fix: envs in config can trigger rebuild by custom build script with rerun-if-env-changed.

Author: linyihai

src/cargo/core/compiler/fingerprint/mod.rs

@@ -376,6 +376,7 @@ use std::time::SystemTime;
 use anyhow::{bail, format_err, Context as _};
 use cargo_util::{paths, ProcessBuilder, Sha256};
 use filetime::FileTime;
+use lazycell::LazyCell;
 use serde::de;
 use serde::ser;
 use serde::{Deserialize, Serialize};
@@ -792,14 +793,36 @@ pub enum StaleItem {
 impl LocalFingerprint {
     /// Read the environment variable of the given env `key`, and creates a new
     /// [`LocalFingerprint::RerunIfEnvChanged`] for it.
-    ///
-    // TODO: This is allowed at this moment. Should figure out if it makes
-    // sense if permitting to read env from the config system.
     #[allow(clippy::disallowed_methods)]
-    fn from_env<K: AsRef<str>>(key: K) -> LocalFingerprint {
+    fn from_env<K: AsRef<str>>(
+        key: K,
+        env_config: &Arc<HashMap<String, OsString>>,
+        env_config_insensitive: &Arc<LazyCell<HashMap<String, OsString>>>,
+    ) -> LocalFingerprint {
         let key = key.as_ref();
         let var = key.to_owned();
-        let val = env::var(key).ok();
+        let val = if let Some(val) = env::var(key).ok() {
+            Some(val)
+        } else {
+            match env_config.get(key) {
+                Some(value) => value.to_str().map(|s| s.to_string()),
+                None => {
+                    if cfg!(windows) {
+                        env_config_insensitive
+                            .borrow_with(|| {
+                                env_config
+                                    .iter()
+                                    .map(|(k, v)| (k.to_uppercase().clone(), v.clone()))
+                                    .collect::<HashMap<String, OsString>>()
+                            })
+                            .get(&key.to_uppercase())
+                            .and_then(|s| s.to_str().map(|s| s.to_string()))
+                    } else {
+                        None
+                    }
+                }
+            }
+        };
         LocalFingerprint::RerunIfEnvChanged { var, val }
     }
 
@@ -1697,6 +1720,7 @@ fn build_script_local_fingerprints(
     // obvious.
     let pkg_root = unit.pkg.root().to_path_buf();
     let target_dir = target_root(build_runner);
+    let env_config = Arc::clone(build_runner.bcx.gctx.env_config().unwrap());
     let calculate =
         move |deps: &BuildDeps, pkg_fingerprint: Option<&dyn Fn() -> CargoResult<String>>| {
             if deps.rerun_if_changed.is_empty() && deps.rerun_if_env_changed.is_empty() {
@@ -1726,7 +1750,12 @@ fn build_script_local_fingerprints(
             // Ok so now we're in "new mode" where we can have files listed as
             // dependencies as well as env vars listed as dependencies. Process
             // them all here.
-            Ok(Some(local_fingerprints_deps(deps, &target_dir, &pkg_root)))
+            Ok(Some(local_fingerprints_deps(
+                deps,
+                &target_dir,
+                &pkg_root,
+                &env_config,
+            )))
         };
 
     // Note that `false` == "not overridden"
@@ -1761,6 +1790,7 @@ fn local_fingerprints_deps(
     deps: &BuildDeps,
     target_root: &Path,
     pkg_root: &Path,
+    env_config: &Arc<HashMap<String, OsString>>,
 ) -> Vec<LocalFingerprint> {
     debug!("new local fingerprints deps {:?}", pkg_root);
     let mut local = Vec::new();
@@ -1781,11 +1811,11 @@ fn local_fingerprints_deps(
             .collect();
         local.push(LocalFingerprint::RerunIfChanged { output, paths });
     }
-
+    let env_config_insensitive = Arc::new(LazyCell::new());
     local.extend(
         deps.rerun_if_env_changed
             .iter()
-            .map(LocalFingerprint::from_env),
+            .map(|s| LocalFingerprint::from_env(s, env_config, &env_config_insensitive)),
     );
 
     local

tests/testsuite/build_script_env.rs

@@ -422,6 +422,7 @@ fn env_config_rerun_if_changed() {
     );
     p.cargo("check")
         .with_stderr_data(str![[r#"
+[COMPILING] foo v0.0.1 ([ROOT]/foo)
 [FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s
 
 "#]])
@@ -473,6 +474,7 @@ fn insensitive_env_config_rerun_if_changed() {
     );
     p.cargo("check")
         .with_stderr_data(str![[r#"
+[COMPILING] foo v0.0.1 ([ROOT]/foo)
 [FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s
 
 "#]])
@@ -516,6 +518,7 @@ fn env_config_newly_added_rerun() {
     );
     p.cargo("check")
         .with_stderr_data(str![[r#"
+[COMPILING] foo v0.0.1 ([ROOT]/foo)
 [FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s
 
 "#]])