Replace `ExpressionOperandId` with enum `Operand`

Because the three kinds of operand are now distinguished explicitly, we no
longer need fiddly code to disambiguate counter IDs and expression IDs based on
the total number of counters/expressions in a function.

This does increase the size of operands from 4 bytes to 8 bytes, but that
shouldn't be a big deal since they are mostly stored inside boxed structures,
and the current coverage code is not particularly size-optimized anyway.

1 files changed, 1 insertions, 1 deletions

diff --git a/compiler/rustc_mir_transform/src/coverage/mod.rs b/compiler/rustc_mir_transform/src/coverage/mod.rs
index 076e714d703..f713613d313 100644
--- a/compiler/rustc_mir_transform/src/coverage/mod.rs
+++ b/compiler/rustc_mir_transform/src/coverage/mod.rs
@@ -304,7 +304,7 @@ impl<'a, 'tcx> Instrumentor<'a, 'tcx> {
             let counter_kind = if let Some(&counter_operand) = bcb_counters[bcb].as_ref() {
                 self.coverage_counters.make_identity_counter(counter_operand)
             } else if let Some(counter_kind) = self.bcb_data_mut(bcb).take_counter() {
-                bcb_counters[bcb] = Some(counter_kind.as_operand_id());
+                bcb_counters[bcb] = Some(counter_kind.as_operand());
                 debug_used_expressions.add_expression_operands(&counter_kind);
                 counter_kind
             } else {