From e5745e49e3005e2c2ac12edab2cd3884f0d62123 Mon Sep 17 00:00:00 2001
From: Aiden Grossman <aidengrossman@google.com>
Date: Wed, 10 Sep 2025 16:33:33 +0000
Subject: [PATCH] Reapply "[APINotes] Prefer diff -u over diff -b"

This reverts commit 8d35bcc52117b79517f518de952b4b50463de160.

This was causing failures on MacOS due to the head command there not
supporting negative offsets. This patch fixes that by removing the call
to HEAD and relaxing the requirements around removing the last line of
the file.
---
 clang/test/APINotes/yaml-roundtrip-2.test | 12 +++----
 clang/test/APINotes/yaml-roundtrip.test   | 43 ++++++++++-------------
 2 files changed, 23 insertions(+), 32 deletions(-)

diff --git a/clang/test/APINotes/yaml-roundtrip-2.test b/clang/test/APINotes/yaml-roundtrip-2.test
index 63717bda7c099..26c5a73ad1083 100644
--- a/clang/test/APINotes/yaml-roundtrip-2.test
+++ b/clang/test/APINotes/yaml-roundtrip-2.test
@@ -1,11 +1,9 @@
 RUN: apinotes-test %S/Inputs/Frameworks/SimpleKit.framework/Headers/SimpleKit.apinotes > %t.result
-RUN: not diff -b -e %t.result %S/Inputs/Frameworks/SimpleKit.framework/Headers/SimpleKit.apinotes | FileCheck %s
-
-The `-e` option of `diff` is not implemented in the builtin diff, assume
-that we have a POSIX compatible diff when we have a shell.
-REQUIRES: shell
+RUN: not diff -u %S/Inputs/Frameworks/SimpleKit.framework/Headers/SimpleKit.apinotes %t.result | \
+RUN:   tail -n +4 | \
+RUN:   FileCheck %s --implicit-check-not="{{^\+}}" --implicit-check-not="{{^\-}}"
 
 We expect only the document markers to be emitted
 
-CHECK: 52d
-CHECK: 1d
+CHECK: +---
+CHECK: +...
diff --git a/clang/test/APINotes/yaml-roundtrip.test b/clang/test/APINotes/yaml-roundtrip.test
index f69038ca828b1..355596ef8e93b 100644
--- a/clang/test/APINotes/yaml-roundtrip.test
+++ b/clang/test/APINotes/yaml-roundtrip.test
@@ -1,30 +1,23 @@
 RUN: apinotes-test %S/Inputs/Frameworks/Simple.framework/Headers/Simple.apinotes > %t.result
-RUN: not diff -b %S/Inputs/Frameworks/Simple.framework/Headers/Simple.apinotes %t.result | FileCheck %s
-
-Avoid Windows as the diff output differs due to line-endings and different diff
-implementations.
-UNSUPPORTED: system-windows
+RUN: not diff -u %S/Inputs/Frameworks/Simple.framework/Headers/Simple.apinotes %t.result | \
+RUN:   tail -n +5 | \
+RUN:   FileCheck %s --implicit-check-not="{{^\+}}" --implicit-check-not="{{^\-}}"
 
 We expect only the nullability to be different as it is canonicalized during the
 roudtrip.
 
-CHECK:      7c8
-CHECK-NEXT: <         Nullability:     N
-CHECK-NEXT: ---
-CHECK-NEXT: >         Nullability:     Nonnull
-CHECK-NEXT: 13c14
-CHECK-NEXT: <         Nullability:     O
-CHECK-NEXT: ---
-CHECK-NEXT: >         Nullability:     Optional
-CHECK-NEXT: 19c20
-CHECK-NEXT: <         Nullability:     U
-CHECK-NEXT: ---
-CHECK-NEXT: >         Nullability:     Unspecified
-CHECK-NEXT: 25c26
-CHECK-NEXT: <         Nullability:     S
-CHECK-NEXT: ---
-CHECK-NEXT: >         Nullability:     Unspecified
-CHECK-NEXT: 28c29
-CHECK-NEXT: <         Nullability:     Scalar
-CHECK-NEXT: ---
-CHECK-NEXT: >         Nullability:     Unspecified
+CHECK:      -        Nullability:     N
+CHECK-NEXT: +        Nullability:     Nonnull
+CHECK:      -        Nullability:     O
+CHECK-NEXT: +        Nullability:     Optional
+CHECK:      -        Nullability:     U
+CHECK-NEXT: +        Nullability:     Unspecified
+CHECK:      -        Nullability:     S
+CHECK-NEXT: +        Nullability:     Unspecified
+CHECK:      -        Nullability:     Scalar
+CHECK-NEXT: +        Nullability:     Unspecified
+
+# The roundtrip will add document markers. It is hard to remove the last line of the
+# file in a cross-platform manner, so just assert it here to avoid a test failure due
+# to the implicit check not.
+# CHECK: +