Rust: Account for variables bound in while let expressions

Author: hvitved

rust/ql/lib/codeql/rust/elements/internal/VariableImpl.qll

@@ -218,6 +218,13 @@ module Impl {
         scope = ce.getBody() and
         scope.getLocation().hasLocationInfo(_, line, column, _, _)
       )
+      or
+      exists(WhileExpr we, LetExpr let |
+        let.getPat() = pat and
+        we.getCondition() = let and
+        scope = we.getLoopBody() and
+        scope.getLocation().hasLocationInfo(_, line, column, _, _)
+      )
     )
   }
 

rust/ql/test/library-tests/variables/Cfg.expected

@@ -85,6 +85,15 @@ fn let_pattern4() {
     print_str(x5); // $ access=x5
 }
 
+fn let_pattern5() {
+    let s1 = Some(String::from("Hello!")); // s1
+
+    while let Some(ref s2) // s2
+        = s1 { // $ access=s1
+        print_str(s2); // $ access=s2
+    }
+}
+
 fn match_pattern1() {
     let x6 = Some(5); // x6
     let y1 = 10; // y1_1

rust/ql/test/library-tests/variables/variables.expected

@@ -3,12 +3,11 @@
 | main.rs:114:9:114:9 | k | Variable is not used. |
 | main.rs:141:5:141:5 | y | Variable is not used. |
 | main.rs:164:9:164:9 | x | Variable is not used. |
-| main.rs:170:9:170:9 | x | Variable is not used. |
+| main.rs:169:9:169:9 | x | Variable is not used. |
 | main.rs:174:9:174:9 | x | Variable is not used. |
-| main.rs:194:17:194:17 | a | Variable is not used. |
-| main.rs:202:20:202:22 | val | Variable is not used. |
-| main.rs:207:20:207:22 | val | Variable is not used. |
-| main.rs:214:14:214:16 | val | Variable is not used. |
-| main.rs:216:9:216:12 | None | Variable is not used. |
-| main.rs:225:9:225:12 | None | Variable is not used. |
-| main.rs:231:24:231:26 | val | Variable is not used. |
+| main.rs:195:17:195:17 | a | Variable is not used. |
+| main.rs:203:20:203:22 | val | Variable is not used. |
+| main.rs:216:14:216:16 | val | Variable is not used. |
+| main.rs:218:9:218:12 | None | Variable is not used. |
+| main.rs:227:9:227:12 | None | Variable is not used. |
+| main.rs:233:24:233:26 | val | Variable is not used. |

rust/ql/test/library-tests/variables/variables.rs

@@ -164,14 +164,15 @@ fn loops() {
     for x in 1..10 { // BAD: unused variable
     }
 
-    for _ in 1..10 {
-    }
+    for _ in 1..10 {}
 
-    for x in 1..10 { // SPURIOUS: unused variable [macros not yet supported]
+    for x // SPURIOUS: unused variable [macros not yet supported]
+    in 1..10 {    
         println!("x is {}", x);
     }
 
-    for x in 1..10 { // SPURIOUS: unused variable [macros not yet supported]
+    for x // SPURIOUS: unused variable [macros not yet supported]
+    in 1..10 {   
         assert!(x != 11);
     }
 }
@@ -199,20 +200,21 @@ fn if_lets() {
     }
 
     let mut next = Some(30);
-    while let Some(val) = next { // BAD: unused variable
+    while let Some(val) = next // BAD: unused variable
+    {
         next = None;
     }
 
     let mut next2 = Some(40);
-    while let Some(val) = next2 { // SPURIOUS: unused variable 'val'
+    while let Some(val) = next2 {
         total += val;
         next2 = None;
     }
 
     let c = Some(60);
     match c {
         Some(val) => { // BAD: unused variable
-        },
+        }
         None => { // SPURIOUS: unused variable 'None'
         }
     }
@@ -221,25 +223,22 @@ fn if_lets() {
     match d {
         Some(val) => {
             total += val;
-        },
+        }
         None => { // SPURIOUS: unused variable 'None'
         }
     }
 
     let e = MyOption::Some(80);
     match e {
         MyOption::Some(val) => { // BAD: unused variable
-        },
-        MyOption::None => {
         }
+        MyOption::None => {}
     }
 
     let f = YesOrNo::Yes;
     match f {
-        YesOrNo::Yes => {
-        },
-        YesOrNo::No => {
-        },
+        YesOrNo::Yes => {}
+        YesOrNo::No => {}
     }
 }