Make tempfile a normal dependency

compiler/rustc_codegen_gcc/Cargo.toml

@@ -23,6 +23,7 @@ default = ["master"]
 
 [dependencies]
 object = { version = "0.37.0", default-features = false, features = ["std", "read"] }
+tempfile = "3.20"
 gccjit = "2.7"
 #gccjit = { git = "https://github.com/rust-lang/gccjit.rs" }
 
@@ -32,7 +33,6 @@ gccjit = "2.7"
 [dev-dependencies]
 boml = "0.3.1"
 lang_tester = "0.8.0"
-tempfile = "3.20"
 
 [profile.dev]
 # By compiling dependencies with optimizations, performing tests gets much faster.

compiler/rustc_codegen_gcc/src/lib.rs

@@ -26,11 +26,9 @@
 #![deny(clippy::pattern_type_mismatch)]
 #![allow(clippy::needless_lifetimes, clippy::uninlined_format_args)]
 
-// Some "regular" crates we want to share with rustc
+// These crates are pulled from the sysroot because they are part of
+// rustc's public API, so we need to ensure version compatibility.
 extern crate smallvec;
-// FIXME(antoyo): clippy bug: remove the #[allow] when it's fixed.
-#[allow(unused_extern_crates)]
-extern crate tempfile;
 #[macro_use]
 extern crate tracing;