fix(fuzz): Prevent breaking/continuing out from let blocks in the AST fuzzer

tooling/ast_fuzzer/fuzz/src/targets/comptime_vs_brillig.rs

@@ -21,7 +21,7 @@ pub fn fuzz(u: &mut Unstructured) -> eyre::Result<()> {
         avoid_err_by_zero: true,
         // and it gets old to have to edit u128 to fit into u32 for the frontend to parse
         avoid_large_int_literals: true,
-        // Avoid break/continue (until #8382 is merged)
+        // Avoid break/continue
         avoid_loop_control: true,
         // Has to only use expressions valid in comptime
         comptime_friendly: true,

tooling/ast_fuzzer/src/program/func.rs

@@ -758,7 +758,14 @@
         let max_depth = self.max_depth();
         let comptime_friendly = self.is_comptime_friendly();
         let typ = self.ctx.gen_type(u, max_depth, false, false, true, comptime_friendly)?;
+
+        // Temporarily set in_loop to false to disallow breaking/continuing out
+        // of the let blocks (which would lead to frontend errors when reversing
+        // the AST into Noir)
+        let was_in_loop = std::mem::replace(&mut self.in_loop, false);
         let expr = self.gen_expr(u, &typ, max_depth, Flags::TOP)?;
+        self.in_loop = was_in_loop;
+
         let mutable = bool::arbitrary(u)?;
         Ok(self.let_var(mutable, typ, expr, true))
     }
@@ -1325,9 +1332,9 @@
     ctx.config.max_loop_size = 10;
     ctx.config.vary_loop_size = false;
     ctx.gen_main_decl(&mut u);
     let mut fctx = FunctionContext::new(&mut ctx, FuncId(0));
     fctx.budget = 2;
     let loop_code = format!("{}", fctx.gen_loop(&mut u).unwrap()).replace(" ", "");
 
     println!("{loop_code}");
     assert!(
@@ -1351,8 +1358,8 @@
     ctx.config.max_loop_size = 10;
     ctx.config.vary_loop_size = false;
     ctx.gen_main_decl(&mut u);
     let mut fctx = FunctionContext::new(&mut ctx, FuncId(0));
     fctx.budget = 2;
     let while_code = format!("{}", fctx.gen_while(&mut u).unwrap()).replace(" ", "");
 
     println!("{while_code}");