switch check

2 files changed, 29 insertions, 0 deletions

diff --git a/src/parse.cff b/src/parse.cff
index d0c3da7..2611906 100644
--- a/src/parse.cff
+++ b/src/parse.cff
@@ -2176,6 +2176,13 @@ fn pstiswitch(P *Parser, loc Loc, ex Expr) Stmt {
    let cs Vec<ISwitchCase> = {};
    let f Block = {};
    let elsep = #f;
+
+   let seen Map<i64, Loc, struct {
+      fn hash(x i64) u32 { return x; }
+      fn eq(a i64, b i64) bool { return a == b;}
+   }> = {};
+   defer seen->clear();
+
    while !lexmatch(P, &tok, '}') {
       lexexpect(P, :kw_case);
       if lexmatch(P, &tok, :kw_else) {
@@ -2196,6 +2203,10 @@ fn pstiswitch(P *Parser, loc Loc, ex Expr) Stmt {
          if !typematchestarg(ex.ty, e.ty) {
             err(P, e.loc, "bad case expression (%t, expected %t)", e.ty, ex.ty);
          }
+         if seen->get(e.u.IntLit.i) {
+            err(P, e.loc, "duplicate case expression (previously seen at %l)", *seen->get(e.u.IntLit.i));
+         }
+         seen->put(e.u.IntLit.i, e.loc);
          es->push(e);
          if !lexmatch(P, #null, ',') {
             lexexpect(P, ';');
@@ -2214,6 +2225,12 @@ fn psteuswitch(P *Parser, loc Loc, test Expr) Stmt {
    let f Block = {};
    let elsep = #f;
 
+   let seen Map<int, Loc, struct {
+      fn hash(x int) u32 { return x; }
+      fn eq(a int, b int) bool { return a == b;}
+   }> = {};
+   defer seen->clear();
+
    while !lexmatch(P, &tok, '}') {
       let c EUSwitchCase = {};
       lexexpect(P, :kw_case);
@@ -2231,6 +2248,12 @@ fn psteuswitch(P *Parser, loc Loc, test Expr) Stmt {
          fatal(P, tok.loc, "%t has no such variant %qT", test.ty, tok);
       }
       c.variant = c.fld - test.ty.u.Agg.flds.#ptr;
+
+      if seen->get(c.variant) {
+         err(P, tok.loc, "duplicate case expression (previously seen at %l)", *seen->get(c.variant));
+      }
+      seen->put(c.variant, tok.loc);
+
       if c.fld.ty != #null and lexmatch(P, &tok, '*') {
          if !islvalue(test) {
             fatal(P, tok.loc, "cannot capture by pointer, test expression is not lvalue");
diff --git a/src/set.hff b/src/set.hff
index 6a03e52..212d578 100644
--- a/src/set.hff
+++ b/src/set.hff
@@ -74,6 +74,12 @@ struct Set<T, Traits> {
    fn put(self *Set, x T) void {
       self->intern(x);
    }
+
+   fn clear(self *Set) void {
+      self.buf->clear();
+      free(self.set);
+      *self = {};
+   }
 }
 
 defmacro set_each(v, Set, &body) [