trans: Add early-out when translating unreachable controlflow expressions.

src/test/debuginfo/unreachable-locals.rs

@@ -26,6 +26,22 @@ fn after_return() {
         (a, ref b) => {}
     }
     for a in &[111i32] {}
+    let test = if some_predicate() { 1 } else { 2 };
+    while some_predicate() {
+        let abc = !some_predicate();
+    }
+    loop {
+        let abc = !some_predicate();
+        break;
+    }
+    // nested block
+    {
+        let abc = !some_predicate();
+
+        {
+            let def = !some_predicate();
+        }
+    }
 }
 
 fn after_panic() {
@@ -36,6 +52,22 @@ fn after_panic() {
         (a, ref b) => {}
     }
     for a in &[111i32] {}
+    let test = if some_predicate() { 1 } else { 2 };
+    while some_predicate() {
+        let abc = !some_predicate();
+    }
+    loop {
+        let abc = !some_predicate();
+        break;
+    }
+    // nested block
+    {
+        let abc = !some_predicate();
+
+        {
+            let def = !some_predicate();
+        }
+    }
 }
 
 fn after_diverging_function() {
@@ -46,6 +78,22 @@ fn after_diverging_function() {
         (a, ref b) => {}
     }
     for a in &[111i32] {}
+    let test = if some_predicate() { 1 } else { 2 };
+    while some_predicate() {
+        let abc = !some_predicate();
+    }
+    loop {
+        let abc = !some_predicate();
+        break;
+    }
+    // nested block
+    {
+        let abc = !some_predicate();
+
+        {
+            let def = !some_predicate();
+        }
+    }
 }
 
 fn after_break() {
@@ -57,18 +105,50 @@ fn after_break() {
             (a, ref b) => {}
         }
         for a in &[111i32] {}
+        let test = if some_predicate() { 1 } else { 2 };
+        while some_predicate() {
+            let abc = !some_predicate();
+        }
+        loop {
+            let abc = !some_predicate();
+            break;
+        }
+        // nested block
+        {
+            let abc = !some_predicate();
+
+            {
+                let def = !some_predicate();
+            }
+        }
     }
 }
 
 fn after_continue() {
     for _ in 0..10i32 {
-        break;
+        continue;
         let x = "0";
         let (ref y,z) = (1i32, 2u32);
         match (20i32, 'c') {
             (a, ref b) => {}
         }
         for a in &[111i32] {}
+        let test = if some_predicate() { 1 } else { 2 };
+        while some_predicate() {
+            let abc = !some_predicate();
+        }
+        loop {
+            let abc = !some_predicate();
+            break;
+        }
+        // nested block
+        {
+            let abc = !some_predicate();
+
+            {
+                let def = !some_predicate();
+            }
+        }
     }
 }
 
@@ -83,3 +163,6 @@ fn main() {
 fn diverge() -> ! {
     panic!();
 }
+
+fn some_predicate() -> bool { true || false }
+