Set the .comment section

Author: antoyo

Cargo.lock

@@ -39,6 +39,8 @@ extern crate rustc_errors;
 extern crate rustc_fluent_macro;
 extern crate rustc_fs_util;
 extern crate rustc_hir;
+#[cfg(feature="master")]
+extern crate rustc_interface;
 extern crate rustc_macros;
 extern crate rustc_metadata;
 extern crate rustc_middle;
@@ -86,7 +88,7 @@ use std::sync::atomic::Ordering;
 
 use gccjit::{Context, OptimizationLevel};
 #[cfg(feature="master")]
-use gccjit::TargetInfo;
+use gccjit::{TargetInfo, Version};
 #[cfg(not(feature="master"))]
 use gccjit::CType;
 use errors::LTONotSupported;
@@ -249,6 +251,16 @@ fn new_context<'gcc, 'tcx>(tcx: &TyCtxt<'tcx>) -> Context<'gcc> {
     if tcx.sess.target.arch == "x86" || tcx.sess.target.arch == "x86_64" {
         context.add_command_line_option("-masm=intel");
     }
+    #[cfg(feature="master")]
+    {
+        let version = Version::get();
+        let version = format!("{}.{}.{}", version.major, version.minor, version.patch);
+        context.set_output_ident(&format!("rustc version {} with libgccjit {}",
+                rustc_interface::util::rustc_version_str().unwrap_or("unknown version"),
+                version,
+        ));
+    }
+    // TODO(antoyo): check if this should only be added when using -Cforce-unwind-tables=n.
     context.add_command_line_option("-fno-asynchronous-unwind-tables");
     context
 }