Fixed reduction of & in cast_possible_truncation

Fixed formatting Added tests for issue rust-lang#12721 Checking for reduction on RHS
MATSMACKE · Apr 28, 2024 · fa500ff · fa500ff
1 parent 11e4934
commit fa500ff
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Showing 3 changed files with 45 additions and 2 deletions.
diff --git a/clippy_lints/src/casts/cast_possible_truncation.rs b/clippy_lints/src/casts/cast_possible_truncation.rs
@@ -46,6 +46,7 @@ fn apply_reductions(cx: &LateContext<'_>, nbits: u64, expr: &Expr<'_>, signed: b
             BinOpKind::BitAnd => get_constant_bits(cx, right)
                 .unwrap_or(u64::MAX)
                 .min(get_constant_bits(cx, left).unwrap_or(u64::MAX))
+                .min(apply_reductions(cx, nbits, right, signed))
                 .min(apply_reductions(cx, nbits, left, signed)),
             BinOpKind::Shr => apply_reductions(cx, nbits, left, signed)
                 .saturating_sub(constant_int(cx, right).map_or(0, |s| u64::try_from(s).unwrap_or_default())),

diff --git a/tests/ui/cast.rs b/tests/ui/cast.rs
@@ -15,6 +15,8 @@
     clippy::unnecessary_operation,
     clippy::unnecessary_literal_unwrap,
     clippy::identity_op
+    clippy::unnecessary_literal_unwrap,
+    clippy::identity_op
 )]
 
 fn main() {
@@ -482,8 +484,17 @@ fn issue12506() -> usize {
 }
 
 fn issue12721() {
+    fn x() -> u64 {
+        u64::MAX
+    }
+
     // Don't lint.
     (255 & 999999u64) as u8;
+    // Don't lint.
+    let _ = ((x() & 255) & 999999) as u8;
+    // Don't lint.
+    let _ = (999999 & (x() & 255)) as u8;
+
     (256 & 999999u64) as u8;
     //~^ ERROR: casting `u64` to `u8` may truncate the value
     (255 % 999999u64) as u8;

diff --git a/tests/ui/cast.stderr b/tests/ui/cast.stderr
@@ -1,4 +1,5 @@
 error: casting `i32` to `f32` causes a loss of precision (`i32` is 32 bits wide, but `f32`'s mantissa is only 23 bits wide)
+  --> tests/ui/cast.rs:23:5
   --> tests/ui/cast.rs:23:5
    |
 LL |     x0 as f32;
@@ -8,18 +9,21 @@ LL |     x0 as f32;
    = help: to override `-D warnings` add `#[allow(clippy::cast_precision_loss)]`
 
 error: casting `i64` to `f32` causes a loss of precision (`i64` is 64 bits wide, but `f32`'s mantissa is only 23 bits wide)
+  --> tests/ui/cast.rs:27:5
   --> tests/ui/cast.rs:27:5
    |
 LL |     x1 as f32;
    |     ^^^^^^^^^
 
 error: casting `i64` to `f64` causes a loss of precision (`i64` is 64 bits wide, but `f64`'s mantissa is only 52 bits wide)
+  --> tests/ui/cast.rs:29:5
   --> tests/ui/cast.rs:29:5
    |
 LL |     x1 as f64;
    |     ^^^^^^^^^
 
 error: casting `u32` to `f32` causes a loss of precision (`u32` is 32 bits wide, but `f32`'s mantissa is only 23 bits wide)
+  --> tests/ui/cast.rs:32:5
   --> tests/ui/cast.rs:32:5
    |
 LL |     x2 as f32;
@@ -32,12 +36,14 @@ LL |     x3 as f32;
    |     ^^^^^^^^^
 
 error: casting `u64` to `f64` causes a loss of precision (`u64` is 64 bits wide, but `f64`'s mantissa is only 52 bits wide)
+  --> tests/ui/cast.rs:37:5
   --> tests/ui/cast.rs:37:5
    |
 LL |     x3 as f64;
    |     ^^^^^^^^^
 
 error: casting `f32` to `i32` may truncate the value
+  --> tests/ui/cast.rs:40:5
   --> tests/ui/cast.rs:40:5
    |
 LL |     1f32 as i32;
@@ -48,6 +54,7 @@ LL |     1f32 as i32;
    = help: to override `-D warnings` add `#[allow(clippy::cast_possible_truncation)]`
 
 error: casting `f32` to `u32` may truncate the value
+  --> tests/ui/cast.rs:42:5
   --> tests/ui/cast.rs:42:5
    |
 LL |     1f32 as u32;
@@ -56,6 +63,7 @@ LL |     1f32 as u32;
    = help: if this is intentional allow the lint with `#[allow(clippy::cast_possible_truncation)]` ...
 
 error: casting `f32` to `u32` may lose the sign of the value
+  --> tests/ui/cast.rs:42:5
   --> tests/ui/cast.rs:42:5
    |
 LL |     1f32 as u32;
@@ -65,6 +73,7 @@ LL |     1f32 as u32;
    = help: to override `-D warnings` add `#[allow(clippy::cast_sign_loss)]`
 
 error: casting `f64` to `f32` may truncate the value
+  --> tests/ui/cast.rs:46:5
   --> tests/ui/cast.rs:46:5
    |
 LL |     1f64 as f32;
@@ -73,6 +82,7 @@ LL |     1f64 as f32;
    = help: if this is intentional allow the lint with `#[allow(clippy::cast_possible_truncation)]` ...
 
 error: casting `i32` to `i8` may truncate the value
+  --> tests/ui/cast.rs:48:5
   --> tests/ui/cast.rs:48:5
    |
 LL |     1i32 as i8;
@@ -85,6 +95,7 @@ LL |     i8::try_from(1i32);
    |     ~~~~~~~~~~~~~~~~~~
 
 error: casting `i32` to `u8` may truncate the value
+  --> tests/ui/cast.rs:50:5
   --> tests/ui/cast.rs:50:5
    |
 LL |     1i32 as u8;
@@ -97,6 +108,7 @@ LL |     u8::try_from(1i32);
    |     ~~~~~~~~~~~~~~~~~~
 
 error: casting `f64` to `isize` may truncate the value
+  --> tests/ui/cast.rs:52:5
   --> tests/ui/cast.rs:52:5
    |
 LL |     1f64 as isize;
@@ -105,6 +117,7 @@ LL |     1f64 as isize;
    = help: if this is intentional allow the lint with `#[allow(clippy::cast_possible_truncation)]` ...
 
 error: casting `f64` to `usize` may truncate the value
+  --> tests/ui/cast.rs:54:5
   --> tests/ui/cast.rs:54:5
    |
 LL |     1f64 as usize;
@@ -113,12 +126,14 @@ LL |     1f64 as usize;
    = help: if this is intentional allow the lint with `#[allow(clippy::cast_possible_truncation)]` ...
 
 error: casting `f64` to `usize` may lose the sign of the value
+  --> tests/ui/cast.rs:54:5
   --> tests/ui/cast.rs:54:5
    |
 LL |     1f64 as usize;
    |     ^^^^^^^^^^^^^
 
 error: casting `u32` to `u16` may truncate the value
+  --> tests/ui/cast.rs:57:5
   --> tests/ui/cast.rs:57:5
    |
 LL |     1f32 as u32 as u16;
@@ -131,6 +146,7 @@ LL |     u16::try_from(1f32 as u32);
    |     ~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 error: casting `f32` to `u32` may truncate the value
+  --> tests/ui/cast.rs:57:5
   --> tests/ui/cast.rs:57:5
    |
 LL |     1f32 as u32 as u16;
@@ -139,12 +155,14 @@ LL |     1f32 as u32 as u16;
    = help: if this is intentional allow the lint with `#[allow(clippy::cast_possible_truncation)]` ...
 
 error: casting `f32` to `u32` may lose the sign of the value
+  --> tests/ui/cast.rs:57:5
   --> tests/ui/cast.rs:57:5
    |
 LL |     1f32 as u32 as u16;
    |     ^^^^^^^^^^^
 
 error: casting `i32` to `i8` may truncate the value
+  --> tests/ui/cast.rs:62:22
   --> tests/ui/cast.rs:62:22
    |
 LL |         let _x: i8 = 1i32 as _;
@@ -157,6 +175,7 @@ LL |         let _x: i8 = 1i32.try_into();
    |                      ~~~~~~~~~~~~~~~
 
 error: casting `f32` to `i32` may truncate the value
+  --> tests/ui/cast.rs:64:9
   --> tests/ui/cast.rs:64:9
    |
 LL |         1f32 as i32;
@@ -165,6 +184,7 @@ LL |         1f32 as i32;
    = help: if this is intentional allow the lint with `#[allow(clippy::cast_possible_truncation)]` ...
 
 error: casting `f64` to `i32` may truncate the value
+  --> tests/ui/cast.rs:66:9
   --> tests/ui/cast.rs:66:9
    |
 LL |         1f64 as i32;
@@ -173,6 +193,7 @@ LL |         1f64 as i32;
    = help: if this is intentional allow the lint with `#[allow(clippy::cast_possible_truncation)]` ...
 
 error: casting `f32` to `u8` may truncate the value
+  --> tests/ui/cast.rs:68:9
   --> tests/ui/cast.rs:68:9
    |
 LL |         1f32 as u8;
@@ -181,12 +202,14 @@ LL |         1f32 as u8;
    = help: if this is intentional allow the lint with `#[allow(clippy::cast_possible_truncation)]` ...
 
 error: casting `f32` to `u8` may lose the sign of the value
+  --> tests/ui/cast.rs:68:9
   --> tests/ui/cast.rs:68:9
    |
 LL |         1f32 as u8;
    |         ^^^^^^^^^^
 
 error: casting `u8` to `i8` may wrap around the value
+  --> tests/ui/cast.rs:73:5
   --> tests/ui/cast.rs:73:5
    |
 LL |     1u8 as i8;
@@ -196,30 +219,35 @@ LL |     1u8 as i8;
    = help: to override `-D warnings` add `#[allow(clippy::cast_possible_wrap)]`
 
 error: casting `u16` to `i16` may wrap around the value
+  --> tests/ui/cast.rs:76:5
   --> tests/ui/cast.rs:76:5
    |
 LL |     1u16 as i16;
    |     ^^^^^^^^^^^
 
 error: casting `u32` to `i32` may wrap around the value
+  --> tests/ui/cast.rs:78:5
   --> tests/ui/cast.rs:78:5
    |
 LL |     1u32 as i32;
    |     ^^^^^^^^^^^
 
 error: casting `u64` to `i64` may wrap around the value
+  --> tests/ui/cast.rs:80:5
   --> tests/ui/cast.rs:80:5
    |
 LL |     1u64 as i64;
    |     ^^^^^^^^^^^
 
 error: casting `usize` to `isize` may wrap around the value
+  --> tests/ui/cast.rs:82:5
   --> tests/ui/cast.rs:82:5
    |
 LL |     1usize as isize;
    |     ^^^^^^^^^^^^^^^
 
 error: casting `usize` to `i8` may truncate the value
+  --> tests/ui/cast.rs:85:5
   --> tests/ui/cast.rs:85:5
    |
 LL |     1usize as i8;
@@ -232,6 +260,7 @@ LL |     i8::try_from(1usize);
    |     ~~~~~~~~~~~~~~~~~~~~
 
 error: casting `usize` to `i16` may truncate the value
+  --> tests/ui/cast.rs:88:5
   --> tests/ui/cast.rs:88:5
    |
 LL |     1usize as i16;
@@ -244,6 +273,7 @@ LL |     i16::try_from(1usize);
    |     ~~~~~~~~~~~~~~~~~~~~~
 
 error: casting `usize` to `i16` may wrap around the value on targets with 16-bit wide pointers
+  --> tests/ui/cast.rs:88:5
   --> tests/ui/cast.rs:88:5
    |
 LL |     1usize as i16;
@@ -253,6 +283,7 @@ LL |     1usize as i16;
    = note: for more information see https://doc.rust-lang.org/reference/types/numeric.html#machine-dependent-integer-types
 
 error: casting `usize` to `i32` may truncate the value on targets with 64-bit wide pointers
+  --> tests/ui/cast.rs:93:5
   --> tests/ui/cast.rs:93:5
    |
 LL |     1usize as i32;
@@ -708,7 +739,7 @@ LL |     bar.unwrap().unwrap() as usize
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: casting `u64` to `u8` may truncate the value
-  --> tests/ui/cast.rs:487:5
+  --> tests/ui/cast.rs:496:5
    |
 LL |     (256 & 999999u64) as u8;
    |     ^^^^^^^^^^^^^^^^^^^^^^^
@@ -720,7 +751,7 @@ LL |     u8::try_from(256 & 999999u64);
    |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 error: casting `u64` to `u8` may truncate the value
-  --> tests/ui/cast.rs:489:5
+  --> tests/ui/cast.rs:498:5
    |
 LL |     (255 % 999999u64) as u8;
    |     ^^^^^^^^^^^^^^^^^^^^^^^