Fix closure HIR span context mismatch

[cijiugechu]

Ensure span has the closure expression's SyntaxContext.

Closes #155724

[rustbot]

r? @chenyukang

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[chenyukang]

Thanks!
@bors r=chenyukang

[rust-bors]

📌 Commit 06cb86d has been approved by chenyukang

It is now in the queue for this repository.

[rust-log-analyzer]

The job x86_64-gnu-llvm-21-1 failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

test expr_store::scope::tests::while_let_adds_binding ... ok
test expr_store::tests::body::array_element_cfg ... ok
test expr_store::tests::body::block::inner_item_smoke ... ok
test expr_store::tests::body::async_fn_weird_param_patterns ... ok
error: test failed, to rerun pass `-p hir-def --lib`

Caused by:
  process didn't exit successfully: `/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-tools/x86_64-unknown-linux-gnu/release/deps/hir_def-c439368f2b64a049 '--skip=tests::smoke_test_real_sysroot_cargo' --skip=check_code_formatting -Z unstable-options --format json` (signal: 11, SIGSEGV: invalid memory reference)
Bootstrap failed while executing `--stage 2 test --skip tests --skip coverage-map --skip coverage-run --skip library --skip tidyselftest`
Build completed unsuccessfully in 1:09:51
  local time: Sun May  3 03:24:18 UTC 2026
  network time: Sun, 03 May 2026 03:24:18 GMT
##[error]Process completed with exit code 1.

[rust-bors]

💔 Test for 3022524 failed: CI. Failed job:

• auto - x86_64-gnu-llvm-21-1 (web logs, enhanced plaintext logs)