Add prefix to every line of `-Zhir-stats` output.

This is based on `-Zprint-type-sizes` which does the same thing. It
makes the output provenance clearer, and helps with post-processing.
E.g. if you have `-Zhir-stats` output from numerous compiler invocations
you can now easily extract the pre-expansion stats separately from the
post-expansion stats.

1 files changed, 2 insertions, 2 deletions

diff --git a/compiler/rustc_interface/src/passes.rs b/compiler/rustc_interface/src/passes.rs
index 66c6a229b89..1d083f3ec80 100644
--- a/compiler/rustc_interface/src/passes.rs
+++ b/compiler/rustc_interface/src/passes.rs
@@ -69,7 +69,7 @@ pub fn parse<'a>(sess: &'a Session, input: &Input) -> PResult<'a, ast::Crate> {
     }
 
     if sess.opts.unstable_opts.hir_stats {
-        hir_stats::print_ast_stats(&krate, "PRE EXPANSION AST STATS");
+        hir_stats::print_ast_stats(&krate, "PRE EXPANSION AST STATS", "ast-stats-1");
     }
 
     Ok(krate)
@@ -416,7 +416,7 @@ pub fn configure_and_expand(
     }
 
     if sess.opts.unstable_opts.hir_stats {
-        hir_stats::print_ast_stats(&krate, "POST EXPANSION AST STATS");
+        hir_stats::print_ast_stats(&krate, "POST EXPANSION AST STATS", "ast-stats-2");
     }
 
     resolver.resolve_crate(&krate);