Auto merge of #112400 - WaffleLapkin:vtable_stats, r=compiler-errors

Collect VTable stats & add `-Zprint-vtable-sizes`

This is a bit hacky/buggy, but I'm not entirely sure how to fix it, so I want to ask reviewers for help...

To try this, use either of those:
- `cargo clean && RUSTFLAGS="-Zprint-vtable-sizes" cargo +toolchain b`
- `cargo clean && cargo rustc +toolchain -Zprint-vtable-sizes`
- `rustc +toolchain -Zprint-vtable-sizes ./file.rs`

1 files changed, 7 insertions, 0 deletions

diff --git a/compiler/rustc_driver_impl/src/lib.rs b/compiler/rustc_driver_impl/src/lib.rs
index 5b75205442b..f8dda23ef9c 100644
--- a/compiler/rustc_driver_impl/src/lib.rs
+++ b/compiler/rustc_driver_impl/src/lib.rs
@@ -430,6 +430,13 @@ fn run_compiler(
                 sess.code_stats.print_type_sizes();
             }
 
+            if sess.opts.unstable_opts.print_vtable_sizes {
+                let crate_name =
+                    compiler.session().opts.crate_name.as_deref().unwrap_or("<UNKNOWN_CRATE>");
+
+                sess.code_stats.print_vtable_sizes(crate_name);
+            }
+
             let linker = queries.linker()?;
             Ok(Some(linker))
         })?;