1 files changed, 106 insertions, 0 deletions
diff --git a/src/tools/rust-analyzer/crates/proc-macro-test/build.rs b/src/tools/rust-analyzer/crates/proc-macro-test/build.rs
new file mode 100644
index 000000000..a80c96261
--- /dev/null
+++ b/src/tools/rust-analyzer/crates/proc-macro-test/build.rs
@@ -0,0 +1,106 @@
+//! This will build the proc macro in `imp`, and copy the resulting dylib artifact into the
+//! `OUT_DIR`.
+//!
+//! `proc-macro-test` itself contains only a path to that artifact.
+//!
+//! The `PROC_MACRO_TEST_TOOLCHAIN` environment variable can be exported to use
+//! a specific rustup toolchain: this allows testing against older ABIs (e.g.
+//! 1.58) and future ABIs (stage1, nightly)
+
+use std::{
+    env, fs,
+    path::{Path, PathBuf},
+    process::Command,
+};
+
+use cargo_metadata::Message;
+
+fn main() {
+    println!("cargo:rerun-if-changed=imp");
+    println!("cargo:rerun-if-env-changed=PROC_MACRO_TEST_TOOLCHAIN");
+
+    let out_dir = env::var_os("OUT_DIR").unwrap();
+    let out_dir = Path::new(&out_dir);
+
+    let name = "proc-macro-test-impl";
+    let version = "0.0.0";
+
+    let imp_dir = std::env::current_dir().unwrap().join("imp");
+
+    let staging_dir = out_dir.join("proc-macro-test-imp-staging");
+    // this'll error out if the staging dir didn't previously exist. using
+    // `std::fs::exists` would suffer from TOCTOU so just do our best to
+    // wipe it and ignore errors.
+    let _ = std::fs::remove_dir_all(&staging_dir);
+
+    println!("Creating {}", staging_dir.display());
+    std::fs::create_dir_all(&staging_dir).unwrap();
+
+    let src_dir = staging_dir.join("src");
+    println!("Creating {}", src_dir.display());
+    std::fs::create_dir_all(src_dir).unwrap();
+
+    for item_els in [&["Cargo.toml"][..], &["src", "lib.rs"]] {
+        let mut src = imp_dir.clone();
+        let mut dst = staging_dir.clone();
+        for el in item_els {
+            src.push(el);
+            dst.push(el);
+        }
+        println!("Copying {} to {}", src.display(), dst.display());
+        std::fs::copy(src, dst).unwrap();
+    }
+
+    let target_dir = out_dir.join("target");
+
+    let mut cmd = if let Ok(toolchain) = std::env::var("PROC_MACRO_TEST_TOOLCHAIN") {
+        // leverage rustup to find user-specific toolchain
+        let mut cmd = Command::new("cargo");
+        cmd.arg(format!("+{toolchain}"));
+        cmd
+    } else {
+        Command::new(toolchain::cargo())
+    };
+
+    cmd.current_dir(&staging_dir)
+        .args(&["build", "-p", "proc-macro-test-impl", "--message-format", "json"])
+        // Explicit override the target directory to avoid using the same one which the parent
+        // cargo is using, or we'll deadlock.
+        // This can happen when `CARGO_TARGET_DIR` is set or global config forces all cargo
+        // instance to use the same target directory.
+        .arg("--target-dir")
+        .arg(&target_dir);
+
+    println!("Running {:?}", cmd);
+
+    let output = cmd.output().unwrap();
+    if !output.status.success() {
+        println!("proc-macro-test-impl failed to build");
+        println!("============ stdout ============");
+        println!("{}", String::from_utf8_lossy(&output.stdout));
+        println!("============ stderr ============");
+        println!("{}", String::from_utf8_lossy(&output.stderr));
+        panic!("proc-macro-test-impl failed to build");
+    }
+
+    let mut artifact_path = None;
+    for message in Message::parse_stream(output.stdout.as_slice()) {
+        match message.unwrap() {
+            Message::CompilerArtifact(artifact) => {
+                if artifact.target.kind.contains(&"proc-macro".to_string()) {
+                    let repr = format!("{} {}", name, version);
+                    if artifact.package_id.repr.starts_with(&repr) {
+                        artifact_path = Some(PathBuf::from(&artifact.filenames[0]));
+                    }
+                }
+            }
+            _ => (), // Unknown message
+        }
+    }
+
+    // This file is under `target_dir` and is already under `OUT_DIR`.
+    let artifact_path = artifact_path.expect("no dylib for proc-macro-test-impl found");
+
+    let info_path = out_dir.join("proc_macro_test_location.txt");
+    fs::write(info_path, artifact_path.to_str().unwrap()).unwrap();
+}