Add environment variables for accessing the OUT_DIR

Author: namanlp

src/cargo/core/compiler/mod.rs

@@ -1706,10 +1706,15 @@ fn build_deps_args(
 
     for dep in deps {
         if dep.unit.mode.is_run_custom_build() {
-            cmd.env(
-                "OUT_DIR",
-                &build_runner.files().build_script_out_dir(&dep.unit),
-            );
+            let out_dir = &build_runner.files().build_script_out_dir(&dep.unit);
+            let mut out_dir_name = dep.unit.target.name().to_owned();
+            out_dir_name = out_dir_name
+                .strip_prefix("build-script-")
+                .unwrap_or(&out_dir_name)
+                .to_string();
+            out_dir_name.push_str("_OUT_DIR");
+            cmd.env("OUT_DIR", &out_dir);
+            cmd.env(&out_dir_name, &out_dir);
         }
     }
 

tests/testsuite/build_scripts_multiple.rs

@@ -549,7 +549,7 @@ fn build_script_with_conflicting_out_dirs() {
                 build = ["build1.rs", "build2.rs"]
             "#,
         )
-        // OUT_DIR is set to the lexicographically largest build script's OUT_DIR by default
+        // By default, OUT_DIR is set to that of the last build script in the array
         .file(
             "src/main.rs",
             r#"
@@ -628,7 +628,7 @@ fn build_script_with_conflicts_reverse_sorted() {
                 build = ["build2.rs", "build1.rs"]
             "#,
         )
-        // OUT_DIR is set to the lexicographically largest build script's OUT_DIR by default
+        // By default, OUT_DIR is set to that of the last build script in the array
         .file(
             "src/main.rs",
             r#"
@@ -785,9 +785,11 @@ fn multiple_out_dirs() {
         .file(
             "src/main.rs",
             r#"
-                include!(concat!(env!("OUT_DIR"), "/foo.rs"));
+                include!(concat!(env!("build1_OUT_DIR"), "/foo.rs"));
+                include!(concat!(env!("build2_OUT_DIR"), "/foo.rs"));
                 fn main() {
-                    println!("{}", message());
+                    println!("{}", message1());
+                    println!("{}", message2());
                 }
             "#,
         )
@@ -803,7 +805,7 @@ fn multiple_out_dirs() {
                 let dest_path = Path::new(&out_dir).join("foo.rs");
                 fs::write(
                     &dest_path,
-                    "pub fn message() -> &'static str {
+                    "pub fn message1() -> &'static str {
                         \"Hello, from Build Script 1!\"
                     }
                     "
@@ -822,7 +824,7 @@ fn multiple_out_dirs() {
                 let dest_path = Path::new(&out_dir).join("foo.rs");
                 fs::write(
                     &dest_path,
-                    "pub fn message() -> &'static str {
+                    "pub fn message2() -> &'static str {
                         \"Hello, from Build Script 2!\"
                     }
                     "
@@ -835,8 +837,105 @@ fn multiple_out_dirs() {
         .masquerade_as_nightly_cargo(&["multiple-build-scripts"])
         .with_status(0)
         .with_stdout_data(str![[r#"
+Hello, from Build Script 1!
 Hello, from Build Script 2!
 
 "#]])
         .run();
 }
+
+#[cargo_test]
+fn build_script_with_fn_conflicts() {
+    // In this, multiple scripts have duplicated/conflicting declarations of same function
+
+    let p = project()
+        .file(
+            "Cargo.toml",
+            r#"
+                cargo-features = ["multiple-build-scripts"]
+
+                [package]
+                name = "foo"
+                version = "0.1.0"
+                edition = "2024"
+
+                build = ["build1.rs", "build2.rs"]
+            "#,
+        )
+        .file(
+            "src/main.rs",
+            r#"
+                include!(concat!(env!("build1_OUT_DIR"), "/foo.rs"));
+                include!(concat!(env!("build2_OUT_DIR"), "/foo.rs"));
+                fn main() {
+                    println!("{}", message());
+                }
+            "#,
+        )
+        .file(
+            "build1.rs",
+            r#"
+            use std::env;
+            use std::fs;
+            use std::path::Path;
+
+            fn main() {
+                let out_dir = env::var_os("OUT_DIR").unwrap();
+                let dest_path = Path::new(&out_dir).join("foo.rs");
+                fs::write(
+                    &dest_path,
+                    "pub fn message() -> &'static str {
+                        \"Hello, from Build Script 1!\"
+                    }
+                    "
+                ).unwrap();
+             }"#,
+        )
+        .file(
+            "build2.rs",
+            r#"
+            use std::env;
+            use std::fs;
+            use std::path::Path;
+
+            fn main() {
+                let out_dir = env::var_os("OUT_DIR").unwrap();
+                let dest_path = Path::new(&out_dir).join("foo.rs");
+                fs::write(
+                    &dest_path,
+                    "pub fn message() -> &'static str {
+                        \"Hello, from Build Script 2!\"
+                    }
+                    "
+                ).unwrap();
+             }"#,
+        )
+        .build();
+
+    p.cargo("check -v")
+        .masquerade_as_nightly_cargo(&["multiple-build-scripts"])
+        .with_status(101)
+        .with_stderr_data(str![[r#"
+[COMPILING] foo v0.1.0 ([ROOT]/foo)
+...
+ --> [ROOT]/foo/target/debug/build/foo-[HASH]/out/foo.rs:1:1
+  |
+1 | pub fn message() -> &'static str {
+  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `message` redefined here
+  |
+ ::: [ROOT]/foo/target/debug/build/foo-[HASH]/out/foo.rs:1:1
+  |
+1 | pub fn message() -> &'static str {
+  | -------------------------------- previous definition of the value `message` here
+  |
+  = [NOTE] `message` must be defined only once in the value namespace of this module
+
+For more information about this error, try `rustc --explain E0428`.
+[ERROR] could not compile `foo` (bin "foo") due to 1 previous error
+
+Caused by:
+  process didn't exit successfully: `rustc --crate-name foo --edition=2024 src/main.rs [..] ([EXIT_STATUS]: 1)
+
+"#]])
+        .run();
+}