add `-Z dump-mono-stats`

This option will output some stats from the monomorphization collection
pass to a file, to show estimated sizes from each instantiation.

1 files changed, 6 insertions, 0 deletions

diff --git a/compiler/rustc_monomorphize/src/errors.rs b/compiler/rustc_monomorphize/src/errors.rs
index f1ca72de8db..f15cf54718e 100644
--- a/compiler/rustc_monomorphize/src/errors.rs
+++ b/compiler/rustc_monomorphize/src/errors.rs
@@ -77,3 +77,9 @@ pub struct SymbolAlreadyDefined {
     pub span: Option<Span>,
     pub symbol: String,
 }
+
+#[derive(Diagnostic)]
+#[diag(monomorphize_couldnt_dump_mono_stats)]
+pub struct CouldntDumpMonoStats {
+    pub error: String,
+}