[Heavy] Propagate source locations in template expansions

Author: ricejasonf

heavy/lib/OpEval.cpp

@@ -264,7 +264,8 @@ class OpEvalImpl {
   }
 
   BlockItrTy Visit(ApplyOp Op) {
-    Context.setLoc(getSourceLocation(Op.getLoc()));
+    heavy::SourceLocation Loc = getSourceLocation(Op.getLoc());
+    Context.setLoc(Loc);
 
     heavy::Value Callee = getValue(Op.getFn());
     ValueRefs Args;
@@ -296,10 +297,10 @@ class OpEvalImpl {
   }
 
   BlockItrTy Visit(ConsOp Op) {
-    // TODO Use PairWithSource to retain source location information.
     heavy::Value A = getValue(Op.getA());
     heavy::Value B = getValue(Op.getB());
-    heavy::Pair* V = Context.CreatePair(A, B);
+    heavy::SourceLocation Loc = getSourceLocation(Op.getLoc());
+    heavy::Pair* V = Context.CreatePairWithSource(A, B, Loc);
     setValue(Op.getResult(), V);
     return next(Op);
   }

heavy/lib/OpGen.cpp

@@ -1116,6 +1116,7 @@ mlir::Value OpGen::createCall(heavy::SourceLocation Loc, mlir::Value Fn,
   for (mlir::Value& Arg : Args)
     Arg = LocalizeValue(Arg);
 
+  assert(Loc.isValid() && "expecting a valid location for call");
   auto Op = create<ApplyOp>(Loc, Fn, Args);
 
   if (IsTailPos) return mlir::Value();