Rollup merge of #130883 - madsmtm:env-var-query, r=petrochenkov

Add environment variable query

Generally, `rustc` prefers command-line arguments, but in some cases, an environment variable really is the most sensible option. We should make sure that this works properly with the compiler's change-tracking mechanisms, such that changing the relevant environment variable causes a rebuild.

This PR is a first step forwards in doing that.

Part of the work needed to do https://github.com/rust-lang/rust/issues/118204, see https://github.com/rust-lang/rust/pull/129342 for some discussion.

r? ``@petrochenkov``

2 files changed, 36 insertions, 0 deletions

diff --git a/tests/incremental/env/env_macro.rs b/tests/incremental/env/env_macro.rs
new file mode 100644
index 00000000000..0c026328874
--- /dev/null
+++ b/tests/incremental/env/env_macro.rs
@@ -0,0 +1,18 @@
+// Check that changes to environment variables are propagated to `env!`.
+//
+// This test is intentionally written to not use any `#[cfg(rpass*)]`, to
+// _really_ test that we re-compile if the environment variable changes.
+
+//@ revisions: cfail1 rpass2 rpass3 cfail4
+//@ [cfail1]unset-rustc-env:EXAMPLE_ENV
+//@ [rpass2]rustc-env:EXAMPLE_ENV=one
+//@ [rpass2]exec-env:EXAMPLE_ENV=one
+//@ [rpass3]rustc-env:EXAMPLE_ENV=two
+//@ [rpass3]exec-env:EXAMPLE_ENV=two
+//@ [cfail4]unset-rustc-env:EXAMPLE_ENV
+
+fn main() {
+    assert_eq!(env!("EXAMPLE_ENV"), std::env::var("EXAMPLE_ENV").unwrap());
+    //[cfail1]~^ ERROR environment variable `EXAMPLE_ENV` not defined at compile time
+    //[cfail4]~^^ ERROR environment variable `EXAMPLE_ENV` not defined at compile time
+}
diff --git a/tests/incremental/env/option_env_macro.rs b/tests/incremental/env/option_env_macro.rs
new file mode 100644
index 00000000000..44c3bfd69e0
--- /dev/null
+++ b/tests/incremental/env/option_env_macro.rs
@@ -0,0 +1,18 @@
+// Check that changes to environment variables are propagated to `option_env!`.
+//
+// This test is intentionally written to not use any `#[cfg(rpass*)]`, to
+// _really_ test that we re-compile if the environment variable changes.
+
+//@ revisions: rpass1 rpass2 rpass3 rpass4
+//@ [rpass1]unset-rustc-env:EXAMPLE_ENV
+//@ [rpass1]unset-exec-env:EXAMPLE_ENV
+//@ [rpass2]rustc-env:EXAMPLE_ENV=one
+//@ [rpass2]exec-env:EXAMPLE_ENV=one
+//@ [rpass3]rustc-env:EXAMPLE_ENV=two
+//@ [rpass3]exec-env:EXAMPLE_ENV=two
+//@ [rpass4]unset-rustc-env:EXAMPLE_ENV
+//@ [rpass4]unset-exec-env:EXAMPLE_ENV
+
+fn main() {
+    assert_eq!(option_env!("EXAMPLE_ENV"), std::env::var("EXAMPLE_ENV").ok().as_deref());
+}