[llvm] [Windows][test] Fix "LLVM" test failures when LLVM_WINDOWS_PREFER_FORWARD_SLASH is ON (PR #184556)

[Junji Watanabe via llvm-commits]

https://github.com/Jwata updated https://github.com/llvm/llvm-project/pull/184556

>From a91749199b3c63cca5b4d792d7c55ce8ddf0b245 Mon Sep 17 00:00:00 2001
From: Junji Watanabe <jwata at google.com>
Date: Wed, 4 Mar 2026 13:22:33 +0900
Subject: [PATCH] fix llvm tests

---
 llvm/test/tools/llvm-cov/directory_coverage.win.test      | 8 ++++----
 llvm/test/tools/llvm-cov/native_separators.c              | 6 +++---
 .../X86/source-interleave-prefix-windows.test             | 2 +-
 llvm/unittests/Support/CommandLineTest.cpp                | 4 ++--
 llvm/unittests/Support/Path.cpp                           | 7 ++++++-
 5 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/llvm/test/tools/llvm-cov/directory_coverage.win.test b/llvm/test/tools/llvm-cov/directory_coverage.win.test
index f948bdcae3a58..739375a037f48 100644
--- a/llvm/test/tools/llvm-cov/directory_coverage.win.test
+++ b/llvm/test/tools/llvm-cov/directory_coverage.win.test
@@ -23,13 +23,13 @@
 
 
 
-# HTML-TOP: coverage\index.html
+# HTML-TOP: coverage{{[/\\]}}index.html
 
-# ROOT: a0\a1\a2.cc
-# ROOT: b0\
+# ROOT: a0{{[/\\]}}a1{{[/\\]}}a2.cc
+# ROOT: b0{{[/\\]}}
 # ROOT-NOT: b1_1.cc
 # ROOT-NOT: b1_2.cc
-# ROOT: c0\c1\
+# ROOT: c0{{[/\\]}}c1{{[/\\]}}
 # ROOT-NOT: c2_1.cc
 # ROOT-NOT: b2_2.cc
 # ROOT: main.cc
diff --git a/llvm/test/tools/llvm-cov/native_separators.c b/llvm/test/tools/llvm-cov/native_separators.c
index 3c768e1014b92..b6ad175aa8f33 100644
--- a/llvm/test/tools/llvm-cov/native_separators.c
+++ b/llvm/test/tools/llvm-cov/native_separators.c
@@ -13,8 +13,8 @@
 // RUN: llvm-cov show -format=html %S/Inputs/native_separators.covmapping -instr-profile=%t.profdata -path-equivalence=/tmp,%S %s -o %t.dir
 // RUN: FileCheck -check-prefixes=HTML -input-file=%t.dir/coverage/tmp/native_separators.c.html %s
 
-// TEXT-INDEX: \tmp\native_separators.c
-// HTML-INDEX: >tmp\native_separators.c</a>
-// HTML: <pre>\tmp\native_separators.c</pre>
+// TEXT-INDEX: {{[/\\]}}tmp{{[/\\]}}native_separators.c
+// HTML-INDEX: >tmp{{[/\\]}}native_separators.c</a>
+// HTML: <pre>{{[/\\]}}tmp{{[/\\]}}native_separators.c</pre>
 
 int main() {}
diff --git a/llvm/test/tools/llvm-objdump/X86/source-interleave-prefix-windows.test b/llvm/test/tools/llvm-objdump/X86/source-interleave-prefix-windows.test
index 0f8952daec42e..db5265b26d5a3 100644
--- a/llvm/test/tools/llvm-objdump/X86/source-interleave-prefix-windows.test
+++ b/llvm/test/tools/llvm-objdump/X86/source-interleave-prefix-windows.test
@@ -7,5 +7,5 @@
 ; RUN: sed -e "s,SRC_COMPDIR,/Inputs,g" %p/Inputs/source-interleave.ll > %t.ll
 ; RUN: llc -o %t.o -filetype=obj -mtriple=x86_64-pc-linux %t.ll
 ; RUN: llvm-objdump --prefix 'myprefix/\' --source %t.o 2>&1 | FileCheck %s -DFILE=%t.o -DPREFIX='myprefix'
-; CHECK: warning: '[[FILE]]': failed to find source [[PREFIX]]/Inputs\source-interleave-x86_64.c
+; CHECK: warning: '[[FILE]]': failed to find source [[PREFIX]]{{[/\\]}}Inputs{{[/\\]}}source-interleave-x86_64.c
 
diff --git a/llvm/unittests/Support/CommandLineTest.cpp b/llvm/unittests/Support/CommandLineTest.cpp
index 9e8a165fe136f..2f91c2ac8c1f0 100644
--- a/llvm/unittests/Support/CommandLineTest.cpp
+++ b/llvm/unittests/Support/CommandLineTest.cpp
@@ -950,7 +950,7 @@ TEST(CommandLineTest, ResponseFiles) {
 TEST(CommandLineTest, RecursiveResponseFiles) {
   vfs::InMemoryFileSystem FS;
 #ifdef _WIN32
-  const char *TestRoot = "C:\\";
+  const char *TestRoot = LLVM_WINDOWS_PREFER_FORWARD_SLASH ? "C:/" : "C:\\";
 #else
   const char *TestRoot = "/";
 #endif
@@ -1020,7 +1020,7 @@ TEST(CommandLineTest, RecursiveResponseFiles) {
 TEST(CommandLineTest, ResponseFilesAtArguments) {
   vfs::InMemoryFileSystem FS;
 #ifdef _WIN32
-  const char *TestRoot = "C:\\";
+  const char *TestRoot = LLVM_WINDOWS_PREFER_FORWARD_SLASH ? "C:/" : "C:\\";
 #else
   const char *TestRoot = "/";
 #endif
diff --git a/llvm/unittests/Support/Path.cpp b/llvm/unittests/Support/Path.cpp
index b27ed6f950b10..984e99024c484 100644
--- a/llvm/unittests/Support/Path.cpp
+++ b/llvm/unittests/Support/Path.cpp
@@ -11,6 +11,7 @@
 #include "llvm/ADT/ScopeExit.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/BinaryFormat/Magic.h"
+#include "llvm/Config/config.h"
 #include "llvm/Config/llvm-config.h" // for LLVM_ON_UNIX
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/ConvertUTF.h"
@@ -2584,7 +2585,9 @@ TEST_F(FileSystemTest, makeLongFormPath) {
 
   // Setup: A test directory longer than 8 characters for which a distinct
   // short 8.3 form name will be created on Windows. Typically, 123456~1.
-  constexpr const char *OneDir = "\\123456789"; // >8 chars
+  const char *OneDir = LLVM_WINDOWS_PREFER_FORWARD_SLASH
+                           ? "/123456789"
+                           : "\\123456789"; // >8 chars
 
   // Setup: Create a path where even if all components were reduced to short 8.3
   // form names, the total length would exceed MAX_PATH.
@@ -2617,6 +2620,8 @@ TEST_F(FileSystemTest, makeLongFormPath) {
   ASSERT_FALSE(DotAndDotDot.empty())
       << "Expected short 8.3 form path for test directory.";
   auto ContainsDotAndDotDot = [](llvm::StringRef S) {
+    if (LLVM_WINDOWS_PREFER_FORWARD_SLASH)
+      return S.contains("/./") && S.contains("/../");
     return S.contains("\\.\\") && S.contains("\\..\\");
   };
   ASSERT_TRUE(ContainsDotAndDotDot(DotAndDotDot))