Implement --env compiler flag

Author: GuillaumeGomez

compiler/rustc_builtin_macros/src/env.rs

@@ -13,6 +13,16 @@ use thin_vec::thin_vec;
 
 usecrate::errors;
 
+fnlookup_env<'cx>(cx:&'cxExtCtxt<'_>,var:Symbol) -> Option<Symbol>{
+let var = var.as_str();
+ifletSome(value) = cx.sess.opts.logical_env.get(var){
+returnSome(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)
+}
+
 pubfnexpand_option_env<'cx>(
 cx:&'cxmutExtCtxt<'_>,
 sp:Span,
@@ -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 => {
@@ -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 => {

compiler/rustc_session/src/config.rs

@@ -8,7 +8,7 @@ use crate::search_paths::SearchPath;
 usecrate::utils::{CanonicalizedPath,NativeLib,NativeLibKind};
 usecrate::{lint,HashStableContext};
 usecrate::{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};
@@ -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(),
 }
 }
 }
@@ -1810,6 +1811,7 @@ 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
 }
@@ -2589,6 +2591,23 @@ fn parse_remap_path_prefix(
  mapping
 }
 
+fnparse_logical_env(
+handler:&mutEarlyErrorHandler,
+matches:&getopts::Matches,
+) -> FxIndexMap<String,String>{
+letmut vars = FxIndexMap::default();
+
+for arg in matches.opt_strs("env"){
+ifletSome((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)]
 pubfnbuild_session_options(
@@ -2827,6 +2846,8 @@ 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;
@@ -2907,6 +2928,7 @@ pub fn build_session_options(
  pretty,
  working_dir,
  color,
+ logical_env,
 }
 }
 
@@ -3181,6 +3203,7 @@ pub(crate) mod dep_tracking {
 };
 usecrate::lint;
 usecrate::utils::NativeLib;
+use rustc_data_structures::fx::FxIndexMap;
 use rustc_data_structures::stable_hasher::Hash64;
 use rustc_errors::LanguageIdentifier;
 use rustc_feature::UnstableFeatures;
@@ -3339,6 +3362,21 @@ pub(crate) mod dep_tracking {
 }
 }
 
+impl<T:DepTrackingHash,V:DepTrackingHash>DepTrackingHashforFxIndexMap<T,V>{
+fnhash(
+&self,
+hasher:&mutDefaultHasher,
+error_format:ErrorOutputType,
+for_crate_hash:bool,
+){
+Hash::hash(&self.len(), hasher);
+for(key, value)inself.iter(){
+DepTrackingHash::hash(key, hasher, error_format, for_crate_hash);
+DepTrackingHash::hash(value, hasher, error_format, for_crate_hash);
+}
+}
+}
+
 implDepTrackingHashforOutputTypes{
 fnhash(
 &self,

compiler/rustc_session/src/options.rs

@@ -3,6 +3,7 @@ use crate::config::*;
 usecrate::search_paths::SearchPath;
 usecrate::utils::NativeLib;
 usecrate::{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;
@@ -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],