upgrade direct use of rand

Author: FauxFaux

Cargo.lock

@@ -30,7 +30,8 @@ num-traits = "0.2.8"
 num-integer = "0.1.41"
 num-rational = "0.2.2"
 num-iter = "0.1.39"
-rand = "0.5"
+rand = "0.7"
+rand_distr = "0.2"
 log = "0.3"
 rustpython-derive = {path = "../derive", version = "0.1.1"}
 rustpython-parser = {path = "../parser", optional = true, version = "0.1.1"}

vm/Cargo.toml

@@ -1,6 +1,7 @@
 //! Random module.
 
-use rand::distributions::{Distribution, Normal};
+use rand::distributions::Distribution;
+use rand_distr::Normal;
 
 use crate::function::PyFuncArgs;
 use crate::obj::objfloat;
@@ -34,7 +35,12 @@ fn random_normalvariate(vm: &VirtualMachine, args: PyFuncArgs) -> PyResult {
     );
     let mu = objfloat::get_value(mu);
     let sigma = objfloat::get_value(sigma);
-    let normal = Normal::new(mu, sigma);
+    let normal = Normal::new(mu, sigma).map_err(|rand_err| {
+        vm.new_exception(
+            vm.ctx.exceptions.arithmetic_error.clone(),
+            format!("invalid normal distribution: {:?}", rand_err),
+        )
+    })?;
     let value = normal.sample(&mut rand::thread_rng());
     let py_value = vm.ctx.new_float(value);
     Ok(py_value)