Avoid ICE when include! is used by stdin crate

[mystor]

This should hopefully also eliminate the ICE when using include_bytes!, include_str! and #[doc(include = "...")] with a stdio input.

I couldn't see a clear way to write a compile-fail test using compiletest with a stdio input, so I haven't written any tests for this change.

Fixes #63900

[rust-highfive]

r? @alexcrichton

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[Centril]

Please use the same formatting as the method below.

[mystor]

OK. Wasn't sure what style to use, so copied from this method: https://github.com/rust-lang/rust/blob/0b97ef8d5f78ea7144dbc2afb0ff3e055fb5056a/src/libsyntax_expand/base.rs#L1126-L1127

[Centril]

r? @petrochenkov

[rust-highfive]

The job mingw-check of your PR failed (pretty log, raw log). Through arcane magic we have determined that the following fragments from the build log may contain information about the problem.

Click to expand the log.

2019-10-19T17:28:19.4295857Z ##[command]git remote add origin https://github.com/rust-lang/rust
2019-10-19T17:28:19.4482915Z ##[command]git config gc.auto 0
2019-10-19T17:28:19.4558003Z ##[command]git config --get-all http.https://github.com/rust-lang/rust.extraheader
2019-10-19T17:28:19.4637829Z ##[command]git config --get-all http.proxy
2019-10-19T17:28:19.4779538Z ##[command]git -c http.extraheader="AUTHORIZATION: basic ***" fetch --force --tags --prune --progress --no-recurse-submodules --depth=2 origin +refs/heads/*:refs/remotes/origin/* +refs/pull/65603/merge:refs/remotes/pull/65603/merge
---
2019-10-19T17:36:01.5471795Z     Checking syntax_expand v0.0.0 (/checkout/src/libsyntax_expand)
2019-10-19T17:36:01.7972598Z error[E0425]: cannot find value `cx` in this scope
2019-10-19T17:36:01.7973921Z     --> src/libsyntax_expand/expand.rs:1421:42
2019-10-19T17:36:01.7974316Z      |
2019-10-19T17:36:01.7975061Z 1421 |                     let filename = match cx.resolve_path(file, sp) {
2019-10-19T17:36:01.7975670Z      |                                          ^^ help: you might have meant to use the available field: `self.cx`
2019-10-19T17:36:01.7984107Z error[E0425]: cannot find value `sp` in this scope
2019-10-19T17:36:01.7985247Z     --> src/libsyntax_expand/expand.rs:1421:64
2019-10-19T17:36:01.7985867Z      |
2019-10-19T17:36:01.7985867Z      |
2019-10-19T17:36:01.7986480Z 1421 |                     let filename = match cx.resolve_path(file, sp) {
2019-10-19T17:36:01.7990566Z 
2019-10-19T17:36:02.6762754Z error: aborting due to 2 previous errors
2019-10-19T17:36:02.6762859Z 
2019-10-19T17:36:02.6763200Z For more information about this error, try `rustc --explain E0425`.
---
2019-10-19T17:36:02.7110771Z   local time: Sat Oct 19 17:36:02 UTC 2019
2019-10-19T17:36:02.8608549Z   network time: Sat, 19 Oct 2019 17:36:02 GMT
2019-10-19T17:36:02.8608890Z == end clock drift check ==
2019-10-19T17:36:04.1394511Z 
2019-10-19T17:36:04.1499185Z ##[error]Bash exited with code '1'.
2019-10-19T17:36:04.1531087Z ##[section]Starting: Checkout
2019-10-19T17:36:04.1532702Z ==============================================================================
2019-10-19T17:36:04.1532750Z Task         : Get sources
2019-10-19T17:36:04.1532810Z Description  : Get sources from a repository. Supports Git, TfsVC, and SVN repositories.

I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact @TimNN. (Feature Requests)

[petrochenkov]

@bors r+

[bors]

📌 Commit 9be0bd8 has been approved by petrochenkov