Rollup merge of #113780 - dtolnay:printkindpath, r=b-naber

Support `--print KIND=PATH` command line syntax

As is already done for `--emit KIND=PATH` and `-L KIND=PATH`.

In the discussion of #110785, it was pointed out that `--print KIND=PATH` is nicer than trying to apply the single global `-o` path to `--print`'s output, because in general there can be multiple print requests within a single rustc invocation, and anyway `-o` would already be used for a different meaning in the case of `link-args` and `native-static-libs`.

I am interested in using `--print cfg=PATH` in Buck2. Currently Buck2 works around the lack of support for `--print KIND=PATH` by [indirecting through a Python wrapper script](https://github.com/facebook/buck2/blob/d43cf3a51a31f00be2c2248e78271b0fef0452b4/prelude/rust/tools/get_rustc_cfg.py) to redirect rustc's stdout into the location dictated by the build system.

From skimming Cargo's usages of `--print`, it definitely seems like it would benefit from `--print KIND=PATH` too. Currently it is working around the lack of this by inserting `--crate-name=___ --print=crate-name` so that it can look for a line containing `___` as a delimiter between the 2 other `--print` informations it actually cares about. This is commented as a "HACK" and "abuse". https://github.com/rust-lang/cargo/blob/31eda6f7c360d9911f853b3014e057db61238f3e/src/cargo/core/compiler/build_context/target_info.rs#L242 (FYI `@weihanglo` as you dealt with this recently in https://github.com/rust-lang/cargo/pull/11633.)

Mentioning reviewers active in #110785: `@fee1-dead` `@jyn514` `@bjorn3`

1 files changed, 0 insertions, 7 deletions

diff --git a/compiler/rustc_driver_impl/src/session_diagnostics.rs b/compiler/rustc_driver_impl/src/session_diagnostics.rs
index f7f06b7d0f2..5eb587c54d9 100644
--- a/compiler/rustc_driver_impl/src/session_diagnostics.rs
+++ b/compiler/rustc_driver_impl/src/session_diagnostics.rs
@@ -33,13 +33,6 @@ pub(crate) struct RLinkRustcVersionMismatch<'a> {
 pub(crate) struct RlinkNotAFile;
 
 #[derive(Diagnostic)]
-#[diag(driver_impl_unpretty_dump_fail)]
-pub(crate) struct UnprettyDumpFail {
-    pub path: String,
-    pub err: String,
-}
-
-#[derive(Diagnostic)]
 #[diag(driver_impl_ice)]
 pub(crate) struct Ice;