[clang] [clang-format] Handle Trailing Whitespace After Line Continuation (P2223R2) (PR #145243)

[Owen Pan via cfe-commits]

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@@ -25768,6 +25768,29 @@ TEST_F(FormatTest, OperatorPassedAsAFunctionPtr) {
   verifyFormat("foo(operator, , -42);", Style);
 }
 
+TEST_F(FormatTest, LineSpliceWithTrailingWhitespace) {
+  // Test that each sequence of a backslash (\) immediately followed by zero or
+  // more horizontal whitespace characters and then a new-line character is
+  // treated as a single logical line while formatting (as per P2223R2).
+  FormatStyle Style = getLLVMStyle();
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owenca wrote:

```suggestion
  auto Style = getLLVMStyle();
```

https://github.com/llvm/llvm-project/pull/145243