Seed each function with a bunch of variables

generate/src/generation/mod.rs

@@ -481,6 +481,16 @@ impl GenerationCtx {
         local
     }
 
+    // Declare a bunch of variables when we first start a function
+    fn declare_seed_vars(&mut self) {
+        for tyid in self
+            .ty_weights
+            .choose_tys(self.rng.get_mut(), &self.tcx, self.tcx.len() / 3)
+        {
+            self.declare_new_var(Mutability::Mut, tyid);
+        }
+    }
+
     #[allow(dead_code)]
     fn generate_storage_live(&self) -> Result<Statement> {
         let local = self
@@ -1084,6 +1094,9 @@ impl GenerationCtx {
             args,
             return_dest,
         );
+
+        self.declare_seed_vars();
+
         new_fn
     }
 
@@ -1108,6 +1121,8 @@ impl GenerationCtx {
 
         self.pt
             .enter_fn0(&self.program.functions[self.cursor.function]);
+
+        self.declare_seed_vars();
     }
 
     // Returns from the currnt function. Returns false if we're returning from

generate/src/place_select.rs

@@ -179,6 +179,11 @@ impl PlaceSelector {
         pt.reachable_nodes().filter(move |ppath| {
             let index = ppath.target_index();
 
+            // Don't generate anything of unit type
+            if pt.ty(index) == TyCtxt::UNIT {
+                return false;
+            }
+
             // Well-typedness
             if let Some(tys) = &self.tys
                 && !tys.contains(&pt.ty(index))

generate/src/ty.rs

@@ -93,6 +93,14 @@ impl TySelect {
             .nth(self.weights.sample(rng))
             .expect("tyctxt isn't empty")
     }
+
+    pub fn choose_tys(&self, rng: &mut impl Rng, tcx: &TyCtxt, count: usize) -> Vec<TyId> {
+        (&self.weights)
+            .sample_iter(rng)
+            .take(count)
+            .map(|tyid| tcx.indices().nth(tyid).expect("tyctxt isn't empty"))
+            .collect()
+    }
 }
 
 fn new_composite(tcx: &mut TyCtxt, rng: &mut impl Rng) {