`concat!` does not respect integer literals' types

concat!(1234u8) constructs the string literal without checking whether the value is out-of-bounds for the given integer type.

Seems related to #115423.

I tried this code:

fn main() {
    let s = concat!(999999999u8);
    println!("{s}");
}

I expected to see this happen: error: literal out of range for u8

Instead, this happened: Prints 999999999, no error

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rustc --version --verbose:

rustc 1.97.1 (8bab26f4f 2026-07-14)
binary: rustc
commit-hash: 8bab26f4f68e0e26f0bb7960be334d5b520ea452
commit-date: 2026-07-14
host: aarch64-apple-darwin
release: 1.97.1
LLVM version: 22.1.6

(also occurs on Rust playground)

Notably, stringify! also doesn't error out; however, this seems expected, since stringify! deals with tokens rather than actual values (unlike concat!).

Start by reproducing the concat!(999999999u8) example with the Rust compiler and inspect how concat! handles typed integer literals. Compare the behavior with the related issue #115423. Done means out-of-range integer literals passed to concat! produce the expected u8 range error rather than being emitted as a string.