[clang-tools-extra] [clang-tidy] Fix clang-tidy-diff with not producing blank lines (PR #213873)

[Baranov Victor via cfe-commits]

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@@ -9,6 +9,14 @@
 
 // RUN: not diff -U0 %s %t.cpp | %clang_tidy_diff -checks=-*,modernize-use-override -j 1 -- -std=c++11 2>&1 | FileCheck %s --check-prefix=CHECK-J1
 // CHECK-J1: Running clang-tidy in 1 threads...
+
+// Test that running over multiple files don't produce blank lines in output
+// RUN: not diff -U0 %s %t.cpp > %t.diff
+// RUN: sed 's/PLACEHOLDER/a + b + 0/' %S/Inputs/clang-tidy-diff/test.cpp > %t.clean.cpp
+// RUN: not diff -U0 %S/Inputs/clang-tidy-diff/test.cpp %t.clean.cpp > %t.clean.diff
+// RUN: cat %t.clean.diff %t.diff | %clang_tidy_diff -checks=-*,modernize-use-override -j 1 -- -std=c++11 2>&1 | FileCheck %s --check-prefix=CHECK-NOBLANK
+// CHECK-NOBLANK: Running clang-tidy in 1 threads...
+// CHECK-NOBLANK-NEXT: :8: warning: annotate this
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vbvictor wrote:

The test actually failing without the fix

https://github.com/llvm/llvm-project/pull/213873