Be a bit more robust around path handling; support CARGO_TARGET_DIR

Author: gnzlbg

crates/libm-cdylib/src/test_utils.rs

@@ -51,27 +51,30 @@ where
     let mut cmd = process::Command::new(path);
 
     // Find the cdylib - we just support standard locations for now.
-    let libm_path = format!(
-        "../../target/{}/liblibm",
-        if cfg!(release_profile) {
-            "release"
-        } else {
-            "debug"
-        },
-    );
+    let target_dir = if let Ok(dir) = std::env::var("CARGO_TARGET_DIR") {
+        std::path::PathBuf::from(&dir)
+    } else {
+        Path::new("../../target").into()
+    };
+    let libm_path = target_dir.join(Path::new(if cfg!(release_profile) {
+        "release"
+    } else {
+        "debug"
+    }));
 
     // Replace libm at runtime
     if cfg!(target_os = "macos") {
+        let lib_name = format!("liblibm.{}", "dylib");
+        let lib_path = libm_path.join(Path::new(&lib_name));
         // for debugging:
         // cmd.env("DYLD_PRINT_LIBRARIES", "1");
         // cmd.env("X", "1");
         cmd.env("DYLD_FORCE_FLAT_NAMESPACE", "1");
-        cmd.env(
-            "DYLD_INSERT_LIBRARIES",
-            format!("{}.{}", libm_path, "dylib"),
-        );
+        cmd.env("DYLD_INSERT_LIBRARIES", lib_path.display().to_string());
     } else if cfg!(target_os = "linux") {
-        cmd.env("LD_PRELOAD", format!("{}.{}", libm_path, "so"));
+        let lib_name = format!("liblibm.{}", "so");
+        let lib_path = libm_path.join(Path::new(&lib_name));
+        cmd.env("LD_PRELOAD", lib_path.display().to_string());
     }
     // Run the binary:
     let output = cmd.output().unwrap();