check casts

1 files changed, 19 insertions, 3 deletions

diff --git a/src/parse.cff b/src/parse.cff
index 752165b..d0c3da7 100644
--- a/src/parse.cff
+++ b/src/parse.cff
@@ -1780,11 +1780,27 @@ fn pexprefix(P *Parser) Expr {
    case lexmatch(P, &tok, :kw_as);
       let loc = tok.loc;
       lexexpect(P, '(');
-      let ty = parsetype(P);
+      let to = parsetype(P);
       lexexpect(P, ')');
       let ex = pexprefix(P);
-      // TODO check valid cast
-      return { loc, ty, :Cast(exprdup(P.alloc, ex)) };
+      let from = ex.ty;
+      switch {
+      case to->is(:Arr) and to.u.Arr.length < 0 and ex.u.#tag == :ArrIni;
+         ex.ty = (to = mkarrtype(ex.u.ArrIni.maxn + 1, #f, to.u.Arr.child));
+      case typeof2(to, from);
+      case to->is(:Int) and from->is(:Ptr) and to.size == from.size;
+      case to->is(:Ptr) and from->is(:Int) and to.size == from.size;
+      case to->is(:Ptr) and from->is(:Ptr);
+      case to->is(:Flo) and from->is(:Int);
+      case to->is(:Int) and from->is(:Flo);
+      case to->is(:Int) and from->is(:Bool);
+      case to->is(:Bool) and from->is(:Int);
+      case to->is(:Int) and from->is(:Enum);
+      case to->is(:Enum) and from->is(:Int);
+      case else
+         err(P, loc, "invalid cast from %t to %t", from, to);
+      }
+      return { loc, to, :Cast(exprdup(P.alloc, ex)) };
    }
    return pexpostfix(P);
 }