Merge pull request #4587 from sanxiyn/divide-by-zero

Handle divide by zero in constant evaluator

Author: catamorphism

src/librustc/middle/const_eval.rs

@@ -295,7 +295,9 @@ fn eval_const_expr_partial(tcx: middle::ty::ctxt, e: @expr)
               add => Ok(const_int(a + b)),
               subtract => Ok(const_int(a - b)),
               mul => Ok(const_int(a * b)),
+              div if b == 0 => Err(~"divide by zero"),
               div => Ok(const_int(a / b)),
+              rem if b == 0 => Err(~"modulo zero"),
               rem => Ok(const_int(a % b)),
               and | bitand => Ok(const_int(a & b)),
               or | bitor => Ok(const_int(a | b)),
@@ -315,7 +317,9 @@ fn eval_const_expr_partial(tcx: middle::ty::ctxt, e: @expr)
               add => Ok(const_uint(a + b)),
               subtract => Ok(const_uint(a - b)),
               mul => Ok(const_uint(a * b)),
+              div if b == 0 => Err(~"divide by zero"),
               div => Ok(const_uint(a / b)),
+              rem if b == 0 => Err(~"modulo zero"),
               rem => Ok(const_uint(a % b)),
               and | bitand => Ok(const_uint(a & b)),
               or | bitor => Ok(const_uint(a | b)),

src/test/compile-fail/eval-enum.rs

@@ -0,0 +1,6 @@
+enum test {
+    div_zero = 1/0, //~ERROR expected constant: divide by zero
+    rem_zero = 1%0  //~ERROR expected constant: modulo zero
+}
+
+fn main() {}