dont embed RUSTFLAGS in final binary (#1396)

Author: BoxyUwU

build.rs

@@ -36,6 +36,15 @@ fn main() {
         println!("cargo:rustc-cfg=has_coverage_attribute");
     }
     println!("cargo:rustc-check-cfg=cfg(has_coverage_attribute)");
+
+    if std::env::var("RUSTFLAGS")
+        .unwrap_or_default()
+        .contains("-Cprofile-use=")
+    {
+        println!("cargo:rustc-cfg=specified_profile_use");
+    }
+    println!("cargo:rustc-check-cfg=cfg(specified_profile_use)");
+
     generate_self_schema();
     println!("cargo:rustc-env=PROFILE={}", std::env::var("PROFILE").unwrap());
 }

src/lib.rs

@@ -98,7 +98,10 @@ pub fn build_info() -> String {
     format!(
         "profile={} pgo={}",
         env!("PROFILE"),
-        option_env!("RUSTFLAGS").unwrap_or("").contains("-Cprofile-use="),
+        // We use a `cfg!` here not `env!`/`option_env!` as those would
+        // embed `RUSTFLAGS` into the generated binary which causes problems
+        // with reproducable builds.
+        cfg!(specified_profile_use),
     )
 }