coverage. Refactor MCDCInfoBuilder for pattern matching implementation

Author: zhuyunxing

compiler/rustc_middle/src/mir/coverage.rs

@@ -51,6 +51,14 @@ rustc_index::newtype_index! {
     pub struct ExpressionId {}
 }
 
+rustc_index::newtype_index! {
+    /// ID of a mcdc decision. Used to identify decision in a function.
+    #[derive(HashStable)]
+    #[encodable]
+    #[debug_format = "DecisionId({})"]
+    pub struct DecisionId {}
+}
+
 rustc_index::newtype_index! {
     /// ID of a mcdc condition. Used by llvm to check mcdc coverage.
     ///

compiler/rustc_mir_build/src/build/coverageinfo.rs

@@ -238,12 +238,11 @@ impl<'tcx> Builder<'_, 'tcx> {
 
         // Separate path for handling branches when MC/DC is enabled.
         if let Some(mcdc_info) = branch_info.mcdc_info.as_mut() {
-            let inject_block_marker = |source_info, block| {
-                branch_info.markers.inject_block_marker(&mut self.cfg, source_info, block)
-            };
+            let inject_block_marker =
+                |block| branch_info.markers.inject_block_marker(&mut self.cfg, source_info, block);
             mcdc_info.visit_evaluated_condition(
                 self.tcx,
-                source_info,
+                source_info.span,
                 then_block,
                 else_block,
                 inject_block_marker,