improve liveness so it reports unused vars / dead assignments

doesn't warn about pattern bindings yet though

Author: nikomatsakis

src/rustc/middle/liveness.rs

@@ -1,9 +1,10 @@
-fn test(cond: bool) {
+fn test() {
     let v: int;
     v = 1; //! NOTE prior assignment occurs here
+    #debug["v=%d", v];
     v = 2; //! ERROR re-assignment of immutable variable
+    #debug["v=%d", v];
 }
 
 fn main() {
-    test(true);
 }

src/test/compile-fail/assign-imm-local-twice.rs

@@ -11,4 +11,5 @@ fn main() {
         x = some(i+1); //! ERROR assigning to mutable local variable prohibited due to outstanding loan
       }
     }
+    copy x; // just to prevent liveness warnings
 }

src/test/compile-fail/borrowck-pat-reassign-binding.rs

@@ -14,4 +14,5 @@ fn main() {
         x = some(1); //! ERROR assigning to mutable local variable prohibited due to outstanding loan
       }
     }
+    copy x; // just to prevent liveness warnings
 }

src/test/compile-fail/borrowck-pat-reassign-sometimes-binding.rs

@@ -1,11 +1,11 @@
-fn test(cond: bool) {
+fn test() {
     let v: int;
     loop {
         v = 1; //! ERROR re-assignment of immutable variable
         //!^ NOTE prior assignment occurs here
+        copy v; // just to prevent liveness warnings
     }
 }
 
 fn main() {
-    test(true);
 }

src/test/compile-fail/liveness-assign-imm-local-in-loop.rs

@@ -1,9 +1,9 @@
-fn test(cond: bool) {
+fn test() {
     let v: int;
     v = 2;  //! NOTE prior assignment occurs here
     v += 1; //! ERROR re-assignment of immutable variable
+    copy v;
 }
 
 fn main() {
-    test(true);
 }

src/test/compile-fail/liveness-assign-imm-local-in-op-eq.rs

@@ -0,0 +1,9 @@
+fn test() {
+    let v: int = 1; //! NOTE prior assignment occurs here
+    copy v;
+    v = 2; //! ERROR re-assignment of immutable variable
+    copy v;
+}
+
+fn main() {
+}

src/test/compile-fail/liveness-assign-imm-local-with-init.rs

@@ -1,9 +1,7 @@
 fn foo() -> int {
     let x: int;
-    let i: int;
 
     while 1 != 2  {
-        i = 0;
         break;
         x = 0; //! WARNING unreachable statement
     }

src/test/compile-fail/liveness-break-uninit-2.rs

@@ -1,9 +1,7 @@
 fn foo() -> int {
     let x: int;
-    let i: int;
 
     loop {
-        i = 0;
         break;
         x = 0;  //! WARNING unreachable statement
     }

src/test/compile-fail/liveness-break-uninit.rs

@@ -0,0 +1,20 @@
+fn f1(&x: int) {
+    x = 1; // no error
+}
+
+fn f2() {
+    let mut x = 3; //! WARNING value assigned to `x` is never read
+    x = 4;
+    copy x;
+}
+
+fn f3() {
+    let mut x = 3;
+    copy x;
+    x = 4; //! WARNING value assigned to `x` is never read
+}
+
+fn main() { // leave this in here just to trigger compile-fail:
+    let x: int;
+    copy x; //! ERROR use of possibly uninitialized variable: `x`
+}

src/test/compile-fail/liveness-dead.rs

@@ -5,4 +5,5 @@ type point = {x: int, y: int};
 fn main() {
     let mut origin: point;
     origin = {x: 10 with origin}; //! ERROR use of possibly uninitialized variable: `origin`
+    copy origin;
 }

src/test/compile-fail/liveness-init-in-fru.rs

@@ -1,8 +1,8 @@
-fn test(cond: bool) {
+fn test() {
     let v: int;
     v += 1; //! ERROR use of possibly uninitialized variable: `v`
+    copy v;
 }
 
 fn main() {
-    test(true);
 }

src/test/compile-fail/liveness-init-op-equal.rs

@@ -1,8 +1,8 @@
-fn test(cond: bool) {
+fn test() {
     let mut v: int;
     v = v + 1; //! ERROR use of possibly uninitialized variable: `v`
+    copy v;
 }
 
 fn main() {
-    test(true);
 }

src/test/compile-fail/liveness-init-plus-equal.rs

@@ -1,5 +1,5 @@
-fn main(s: [str]) {
+fn main(_s: [str]) {
     let a: [int] = [];
-    vec::each(a) { |x| //! ERROR not all control paths return a value
+    vec::each(a) { |_x| //! ERROR not all control paths return a value
     }
 }

src/test/compile-fail/liveness-issue-2163.rs

@@ -1,4 +1,4 @@
-fn take(-x: int) {}
+fn take(-_x: int) {}
 
 fn main() {
 

src/test/compile-fail/liveness-move-from-mode.rs

@@ -9,6 +9,8 @@ fn main() {
                 loop {
                     x <- y; //! ERROR use of moved variable
                     //!^ NOTE move of variable occurred here
+
+                    copy x;
                 }
             }
         }

src/test/compile-fail/liveness-move-in-loop.rs

@@ -4,7 +4,7 @@ fn main() {
     let mut x: int;
     loop {
         log(debug, y);
-        while true { while true { while true { x <- y; } } }
+        while true { while true { while true { x <- y; copy x; } } }
         //!^ ERROR use of moved variable: `y`
         //!^^ NOTE move of variable occurred here
     }

src/test/compile-fail/liveness-move-in-while.rs

@@ -1,5 +1,6 @@
 fn main() {
-	let x = 3;
-	let y;
-	x <-> y; //! ERROR use of possibly uninitialized variable: `y`
+    let mut x = 3;
+    let y;
+    x <-> y; //! ERROR use of possibly uninitialized variable: `y`
+    copy x;
 }

src/test/compile-fail/liveness-swap-uninit.rs

@@ -1,6 +1,6 @@
 fn main() {
     let bar;
-    fn baz(x: int) { }
+    fn baz(_x: int) { }
     bind baz(bar); //! ERROR use of possibly uninitialized variable: `bar`
 }
 

src/test/compile-fail/liveness-uninit-after-item.rs

@@ -0,0 +1,50 @@
+fn f1(x: int) {
+    //!^ WARNING unused variable: `x`
+    //!^^ WARNING unused variable x
+    // (the 2nd one is from tstate)
+}
+
+fn f1b(&x: int) {
+    //!^ WARNING unused variable: `x`
+    //!^^ WARNING unused variable x
+    // (the 2nd one is from tstate)
+}
+
+fn f2() {
+    let x = 3;
+    //!^ WARNING unused variable: `x`
+    //!^^ WARNING unused variable x
+    // (the 2nd one is from tstate)
+}
+
+fn f3() {
+    let mut x = 3;
+    //!^ WARNING unused variable: `x`
+    x += 4;
+    //!^ WARNING value assigned to `x` is never read
+}
+
+fn f3b() {
+    let mut z = 3;
+    //!^ WARNING unused variable: `z`
+    loop {
+        z += 4;
+    }
+}
+
+fn f4() {
+    alt some(3) {
+      some(i) {
+      }
+      none {}
+    }
+}
+
+// leave this in here just to trigger compile-fail:
+pure fn is_even(i: int) -> bool { (i%2) == 0 }
+fn even(i: int) : is_even(i) -> int { i }
+fn main() {
+    let i: int = 4;
+    log(debug, false && { check is_even(i); true });
+    even(i); //! ERROR unsatisfied precondition
+}

src/test/compile-fail/liveness-unused.rs

@@ -2,4 +2,5 @@ fn main() {
     let x = @5;
     let y <- x; //! NOTE move of variable occurred here
     log(debug, *x); //! ERROR use of moved variable: `x`
+    copy y;
 }

src/test/compile-fail/liveness-use-after-move.rs

@@ -8,7 +8,7 @@ enum _chan<T> = int;
 
 // Tests that "log(debug, message);" is flagged as using
 // message after the send deinitializes it
-fn test00_start(ch: _chan<int>, message: int, count: int) {
+fn test00_start(ch: _chan<int>, message: int, _count: int) {
     send(ch, message); //! NOTE move of variable occurred here
     log(debug, message); //! ERROR use of moved variable: `message`
 }

src/test/compile-fail/liveness-use-after-send.rs

@@ -2,9 +2,9 @@
 
 fn main() unsafe {
     fn foo(_a: uint, _b: uint) : uint::le(_a, _b) {}
-    let a: uint = 1u;
-    let b: uint = 4u;
-    let c: uint = 5u;
+    let mut a: uint = 1u;
+    let mut b: uint = 4u;
+    let mut c: uint = 5u;
     // make sure that the constraint le(b, a) exists...
     check (uint::le(b, a));
     // ...invalidate it...

src/test/compile-fail/no-constraint-prop.rs

@@ -7,9 +7,9 @@ fn f(a: int, b: int) : lt(a, b) { }
 pure fn lt(a: int, b: int) -> bool { ret a < b; }
 
 fn main() {
-    let a: int = 10;
-    let b: int = 23;
-    let c: int = 77;
+    let mut a: int = 10;
+    let mut b: int = 23;
+    let mut c: int = 77;
     check (lt(a, b));
     a = 24;
     f(a, b);

src/test/compile-fail/pred-assign.rs

@@ -7,9 +7,9 @@ fn f(a: int, b: int) : lt(a, b) { }
 pure fn lt(a: int, b: int) -> bool { ret a < b; }
 
 fn main() {
-    let a: int = 10;
-    let b: int = 23;
-    let c: int = 77;
+    let mut a: int = 10;
+    let mut b: int = 23;
+    let mut c: int = 77;
     check (lt(a, b));
     b <-> a;
     f(a, b);

src/test/compile-fail/pred-swap.rs

@@ -10,4 +10,5 @@ fn main() {
     origin = {x: 0, y: 0};
     let right: point = {x: 10 with tested(origin)};
         //!^ ERROR precondition
+    copy right;
 }

src/test/compile-fail/tstate-fru.rs

@@ -6,8 +6,8 @@ pure fn even(y: int) -> bool { true }
 
 fn main() {
 
-    let y: int = 42;
-    let x: int = 1;
+    let mut y: int = 42;
+    let mut x: int = 1;
     check (even(y));
     loop {
         print_even(y);

src/test/compile-fail/tstate-while-loop-unsat-constriants.rs

@@ -3,6 +3,6 @@
 enum foo { left({mut x: int}), right(bool) }
 
 fn main() {
-    let x = left({mut x: 10});
-    alt x { left(i) { x = right(false); log(debug, i); } _ { } }
+    let mut x = left({mut x: 10});
+    alt x { left(i) { x = right(false); copy x; log(debug, i); } _ { } }
 }