Assign proper span to range expression

[marcusklaas]

Right trims the span for certain range expressions.

Closes #27162.

[rust-highfive]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @alexcrichton (or someone else) soon.

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[alexcrichton]

@bors: r+ b36d107

Thanks!

[bors]

⌛ Testing commit b36d107 with merge eb96fb6...

[bors]

💔 Test failed - auto-linux-32-opt

[alexcrichton]

@bors: retry

cc @gankro, that failure seems... worrying

failures:

---- btree::map::test_iter stdout ----
    thread 'btree::map::test_iter' panicked at 'assertion failed: `(left == right)` (left: `(9222, 9222)`, right: `(9216, 9216)`)', ../src/libcollectionstest/btree/map.rs:88



failures:
    btree::map::test_iter

test result: FAILED. 710 passed; 1 failed; 0 ignored; 0 measured

[bors]

⌛ Testing commit b36d107 with merge 2e5b165...

[alexcrichton]

I think I confused homu by accident, but all the tests passes so merging manually