Update lints and tests

Author: cgm616

clippy_lints/src/xor_used_as_pow.rs

@@ -43,12 +43,6 @@ declare_lint_pass!(XorUsedAsPow => [XOR_USED_AS_POW]);
 
 impl LateLintPass<'_> for XorUsedAsPow {
     fn check_expr(&mut self, cx: &LateContext<'_>, expr: &'_ Expr<'_>) {
-        // TODO:
-        //  [ ] catch statements with literal or constant variables in rhs
-        //  [x] check for overflows on suggested changes
-        //  [x] ignore binary, octal, and hex literals in either side
-        //  [x] avoid linting on enum discriminants
-
         let parent_id = cx.tcx.hir().get_parent_item(expr.hir_id);
         if let Some(Node::Item(parent_item)) = cx.tcx.hir().find(parent_id) {
             if let ItemKind::Enum(_, _) = parent_item.kind {
@@ -128,7 +122,7 @@ fn report_with_ident(cx: &LateContext<'_>, lhs: u128, rhs: &QPath<'_>, span: Spa
     match lhs {
         2 => {
             let ident = last_path_segment(rhs).ident.name.to_ident_string();
-            report_pow_of_two(cx, "1", &ident, span);
+            report_pow_of_two(cx, format!("1 << {}", ident), span);
         },
         10 => report_pow_of_ten(cx, span),
         _ => {},
@@ -141,6 +135,11 @@ fn report_with_lit(cx: &LateContext<'_>, lhs: u128, rhs: u128, span: Span) {
     }
     match lhs {
         2 => {
+            if rhs == 0 {
+                report_pow_of_two(cx, format!("1"), span);
+                return;
+            }
+
             let lhs_str = if rhs <= 31 {
                 "1_u32"
             } else if rhs <= 63 {
@@ -149,21 +148,21 @@ fn report_with_lit(cx: &LateContext<'_>, lhs: u128, rhs: u128, span: Span) {
                 "1_u127"
             };
 
-            report_pow_of_two(cx, lhs_str, &rhs.to_string(), span);
+            report_pow_of_two(cx, format!("{} << {}", lhs_str, rhs), span);
         },
         10 => report_pow_of_ten(cx, span),
         _ => {},
     }
 }
 
-fn report_pow_of_two(cx: &LateContext<'_>, lhs: &str, rhs: &str, span: Span) {
+fn report_pow_of_two(cx: &LateContext<'_>, sugg: String, span: Span) {
     span_lint_and_sugg(
         cx,
         XOR_USED_AS_POW,
         span,
         "it appears you are trying to get a power of two, but `^` is not an exponentiation operator",
-        "use a bitshift instead",
-        format!("{} << {}", lhs, rhs),
+        "use a bitshift or constant instead",
+        sugg,
         Applicability::MaybeIncorrect,
     )
 }

tests/ui/xor_used_as_pow.stderr

@@ -2,7 +2,7 @@ error: it appears you are trying to get a power of two, but `^` is not an expone
   --> $DIR/xor_used_as_pow.rs:22:13
    |
 LL |     let _ = 2 ^ 3;
-   |             ^^^^^ help: use a bitshift instead: `1_u32 << 3`
+   |             ^^^^^ help: use a bitshift or constant instead: `1_u32 << 3`
    |
    = note: `-D clippy::xor-used-as-pow` implied by `-D warnings`
 
@@ -18,7 +18,7 @@ error: it appears you are trying to get a power of two, but `^` is not an expone
   --> $DIR/xor_used_as_pow.rs:24:13
    |
 LL |     let _ = 2 ^ 32;
-   |             ^^^^^^ help: use a bitshift instead: `1_u64 << 32`
+   |             ^^^^^^ help: use a bitshift or constant instead: `1_u64 << 32`
 
 error: the operation is ineffective. Consider reducing it to `2`
   --> $DIR/xor_used_as_pow.rs:25:13
@@ -32,7 +32,7 @@ error: it appears you are trying to get a power of two, but `^` is not an expone
   --> $DIR/xor_used_as_pow.rs:25:13
    |
 LL |     let _ = 2 ^ 0;
-   |             ^^^^^ help: try: `1`
+   |             ^^^^^ help: use a bitshift or constant instead: `1`
 
 error: the operation is ineffective. Consider reducing it to `10`
   --> $DIR/xor_used_as_pow.rs:26:13
@@ -48,19 +48,19 @@ LL |     let _ = 10 ^ 0;
    |
    = help: did you mean to use .pow()?
 
-error: aborting due to 7 previous errors
-
 error: it appears you are trying to get a power of two, but `^` is not an exponentiation operator
   --> $DIR/xor_used_as_pow.rs:29:17
    |
 LL |         let _ = 2 ^ x;
-   |                  ^^^^ help: use a bitshift instead: `1_u32 << 15`
+   |                 ^^^^^ help: use a bitshift or constant instead: `1 << x`
 
 error: `^` is not an exponentiation operator but appears to have been used as one
   --> $DIR/xor_used_as_pow.rs:30:17
    |
 LL |         let _ = 10 ^ x;
-   |                  ^^^^^
+   |                 ^^^^^^
    |
    = help: did you mean to use .pow()?
 
+error: aborting due to 9 previous errors
+