Auto merge of #10353 - nindalf:master, r=llogiq

Change unusual_byte_groupings to require byte groupings of equal size

Fixes issue #6556

This lint required byte groupings of size 2 or 4 for `Radix::Binary` and `Radix::Hexadecimal`. Since there are good reasons for allowing groups of other sizes, this PR relaxes the restriction. This lint now requires that

- group sizes after the first group be of the same size and
- greater or equal in size to the first group.

---

changelog: [`unusual_byte_groupings`]: reduce false positives by relaxing restriction requiring groups of specific sizes.

clippy_lints/src/literal_representation.rs

@@ -210,7 +210,7 @@ impl WarningType {
                 cx,
                 UNUSUAL_BYTE_GROUPINGS,
                 span,
-                "digits of hex or binary literal not grouped by four",
+                "digits of hex, binary or octal literal not in groups of equal size",
                 "consider",
                 suggested_format,
                 Applicability::MachineApplicable,
@@ -427,8 +427,12 @@ impl LiteralDigitGrouping {
 
         let first = groups.next().expect("At least one group");
 
-        if (radix == Radix::Binary || radix == Radix::Hexadecimal) && groups.any(|i| i != 4 && i != 2) {
-            return Err(WarningType::UnusualByteGroupings);
+        if radix == Radix::Binary || radix == Radix::Octal || radix == Radix::Hexadecimal {
+            if let Some(second_size) = groups.next() {
+                if !groups.all(|i| i == second_size) || first > second_size {
+                    return Err(WarningType::UnusualByteGroupings);
+                }
+            }
         }
 
         if let Some(second) = groups.next() {

tests/ui/large_digit_groups.fixed

@@ -11,7 +11,7 @@ fn main() {
     let _good = (
         0b1011_i64,
         0o1_234_u32,
-        0x0123_4567,
+        0x1_234_567,
         1_2345_6789,
         1234_f32,
         1_234.12_f32,
@@ -19,7 +19,7 @@ fn main() {
         1.123_4_f32,
     );
     let _bad = (
-        0b11_0110_i64,
+        0b1_10110_i64,
         0xdead_beef_usize,
         123_456_f32,
         123_456.12_f32,

tests/ui/large_digit_groups.stderr

@@ -1,22 +1,10 @@
-error: digits of hex or binary literal not grouped by four
-  --> $DIR/large_digit_groups.rs:14:9
-   |
-LL |         0x1_234_567,
-   |         ^^^^^^^^^^^ help: consider: `0x0123_4567`
-   |
-   = note: `-D clippy::unusual-byte-groupings` implied by `-D warnings`
-
-error: digits of hex or binary literal not grouped by four
-  --> $DIR/large_digit_groups.rs:22:9
-   |
-LL |         0b1_10110_i64,
-   |         ^^^^^^^^^^^^^ help: consider: `0b11_0110_i64`
-
-error: digits of hex or binary literal not grouped by four
+error: digits of hex, binary or octal literal not in groups of equal size
   --> $DIR/large_digit_groups.rs:23:9
    |
 LL |         0xd_e_adbee_f_usize,
    |         ^^^^^^^^^^^^^^^^^^^ help: consider: `0xdead_beef_usize`
+   |
+   = note: `-D clippy::unusual-byte-groupings` implied by `-D warnings`
 
 error: digit groups should be smaller
   --> $DIR/large_digit_groups.rs:24:9
@@ -44,5 +32,5 @@ error: digit groups should be smaller
 LL |         1_23456.12345_6_f64,
    |         ^^^^^^^^^^^^^^^^^^^ help: consider: `123_456.123_456_f64`
 
-error: aborting due to 7 previous errors
+error: aborting due to 5 previous errors
 

tests/ui/literals.stderr

@@ -121,7 +121,7 @@ error: digits grouped inconsistently by underscores
 LL |     let fail23 = 3__16___23;
    |                  ^^^^^^^^^^ help: consider: `31_623`
 
-error: digits of hex or binary literal not grouped by four
+error: digits of hex, binary or octal literal not in groups of equal size
   --> $DIR/literals.rs:38:18
    |
 LL |     let fail24 = 0xAB_ABC_AB;
@@ -129,12 +129,6 @@ LL |     let fail24 = 0xAB_ABC_AB;
    |
    = note: `-D clippy::unusual-byte-groupings` implied by `-D warnings`
 
-error: digits of hex or binary literal not grouped by four
-  --> $DIR/literals.rs:39:18
-   |
-LL |     let fail25 = 0b01_100_101;
-   |                  ^^^^^^^^^^^^ help: consider: `0b0110_0101`
-
 error: this is a decimal constant
   --> $DIR/literals.rs:46:13
    |
@@ -168,5 +162,5 @@ help: if you mean to use a decimal constant, remove the `0` to avoid confusion
 LL |     let _ = 89;
    |             ~~
 
-error: aborting due to 21 previous errors
+error: aborting due to 20 previous errors
 

tests/ui/unreadable_literal.fixed

@@ -23,7 +23,7 @@ fn main() {
     let _good = (
         0b1011_i64,
         0o1_234_u32,
-        0x0123_4567,
+        0x1_234_567,
         65536,
         1_2345_6789,
         1234_f32,

tests/ui/unreadable_literal.stderr

@@ -1,11 +1,3 @@
-error: digits of hex or binary literal not grouped by four
-  --> $DIR/unreadable_literal.rs:26:9
-   |
-LL |         0x1_234_567,
-   |         ^^^^^^^^^^^ help: consider: `0x0123_4567`
-   |
-   = note: `-D clippy::unusual-byte-groupings` implied by `-D warnings`
-
 error: long literal lacking separators
   --> $DIR/unreadable_literal.rs:34:17
    |
@@ -68,5 +60,5 @@ error: long literal lacking separators
 LL |     let _fail5 = 1.100300400;
    |                  ^^^^^^^^^^^ help: consider: `1.100_300_400`
 
-error: aborting due to 11 previous errors
+error: aborting due to 10 previous errors