feat: add CARGO_MANIFEST_PATH env variable

src/cargo/core/compiler/compilation.rs

@@ -356,6 +356,7 @@ impl<'gctx> Compilation<'gctx> {
         // in BuildContext::target_metadata()
         let rust_version = pkg.rust_version().as_ref().map(ToString::to_string);
         cmd.env("CARGO_MANIFEST_DIR", pkg.root())
+            .env("CARGO_MANIFEST_PATH", pkg.manifest_path())
             .env("CARGO_PKG_VERSION_MAJOR", &pkg.version().major.to_string())
             .env("CARGO_PKG_VERSION_MINOR", &pkg.version().minor.to_string())
             .env("CARGO_PKG_VERSION_PATCH", &pkg.version().patch.to_string())

src/cargo/core/compiler/custom_build.rs

@@ -279,6 +279,7 @@ fn build_work(build_runner: &mut BuildRunner<'_, '_>, unit: &Unit) -> CargoResul
     let debug = unit.profile.debuginfo.is_turned_on();
     cmd.env("OUT_DIR", &script_out_dir)
         .env("CARGO_MANIFEST_DIR", unit.pkg.root())
+        .env("CARGO_MANIFEST_PATH", unit.pkg.manifest_path())
         .env("NUM_JOBS", &bcx.jobs().to_string())
         .env("TARGET", bcx.target_data.short_name(&unit.kind))
         .env("DEBUG", debug.to_string())

src/doc/src/reference/environment-variables.md

@@ -225,7 +225,8 @@ Note that if one of these values is not provided in the manifest, the
 corresponding environment variable is set to the empty string, `""`.
 
 * `CARGO` --- Path to the `cargo` binary performing the build.
-* `CARGO_MANIFEST_DIR` --- The directory containing the manifest of your package.
+* `CARGO_MANIFEST_DIR` --- The directory containing the manifest of your package. When running a [Cargo script], this variable will be set to the script location.
+* `CARGO_MANIFEST_PATH` --- The path to the manifest of your package.
 * `CARGO_PKG_VERSION` --- The full version of your package.
 * `CARGO_PKG_VERSION_MAJOR` --- The major version of your package.
 * `CARGO_PKG_VERSION_MINOR` --- The minor version of your package.
@@ -274,6 +275,7 @@ corresponding environment variable is set to the empty string, `""`.
 [examples]: cargo-targets.md#examples
 [integration test]: cargo-targets.md#integration-tests
 [`env` macro]: ../../std/macro.env.html
+[Cargo script]: unstable.md#script
 
 ### Dynamic library paths
 
@@ -320,6 +322,7 @@ let out_dir = env::var("OUT_DIR").unwrap();
 * `CARGO_MANIFEST_DIR` --- The directory containing the manifest for the package
   being built (the package containing the build script). Also note that this is
   the value of the current working directory of the build script when it starts.
+* `CARGO_MANIFEST_PATH` --- The path to the manifest of your package.
 * `CARGO_MANIFEST_LINKS` --- the manifest `links` value.
 * `CARGO_MAKEFLAGS` --- Contains parameters needed for Cargo's [jobserver]
   implementation to parallelize subprocesses. Rustc or cargo invocations from

src/doc/src/reference/unstable.md

@@ -1460,7 +1460,7 @@ This will not affect any hard-coded paths in the source code, such as in strings
     Values in a non-empty array would be joined into a comma-separated list.
     If the build script introduces absolute paths to built artifacts (such as by invoking a compiler),
     the user may request them to be sanitized in different types of artifacts.
-    Common paths requiring sanitization include `OUT_DIR` and `CARGO_MANIFEST_DIR`,
+    Common paths requiring sanitization include `OUT_DIR`, `CARGO_MANIFEST_DIR` and `CARGO_MANIFEST_PATH`,
     plus any other introduced by the build script, such as include directories.
 
 ## gc

tests/testsuite/script.rs

@@ -1317,3 +1317,33 @@ fn cmd_publish_with_embedded() {
 "#]])
         .run();
 }
+
+#[cargo_test]
+fn manifest_path_env() {
+    let p = cargo_test_support::project()
+        .file(
+            "script.rs",
+            r#"#!/usr/bin/env cargo
+
+fn main() {
+    let path = env!("CARGO_MANIFEST_PATH");
+    println!("CARGO_MANIFEST_PATH: {}", path);
+}
+"#,
+        )
+        .build();
+    p.cargo("-Zscript -v script.rs")
+        .masquerade_as_nightly_cargo(&["script"])
+        .with_stdout_data(str![[r#"
+CARGO_MANIFEST_PATH: [ROOT]/foo/script.rs
+
+"#]])
+        .with_stderr_data(str![[r#"
+[WARNING] `package.edition` is unspecified, defaulting to `2021`
+[COMPILING] script v0.0.0 ([ROOT]/foo)
+[FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s
+[RUNNING] `[ROOT]/home/.cargo/target/[HASH]/debug/script[EXE]`
+
+"#]])
+        .run();
+}