mir: Introduce an empty StmtDebugInfo

Author: dianqk

compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs

@@ -1162,12 +1162,12 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                 let opt_assignment_rhs_span =
                     self.find_assignments(local).first().map(|&location| {
                         if let Some(mir::Statement {
-                            source_info: _,
                             kind:
                                 mir::StatementKind::Assign(box (
                                     _,
                                     mir::Rvalue::Use(mir::Operand::Copy(place)),
                                 )),
+                            ..
                         }) = self.body[location.block].statements.get(location.statement_index)
                         {
                             self.body.local_decls[place.local].source_info.span

compiler/rustc_middle/src/mir/mod.rs

@@ -1713,7 +1713,7 @@ mod size_asserts {
     static_assert_size!(BasicBlockData<'_>, 128);
     static_assert_size!(LocalDecl<'_>, 40);
     static_assert_size!(SourceScopeData<'_>, 64);
-    static_assert_size!(Statement<'_>, 32);
+    static_assert_size!(Statement<'_>, 56);
     static_assert_size!(Terminator<'_>, 96);
     static_assert_size!(VarDebugInfo<'_>, 88);
     // tidy-alphabetical-end

compiler/rustc_middle/src/mir/statement.rs

@@ -14,17 +14,19 @@ use crate::ty::CoroutineArgsExt;
 pub struct Statement<'tcx> {
     pub source_info: SourceInfo,
     pub kind: StatementKind<'tcx>,
+    pub debug_info: Vec<StmtDebugInfo>,
 }
 
 impl<'tcx> Statement<'tcx> {
     /// Changes a statement to a nop. This is both faster than deleting instructions and avoids
     /// invalidating statement indices in `Location`s.
     pub fn make_nop(&mut self) {
+        // TODO: convert the stmt to debuginfo.
         self.kind = StatementKind::Nop
     }
 
     pub fn new(source_info: SourceInfo, kind: StatementKind<'tcx>) -> Self {
-        Statement { source_info, kind }
+        Statement { source_info, kind, debug_info: Vec::new() }
     }
 }
 
@@ -938,3 +940,6 @@ impl RawPtrKind {
         }
     }
 }
+
+#[derive(Debug, Clone, TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)]
+pub struct StmtDebugInfo {}

compiler/rustc_middle/src/mir/visit.rs

@@ -381,7 +381,8 @@ macro_rules! make_mir_visitor {
                 statement: & $($mutability)? Statement<'tcx>,
                 location: Location
             ) {
-                let Statement { source_info, kind } = statement;
+                // TODO: visit debuginfo
+                let Statement { source_info, kind, .. } = statement;
 
                 self.visit_source_info(source_info);
                 match kind {