[pylint] Ignore identical members (PLR1714) (#22220)

## Summary

This PR closes #21692. `PLR1714` will no longer flag if all members are
identical. I iterate through the equality comparisons and if they are
all equal the rule does not flag.

## Test Plan

Additional tests were added with identical members.

crates/ruff_linter/resources/test/fixtures/pylint/repeated_equality_comparison.py

@@ -73,3 +73,7 @@ foo == 1 or foo == 1.0 # Different types, same hashed value
 foo == False or foo == 0 # Different types, same hashed value
 
 foo == 0.0 or foo == 0j # Different types, same hashed value
+
+foo == "bar" or foo == "bar" # All members identical
+
+foo == "bar" or foo == "bar" or foo == "buzz" # All but one members identical

crates/ruff_linter/src/rules/pylint/rules/repeated_equality_comparison.rs

@@ -140,6 +140,18 @@ pub(crate) fn repeated_equality_comparison(checker: &Checker, bool_op: &ast::Exp
                 continue;
             }
 
+            if let Some((&first, rest)) = comparators.split_first() {
+                let first_comparable = ComparableExpr::from(first);
+
+                if rest
+                    .iter()
+                    .all(|&c| ComparableExpr::from(c) == first_comparable)
+                {
+                    // Do not flag if all members are identical
+                    continue;
+                }
+            }
+
             // if we can determine that all the values are hashable, we can use a set
             // TODO: improve with type inference
             let all_hashable = comparators

crates/ruff_linter/src/rules/pylint/snapshots/ruff_linter__rules__pylint__tests__PLR1714_repeated_equality_comparison.py.snap

@@ -436,6 +436,7 @@ help: Merge multiple comparisons
 73 + foo in {False, 0} # Different types, same hashed value
 74 | 
 75 | foo == 0.0 or foo == 0j # Different types, same hashed value
+76 | 
 note: This is an unsafe fix and may change runtime behavior
 
 PLR1714 [*] Consider merging multiple comparisons: `foo in {0.0, 0j}`.
@@ -445,6 +446,8 @@ PLR1714 [*] Consider merging multiple comparisons: `foo in {0.0, 0j}`.
 74 |
 75 | foo == 0.0 or foo == 0j # Different types, same hashed value
    | ^^^^^^^^^^^^^^^^^^^^^^^
+76 |
+77 | foo == "bar" or foo == "bar" # All members identical
    |
 help: Merge multiple comparisons
 72 | 
@@ -452,4 +455,23 @@ help: Merge multiple comparisons
 74 | 
    - foo == 0.0 or foo == 0j # Different types, same hashed value
 75 + foo in {0.0, 0j} # Different types, same hashed value
+76 | 
+77 | foo == "bar" or foo == "bar" # All members identical
+78 | 
+note: This is an unsafe fix and may change runtime behavior
+
+PLR1714 [*] Consider merging multiple comparisons: `foo in {"bar", "bar", "buzz"}`.
+  --> repeated_equality_comparison.py:79:1
+   |
+77 | foo == "bar" or foo == "bar" # All members identical
+78 |
+79 | foo == "bar" or foo == "bar" or foo == "buzz" # All but one members identical
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: Merge multiple comparisons
+76 | 
+77 | foo == "bar" or foo == "bar" # All members identical
+78 | 
+   - foo == "bar" or foo == "bar" or foo == "buzz" # All but one members identical
+79 + foo in {"bar", "bar", "buzz"} # All but one members identical
 note: This is an unsafe fix and may change runtime behavior