`feature(new_range)` applies to macro expansions and breaks their assumptions

[kpreid]

#![feature(new_range)] changes the meaning of .. syntax for the entire build, regardless of where the tokens came from. Therefore, it can break macros defined by crates not using new_range. I think it should instead be activated based on the span of the .. token, similar to how edition-specific behaviors are often implemented.

I encountered this while trying to test feature(new_range) in code that uses arcstr::literal_substr!.

Repro

Substitute crate name in the doctest as needed.

//! ```
//! #![feature(new_range, new_range_api)]
//! // should print 5
//! dbg!(playground::example!("hello"));
//! ```

#[macro_export]
macro_rules! example {
    ($s:literal) => {
        $crate::takes_range(0..$s.len())
    };
}

pub fn takes_range(range: core::ops::Range<usize>) -> usize {
    range.end
}

I expected to see this happen: The use of a macro defined by another crate should successfully compile.

Instead, this happened:

error[E0308]: mismatched types
  --> src/lib.rs:6:6
   |
 8 | dbg!(scratchpad::example!("hello"));
   |      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |      |
   |      expected `std::ops::Range<usize>`, found `std::range::Range<usize>`
   |      arguments to this function are incorrect
   |
   = note: expected struct `std::ops::Range<usize>`
              found struct `std::range::Range<usize>`
note: function defined here
  --> src/lib.rs:14:8
   |
14 | pub fn takes_range(range: core::ops::Range<usize>) -> usize {
   |        ^^^^^^^^^^^
   = note: this error originates in the macro `scratchpad::example` (in Nightly builds, run with -Z macro-backtrace for more info)
help: call `Into::into` on this expression to convert `std::range::Range<usize>` into `std::ops::Range<usize>`
   |
 8 | dbg!(scratchpad::example!("hello").into());
   |                                   +++++++

Meta

rustc --version --verbose:

rustc 1.93.0-nightly (292be5c7c 2025-10-29)
binary: rustc
commit-hash: 292be5c7c05138d753bbd4b30db7a3f1a5c914f7
commit-date: 2025-10-29
host: aarch64-apple-darwin
release: 1.93.0-nightly
LLVM version: 21.1.3

@rustbot label +F-new_range