Merge pull request rust-lang#1 from kraktus/pr-9506

Suggestions for rust-lang#9506

Author: blyxyas

clippy_lints/src/suspicious_xor.rs

@@ -1,8 +1,8 @@
 use clippy_utils::{numeric_literal::NumericLiteral, source::snippet};
-use rustc_ast::LitKind;
 use rustc_errors::Applicability;
 use rustc_hir::{BinOpKind, Expr, ExprKind, Lit};
-use rustc_lint::{LateContext, LateLintPass};
+use rustc_lint::{LateContext, LateLintPass, LintContext};
+use rustc_middle::lint::in_external_macro;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 
 declare_clippy_lint! {
@@ -27,61 +27,26 @@ declare_lint_pass!(ConfusingXorAndPow => [SUSPICIOUS_XOR]);
 
 impl LateLintPass<'_> for ConfusingXorAndPow {
     fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
-        if_chain! {
-            if let ExprKind::Binary(op, left, right) = &expr.kind;
-            if op.node == BinOpKind::BitXor;
-            if let ExprKind::Lit(litr) = &right.kind;
-            if let ExprKind::Lit(litl) = &left.kind;
-            if let snip_left = snippet(cx, litl.span, "..");
-            if let snip_right = snippet(cx, litr.span, "..");
-            if get_numlit(litr, &snip_right)
-            .zip(get_numlit(litl, &snip_left))
-            .map_or(false, |(a,b)| a.is_decimal() && b.is_decimal());
-            if let left_val = unwrap_lit_to_dec(left).unwrap_or(0);
-            if let right_val = unwrap_lit_to_dec(right).unwrap_or(0);
-            if let suffix = get_numlit(litr, &snip_right).unwrap().suffix.unwrap_or("");
-                then {
-
-                            if left_val == 2 &&
-                             (right_val == 8 ||
-                            right_val == 16 ||
-                            right_val == 32 ||
-                            right_val == 64 || right_val == 128)
-                            {
-                                clippy_utils::diagnostics::span_lint_and_sugg(
-                                    cx,
-                                    SUSPICIOUS_XOR,
-                                    expr.span,
-                                    "it appears that you are trying to get the maximum value of an integer, but '^' is not exponentiation operator",
-                                    "try with",
-                                    format!("u{right_val}::MAX"),
-                                    Applicability::MaybeIncorrect,
-                                );
-                            } else {
-                                // Even then, warn always.
-                                clippy_utils::diagnostics::span_lint_and_sugg(
-                                    cx,
-                                    SUSPICIOUS_XOR,
-                                    expr.span,
-                                    "'^' is not the exponentiation operator",
-                                    "did you mean to write",
-                                    format!("{left_val}{suffix}.pow({right_val})"),
-                                    Applicability::MaybeIncorrect,
-                                );
-                            }
-
-                    }
-        }
-    }
-}
-
-fn unwrap_lit_to_dec(expr: &Expr<'_>) -> Option<u128> {
-    match &expr.kind {
-        ExprKind::Lit(lit) => match lit.node {
-            LitKind::Int(num, _) => Some(num),
-            _ => None,
-        },
-        _ => None,
+        if !in_external_macro(cx.sess(), expr.span) &&
+            let ExprKind::Binary(op, left, right) = &expr.kind &&
+            op.node == BinOpKind::BitXor &&
+            let ExprKind::Lit(lit_left) = &left.kind &&
+            let ExprKind::Lit(lit_right) = &right.kind &&
+            let snip_left = snippet(cx, lit_left.span, "..") &&
+            let snip_right = snippet(cx, lit_right.span, "..") &&
+            let Some(left_val) = get_numlit(lit_left, &snip_left) &&
+            let Some(right_val) = get_numlit(lit_right, &snip_right) &&
+            left_val.is_decimal() && right_val.is_decimal() {
+                clippy_utils::diagnostics::span_lint_and_sugg(
+                        cx,
+                        SUSPICIOUS_XOR,
+                        expr.span,
+                        "'^' is not the exponentiation operator",
+                        "did you mean to write",
+                        format!("{}.pow({})", left_val.format(), right_val.format()),
+                        Applicability::MaybeIncorrect,
+                    );
+            }
     }
 }
 

tests/ui/suspicious_xor.rs

@@ -10,6 +10,7 @@ macro_rules! macro_test {
 
 fn main() {
     // Should warn:
+    let _ = 2 ^ 5;
     let _ = 2i32 ^ 9i32;
     let _ = 2i32 ^ 2i32;
     let _ = 50i32 ^ 3i32;

tests/ui/suspicious_xor.stderr

@@ -1,40 +1,46 @@
 error: '^' is not the exponentiation operator
   --> $DIR/suspicious_xor.rs:13:13
    |
-LL |     let _ = 2i32 ^ 9i32;
-   |             ^^^^^^^^^^^ help: did you mean to write: `2i32.pow(9)`
+LL |     let _ = 2 ^ 5;
+   |             ^^^^^ help: did you mean to write: `2.pow(5)`
    |
    = note: `-D clippy::suspicious-xor` implied by `-D warnings`
 
 error: '^' is not the exponentiation operator
   --> $DIR/suspicious_xor.rs:14:13
    |
-LL |     let _ = 2i32 ^ 2i32;
-   |             ^^^^^^^^^^^ help: did you mean to write: `2i32.pow(2)`
+LL |     let _ = 2i32 ^ 9i32;
+   |             ^^^^^^^^^^^ help: did you mean to write: `2_i32.pow(9_i32)`
 
 error: '^' is not the exponentiation operator
   --> $DIR/suspicious_xor.rs:15:13
    |
-LL |     let _ = 50i32 ^ 3i32;
-   |             ^^^^^^^^^^^^ help: did you mean to write: `50i32.pow(3)`
+LL |     let _ = 2i32 ^ 2i32;
+   |             ^^^^^^^^^^^ help: did you mean to write: `2_i32.pow(2_i32)`
 
 error: '^' is not the exponentiation operator
   --> $DIR/suspicious_xor.rs:16:13
    |
-LL |     let _ = 5i32 ^ 8i32;
-   |             ^^^^^^^^^^^ help: did you mean to write: `5i32.pow(8)`
+LL |     let _ = 50i32 ^ 3i32;
+   |             ^^^^^^^^^^^^ help: did you mean to write: `50_i32.pow(3_i32)`
 
-error: it appears that you are trying to get the maximum value of an integer, but '^' is not exponentiation operator
+error: '^' is not the exponentiation operator
   --> $DIR/suspicious_xor.rs:17:13
    |
-LL |     let _ = 2i32 ^ 32i32;
-   |             ^^^^^^^^^^^^ help: try with: `u32::MAX`
+LL |     let _ = 5i32 ^ 8i32;
+   |             ^^^^^^^^^^^ help: did you mean to write: `5_i32.pow(8_i32)`
 
 error: '^' is not the exponentiation operator
   --> $DIR/suspicious_xor.rs:18:13
    |
+LL |     let _ = 2i32 ^ 32i32;
+   |             ^^^^^^^^^^^^ help: did you mean to write: `2_i32.pow(32_i32)`
+
+error: '^' is not the exponentiation operator
+  --> $DIR/suspicious_xor.rs:19:13
+   |
 LL |     let _ = 2i32 ^ macro_test!();
-   |             ^^^^^^^^^^^^^^^^^^^^ help: did you mean to write: `2.pow(13)`
+   |             ^^^^^^^^^^^^^^^^^^^^ help: did you mean to write: `2_i32.pow(13)`
 
-error: aborting due to 6 previous errors
+error: aborting due to 7 previous errors