fix a crash in rustdoc merge finalize without input file

[el-ev]

• Closes rustdoc crashes when running --merge=finalize without an input crate root #146646

SerializedSearchIndex::union calls Symbol::intern, requiring SESSION_GLOBALS to be set.

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[GuillaumeGomez]

Thanks! Can you add a regression test please?

[el-ev]

I tried but couldn't write a test. The test utility automatically passes the current file path to rustdoc, so there's always an input file and it won't crash. I would appreciate any help with this.

[GuillaumeGomez]

You can create a run-make tests like tests/run-make/rustdoc-map-file/rmake.rs.

[el-ev]

You can create a run-make tests like tests/run-make/rustdoc-map-file/rmake.rs.

Test added, thanks.

[GuillaumeGomez]

Please add a check to the output to ensure it doesn't crash.

Also, since you don't create a parts folder, I'm pretty sure it actually doesn't test the error:

error: --include-parts-dir expected parts/crate-info to be a file

So you need to create the folder and also the crate-info file into it too, and not empty too apparently otherwise we get:

error: could not write merged cross-crate info: "parts/crate-info": EOF while parsing a value at line 1 column 0

[el-ev]

Also, since you don't create a parts folder, I'm pretty sure it actually doesn't test the error

It doesn't test the error, it tests an ICE described in the linked issue.

So you need to create the folder and also the crate-info file into it too.

They should be created in the previous step by setting --parts-out-dir=parts.

[GuillaumeGomez]

Hum then it's surprising because I can't seem to reproduce it with latest nightly:

rustdoc 1.92.0-nightly (9f32ccf35 2025-09-21)

[el-ev]

That's strange. I can still reproduce it:

❯ rustdoc -vV
rustdoc 1.92.0-nightly (9f32ccf35 2025-09-21)
binary: rustdoc
commit-hash: 9f32ccf35fb877270bc44a86a126440f04d676d0
commit-date: 2025-09-21
host: aarch64-apple-darwin
release: 1.92.0-nightly
LLVM version: 21.1.1
❯ touch test.rs
❯ rustdoc test.rs -Zunstable-options --parts-out-dir=/tmp/parts_tmp --merge=none
❯ rustdoc -Zunstable-options --include-parts-dir=/tmp/parts_tmp --merge=finalize

thread 'main' (4343049) panicked at /rust/deps/scoped-tls-1.0.1/src/lib.rs:168:9:

[GuillaumeGomez]

Ah yes, got it. So two things missing: please check that the first command succeeded and created the expected files. And then check that the second command output doesn't contain the string error: internal compiler error:.

[el-ev]

Updated. .run() already implies a successful exit check.

[GuillaumeGomez]

Thanks!

@bors r+ rollup

[bors]

📌 Commit 42ebba2 has been approved by GuillaumeGomez

It is now in the queue for this repository.