Add more catch-related CFG and lifetime tests and fix CFG bug

Author: cramertj

src/librustc/cfg/construct.rs

@@ -87,7 +87,7 @@ impl<'a, 'tcx> CFGBuilder<'a, 'tcx> {
                 stmts_exit = self.stmt(stmt, stmts_exit);
             }
             let blk_expr_exit = self.opt_expr(&blk.expr, stmts_exit);
-            self.add_contained_edge(blk_expr_exit, blk_expr_exit);
+            self.add_contained_edge(blk_expr_exit, expr_exit);
 
             self.breakable_block_scopes.pop();
 

src/test/compile-fail/catch-bad-lifetime.rs

@@ -10,26 +10,34 @@
 
 #![feature(catch_expr)]
 
+// This test checks that borrows made and returned inside catch blocks are properly constrained
 pub fn main() {
-    let _: Result<(), &str> = do catch {
-        let my_string = String::from("");
-        let my_str: &str = &my_string;
-        Err(my_str)?;
-        Err("")?;
-        Ok(())
-    }; //~ ERROR `my_string` does not live long enough
+    {
+        // Test that borrows returned from a catch block must be valid for the lifetime of the
+        // result variable
+        let _result: Result<(), &str> = do catch {
+            let my_string = String::from("");
+            let my_str: & str = & my_string;
+            Err(my_str) ?;
+            Err("") ?;
+            Ok(())
+        }; //~ ERROR `my_string` does not live long enough
+    }
 
-    let mut i = 5;
-    let k = &mut i;
-    let mut j: Result<(), &mut i32> = do catch {
-        Err(k)?;
-        i = 10; //~ ERROR cannot assign to `i` because it is borrowed
-        Ok(())
-    };
-    ::std::mem::drop(k); //~ ERROR use of moved value: `k`
-    i = 40; //~ ERROR cannot assign to `i` because it is borrowed
+    {
+        // Test that borrows returned from catch blocks freeze their referent
+        let mut i = 5;
+        let k = &mut i;
+        let mut j: Result<(), &mut i32> = do catch {
+            Err(k) ?;
+            i = 10; //~ ERROR cannot assign to `i` because it is borrowed
+            Ok(())
+        };
+        ::std::mem::drop(k); //~ ERROR use of moved value: `k`
+        i = 40; //~ ERROR cannot assign to `i` because it is borrowed
 
-    let i_ptr = if let Err(i_ptr) = j { i_ptr } else { panic!("") };
-    *i_ptr = 50;
+        let i_ptr = if let Err(i_ptr) = j { i_ptr } else { panic ! ("") };
+        *i_ptr = 50;
+    }
 }
 

src/test/compile-fail/catch-maybe-bad-lifetime.rs

@@ -0,0 +1,51 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![feature(catch_expr)]
+
+// This test checks that borrows made and returned inside catch blocks are properly constrained
+pub fn main() {
+    {
+        // Test that a borrow which *might* be returned still freezes its referent
+        let mut i = 222;
+        let x: Result<&i32, ()> = do catch {
+            Err(())?;
+            Ok(&i)
+        };
+        x.ok().cloned();
+        i = 0; //~ ERROR cannot assign to `i` because it is borrowed
+        let _ = i;
+    }
+
+    {
+        let x = String::new();
+        let _y: Result<(), ()> = do catch {
+            Err(())?;
+            ::std::mem::drop(x);
+            Ok(())
+        };
+        println!("{}", x); //~ ERROR use of moved value: `x`
+    }
+
+    {
+        // Test that a borrow which *might* be assigned to an outer variable still freezes
+        // its referent
+        let mut i = 222;
+        let j;
+        let x: Result<(), ()> = do catch {
+            Err(())?;
+            j = &i;
+            Ok(())
+        };
+        i = 0; //~ ERROR cannot assign to `i` because it is borrowed
+        let _ = i;
+    }
+}
+

src/test/compile-fail/catch-opt-init.rs

@@ -10,11 +10,15 @@
 
 #![feature(catch_expr)]
 
+fn use_val<T: Sized>(_x: T) {}
+
 pub fn main() {
     let cfg_res;
     let _: Result<(), ()> = do catch {
         Err(())?;
         cfg_res = 5;
+        Ok::<(), ()>(())?;
+        use_val(cfg_res);
         Ok(())
     };
     assert_eq!(cfg_res, 5); //~ ERROR use of possibly uninitialized variable

src/test/run-pass/catch-expr.rs

@@ -58,6 +58,14 @@ pub fn main() {
     };
     assert_eq!(cfg_init, 5);
 
+    let cfg_init_2;
+    let _res: Result<(), ()> = do catch {
+        cfg_init_2 = 6;
+        Err(())?;
+        Ok(())
+    };
+    assert_eq!(cfg_init_2, 6);
+
     let my_string = "test".to_string();
     let res: Result<&str, ()> = do catch {
         Ok(&my_string)