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Auto merge of #118368 - GuillaumeGomez:env-flag, r=Nilstrieb
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Implement `--env` compiler flag (without `tracked_env` support)

Part of #80792.
Implementation of rust-lang/compiler-team#653.
Not an implementation of rust-lang/rfcs#2794.

It adds the `--env` compiler flag option which allows to set environment values used by `env!` and `option_env!`.

Important to note: When trying to retrieve an environment variable value, it will first look into the ones defined with `--env`, and if there isn't one, then only it will look into the environment variables. So if you use `--env PATH=a`, then `env!("PATH")` will return `"a"` and not the actual `PATH` value.

As mentioned in the title, `tracked_env` support is not added here. I'll do it in a follow-up PR.

r? rust-lang/compiler
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bors committed Dec 10, 2023
2 parents ec41761 + dc2f77a commit d86d65b
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Showing 9 changed files with 107 additions and 3 deletions.
14 changes: 12 additions & 2 deletions compiler/rustc_builtin_macros/src/env.rs
Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,16 @@ use thin_vec::thin_vec;

use crate::errors;

fn lookup_env<'cx>(cx: &'cx ExtCtxt<'_>, var: Symbol) -> Option<Symbol> {
let var = var.as_str();
if let Some(value) = cx.sess.opts.logical_env.get(var) {
return Some(Symbol::intern(value));
}
// If the environment variable was not defined with the `--env` option, we try to retrieve it
// from rustc's environment.
env::var(var).ok().as_deref().map(Symbol::intern)
}

pub fn expand_option_env<'cx>(
cx: &'cx mut ExtCtxt<'_>,
sp: Span,
Expand All @@ -23,7 +33,7 @@ pub fn expand_option_env<'cx>(
};

let sp = cx.with_def_site_ctxt(sp);
let value = env::var(var.as_str()).ok().as_deref().map(Symbol::intern);
let value = lookup_env(cx, var);
cx.sess.parse_sess.env_depinfo.borrow_mut().insert((var, value));
let e = match value {
None => {
Expand Down Expand Up @@ -77,7 +87,7 @@ pub fn expand_env<'cx>(
};

let span = cx.with_def_site_ctxt(sp);
let value = env::var(var.as_str()).ok().as_deref().map(Symbol::intern);
let value = lookup_env(cx, var);
cx.sess.parse_sess.env_depinfo.borrow_mut().insert((var, value));
let e = match value {
None => {
Expand Down
40 changes: 39 additions & 1 deletion compiler/rustc_session/src/config.rs
Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,7 @@ use crate::search_paths::SearchPath;
use crate::utils::{CanonicalizedPath, NativeLib, NativeLibKind};
use crate::{lint, HashStableContext};
use crate::{EarlyErrorHandler, Session};
use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexSet};
use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap, FxIndexSet};
use rustc_data_structures::stable_hasher::{StableOrd, ToStableHashKey};
use rustc_errors::emitter::HumanReadableErrorType;
use rustc_errors::{ColorConfig, DiagnosticArgValue, HandlerFlags, IntoDiagnosticArg};
Expand Down Expand Up @@ -1114,6 +1114,7 @@ impl Default for Options {
pretty: None,
working_dir: RealFileName::LocalPath(std::env::current_dir().unwrap()),
color: ColorConfig::Auto,
logical_env: FxIndexMap::default(),
}
}
}
Expand Down Expand Up @@ -1813,6 +1814,7 @@ pub fn rustc_optgroups() -> Vec<RustcOptGroup> {
"Remap source names in all output (compiler messages and output files)",
"FROM=TO",
),
opt::multi("", "env", "Inject an environment variable", "VAR=VALUE"),
]);
opts
}
Expand Down Expand Up @@ -2592,6 +2594,23 @@ fn parse_remap_path_prefix(
mapping
}

fn parse_logical_env(
handler: &mut EarlyErrorHandler,
matches: &getopts::Matches,
) -> FxIndexMap<String, String> {
let mut vars = FxIndexMap::default();

for arg in matches.opt_strs("env") {
if let Some((name, val)) = arg.split_once('=') {
vars.insert(name.to_string(), val.to_string());
} else {
handler.early_error(format!("`--env`: specify value for variable `{arg}`"));
}
}

vars
}

// JUSTIFICATION: before wrapper fn is available
#[allow(rustc::bad_opt_access)]
pub fn build_session_options(
Expand Down Expand Up @@ -2830,6 +2849,8 @@ pub fn build_session_options(
handler.early_error("can't dump dependency graph without `-Z query-dep-graph`");
}

let logical_env = parse_logical_env(handler, matches);

// Try to find a directory containing the Rust `src`, for more details see
// the doc comment on the `real_rust_source_base_dir` field.
let tmp_buf;
Expand Down Expand Up @@ -2910,6 +2931,7 @@ pub fn build_session_options(
pretty,
working_dir,
color,
logical_env,
}
}

Expand Down Expand Up @@ -3184,6 +3206,7 @@ pub(crate) mod dep_tracking {
};
use crate::lint;
use crate::utils::NativeLib;
use rustc_data_structures::fx::FxIndexMap;
use rustc_data_structures::stable_hasher::Hash64;
use rustc_errors::LanguageIdentifier;
use rustc_feature::UnstableFeatures;
Expand Down Expand Up @@ -3342,6 +3365,21 @@ pub(crate) mod dep_tracking {
}
}

impl<T: DepTrackingHash, V: DepTrackingHash> DepTrackingHash for FxIndexMap<T, V> {
fn hash(
&self,
hasher: &mut DefaultHasher,
error_format: ErrorOutputType,
for_crate_hash: bool,
) {
Hash::hash(&self.len(), hasher);
for (key, value) in self.iter() {
DepTrackingHash::hash(key, hasher, error_format, for_crate_hash);
DepTrackingHash::hash(value, hasher, error_format, for_crate_hash);
}
}
}

impl DepTrackingHash for OutputTypes {
fn hash(
&self,
Expand Down
4 changes: 4 additions & 0 deletions compiler/rustc_session/src/options.rs
Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@ use crate::config::*;
use crate::search_paths::SearchPath;
use crate::utils::NativeLib;
use crate::{lint, EarlyErrorHandler};
use rustc_data_structures::fx::FxIndexMap;
use rustc_data_structures::profiling::TimePassesFormat;
use rustc_data_structures::stable_hasher::Hash64;
use rustc_errors::ColorConfig;
Expand Down Expand Up @@ -150,6 +151,9 @@ top_level_options!(

target_triple: TargetTriple [TRACKED],

/// Effective logical environment used by `env!`/`option_env!` macros
logical_env: FxIndexMap<String, String> [TRACKED],

test: bool [TRACKED],
error_format: ErrorOutputType [UNTRACKED],
diagnostic_width: Option<usize> [UNTRACKED],
Expand Down
26 changes: 26 additions & 0 deletions src/doc/unstable-book/src/compiler-flags/env.md
Original file line number Diff line number Diff line change
@@ -0,0 +1,26 @@
# `env`

The tracking issue for this feature is: [#118372](https://github.com/rust-lang/rust/issues/118372).

------------------------

This option flag allows to specify environment variables value at compile time to be
used by `env!` and `option_env!` macros.

When retrieving an environment variable value, the one specified by `--env` will take
precedence. For example, if you want have `PATH=a` in your environment and pass:

```bash
rustc --env PATH=env
```

Then you will have:

```rust,no_run
assert_eq!(env!("PATH"), "env");
```

Please note that on Windows, environment variables are case insensitive but case
preserving whereas `rustc`'s environment variables are case sensitive. For example,
having `Path` in your environment (case insensitive) is different than using
`rustc --env Path=...` (case sensitive).
9 changes: 9 additions & 0 deletions tests/ui/extenv/extenv-env-overload.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,9 @@
// run-pass
// rustc-env:MY_VAR=tadam
// compile-flags: --env MY_VAR=123abc -Zunstable-options

// This test ensures that variables provided with `--env` take precedence over
// variables from environment.
fn main() {
assert_eq!(env!("MY_VAR"), "123abc");
}
5 changes: 5 additions & 0 deletions tests/ui/extenv/extenv-env.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,5 @@
// compile-flags: --env FOO=123abc -Zunstable-options
// run-pass
fn main() {
assert_eq!(env!("FOO"), "123abc");
}
7 changes: 7 additions & 0 deletions tests/ui/extenv/extenv-not-env.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,7 @@
// run-pass
// rustc-env:MY_ENV=/
// Ensures that variables not defined through `--env` are still available.

fn main() {
assert!(!env!("MY_ENV").is_empty());
}
3 changes: 3 additions & 0 deletions tests/ui/feature-gates/env-flag.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,3 @@
// compile-flags: --env A=B

fn main() {}
2 changes: 2 additions & 0 deletions tests/ui/feature-gates/env-flag.stderr
Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
error: the `-Z unstable-options` flag must also be passed to enable the flag `env`

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