changed though.

This code:

let string = "i: {i}, j: {j}";
std::println(string);

// A `fmtstr` lets you easily perform string interpolation.
let fmt_str: fmtstr<14, (Field, Field)> = f"i: {i}, j: {j}";
let fmt_str = string_identity(fmt_str);
std::println(fmt_str);

let fmt_str_no_type = f"i: {i}, j: {j}";
std::println(fmt_str_no_type);

let fmt_str_generic = string_with_generic(fmt_str_no_type);
std::println(fmt_str_generic);

fn string_identity(string: str<14>) -> str<14> {
    string
}

fn string_with_generic<T>(string: T) -> T {
    string
}

will output this:

"i: {i}, j: {j}"
i: "0x05", j: "0x0a"
i: "0x05", j: "0x0a"
i: "0x05", j: "0x0a"

The debug_logs test under nargo_cli/tests/test_data_ssa_refactor will give this output:

"i: {i}, j: {j}"
i: "0x05", j: "0x0a"
i: "0x05", j: "0x0a"
i: "0x05", j: "0x0a"
{"x":"0x0a","y":"0x05"}
randomstring"0x05""0x05"
i: "0x05", s: {"x":"0x0a","y":"0x05"}
"0x05"
["0x05","0x0a"]
s: {"x":"0x0a","y":"0x05"}, foo: {"foo":"0x0a","my_struct":{"x":"0x05","y":"0x0a"}}
x: 0, y: 1
s1: {"x":"0x0a","y":"0x05"}, s2: {"x":"0x1e","y":"0x0a"}
foo1: {"foo":"0x0f","my_struct":{"x":"0x0a","y":"0x05"}}, foo2: {"foo":"0x1e","my_struct":{"x":"0x0f","y":"0x0a"}}

Ideally the same string interpolation strategy can be used for a format function that returns a string slice once we can handle slices returned from unconstrained functions inside of ACIR.

Documentation

• This PR requires documentation updates when merged.

  • I will submit a noir-lang/docs PR.
  • I will request for and support Dev Rel's help in documenting this PR.

Additional Context

PR Checklist*

• I have tested the changes locally.
• I have formatted the changes with Prettier and/or cargo fmt on default settings.

[jfecher]

Still some final changes before we merge

[jfecher]

👍