Do match-check before const MIR generation

Author: sinkuu

src/librustc/ich/impls_ty.rs

@@ -371,7 +371,8 @@ for ::middle::const_val::ErrKind<'gcx> {
             MiscBinaryOp |
             MiscCatchAll |
             IndexOpFeatureGated |
-            TypeckError => {
+            TypeckError |
+            MatchCheckError => {
                 // nothing to do
             }
             UnimplementedConstVal(s) => {

src/librustc/middle/const_val.rs

@@ -106,7 +106,8 @@ pub enum ErrKind<'tcx> {
 
     ErroneousReferencedConstant(Box<ConstEvalErr<'tcx>>),
 
-    TypeckError
+    TypeckError,
+    MatchCheckError,
 }
 
 impl<'tcx> From<ConstMathErr> for ErrKind<'tcx> {
@@ -168,6 +169,7 @@ impl<'a, 'gcx, 'tcx> ConstEvalErr<'tcx> {
             ErroneousReferencedConstant(_) => simple!("could not evaluate referenced constant"),
 
             TypeckError => simple!("type-checking failed"),
+            MatchCheckError => simple!("match-checking failed"),
         }
     }
 
@@ -212,8 +214,9 @@ impl<'a, 'gcx, 'tcx> ConstEvalErr<'tcx> {
         primary_span: Span,
         primary_kind: &str)
     {
-        if let ErrKind::TypeckError = self.kind {
-            return;
+        match self.kind {
+            ErrKind::TypeckError | ErrKind::MatchCheckError => return,
+            _ => {}
         }
         self.struct_error(tcx, primary_span, primary_kind).emit();
     }

src/librustc/ty/structural_impls.rs

@@ -477,6 +477,7 @@ impl<'a, 'tcx> Lift<'tcx> for const_val::ErrKind<'a> {
             }
 
             TypeckError => TypeckError,
+            MatchCheckError => MatchCheckError,
         })
     }
 }

src/librustc_const_eval/eval.rs

@@ -705,8 +705,20 @@ fn const_eval<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
 
     let tables = tcx.typeck_tables_of(def_id);
     let body = if let Some(id) = tcx.hir.as_local_node_id(def_id) {
+        let body_id = tcx.hir.body_owned_by(id);
+
+        // Do match-check before building MIR
+        tcx.sess
+            .track_errors(|| super::check_match::check_body(tcx, def_id, body_id))
+            .map_err(|_| {
+                ConstEvalErr {
+                    span: tcx.def_span(key.value.0),
+                    kind: MatchCheckError,
+                }
+            })?;
+
         tcx.mir_const_qualif(def_id);
-        tcx.hir.body(tcx.hir.body_owned_by(id))
+        tcx.hir.body(body_id)
     } else {
         tcx.extern_const_body(def_id).body
     };