# HG changeset patch
# User Simon Sapin <simon.sapin@octobus.net>
# Date 1621429707 -7200
# Node ID 402bd66cbdf2b97625d168240fe0dd6d46a88520
# Parent  18415fc918a14845f4507b1c8b366d9c67f6b902
rust: Add type annotation to fix inference on Rust Nightly

When compiling with Rust Nightly, the im-rs crate silently makes use of the
experimental language feature for trait impl specialization. This apperently
changes public its APIs in subtle ways such that type inference of some user
code can fail where it succeeds when specialization is disabled.

This made Mercurial’s Rust unit tests have compilation errors on Nightly.

I have not managed to find the exactl root cause, but I wrote down my findings
so far at https://github.com/bodil/im-rs/issues/188

This adds type annotation to make unit tests rely less on type inference
and work around the issue.

Differential Revision: https://phab.mercurial-scm.org/D10742

diff -r 18415fc918a1 -r 402bd66cbdf2 rust/hg-core/src/copy_tracing/tests_support.rs
--- a/rust/hg-core/src/copy_tracing/tests_support.rs	Wed May 19 13:45:34 2021 +0200
+++ b/rust/hg-core/src/copy_tracing/tests_support.rs	Wed May 19 15:08:27 2021 +0200
@@ -123,7 +123,10 @@
                     ),
                 )
             })
-            .collect::<OrdMap<_, _>>()
+            .collect::<OrdMap<
+                String,
+                (Revision, Option<String>, OrdSet<Revision>)
+            >>()
         }
     };
 }