From fa65a228f4b46346e69e9b95805a8bcfa8483a60 Mon Sep 17 00:00:00 2001
From: Aiden Grossman <aidengrossman@google.com>
Date: Sat, 26 Apr 2025 04:51:16 +0000
Subject: [PATCH] Revert "[CMake] Do not set CMP0116 explicitly to old
 (#90385)"

This reverts commit ab405fb6e9ff9202ca722f632b945d4b84c653f5.

This caused quite a few buildbot failures that need further
investigation.
---
 cmake/Modules/CMakePolicy.cmake   |  6 ++++++
 llvm/cmake/modules/TableGen.cmake | 25 ++++++++++++-------------
 mlir/cmake/modules/AddMLIR.cmake  | 25 ++++++++++++-------------
 3 files changed, 30 insertions(+), 26 deletions(-)

diff --git a/cmake/Modules/CMakePolicy.cmake b/cmake/Modules/CMakePolicy.cmake
index 421f5a4dda6c..bafd6bb5b025 100644
--- a/cmake/Modules/CMakePolicy.cmake
+++ b/cmake/Modules/CMakePolicy.cmake
@@ -1,5 +1,11 @@
 # CMake policy settings shared between LLVM projects
 
+# CMP0116: Ninja generators transform `DEPFILE`s from `add_custom_command()`
+# New in CMake 3.20. https://cmake.org/cmake/help/latest/policy/CMP0116.html
+if(POLICY CMP0116)
+  cmake_policy(SET CMP0116 OLD)
+endif()
+
 # MSVC debug information format flags are selected via
 # CMAKE_MSVC_DEBUG_INFORMATION_FORMAT, instead of
 # embedding flags in e.g. CMAKE_CXX_FLAGS_RELEASE.
diff --git a/llvm/cmake/modules/TableGen.cmake b/llvm/cmake/modules/TableGen.cmake
index dfe002fde43f..bf914c379e80 100644
--- a/llvm/cmake/modules/TableGen.cmake
+++ b/llvm/cmake/modules/TableGen.cmake
@@ -21,21 +21,20 @@ function(tablegen project ofn)
     message(FATAL_ERROR "${project}_TABLEGEN_EXE not set")
   endif()
 
-  # Use depfile instead of globbing arbitrary *.td(s) for Ninja. We force
-  # CMake versions older than v3.30 on Windows to use the fallback behavior
-  # due to a depfile parsing bug on Windows paths in versions prior to 3.30.
-  # https://gitlab.kitware.com/cmake/cmake/-/issues/25943
-  cmake_policy(GET CMP0116 cmp0116_state)
-  if(CMAKE_GENERATOR MATCHES "Ninja" AND cmp0116_state STREQUAL NEW
-     AND NOT (CMAKE_HOST_WIN32 AND CMAKE_VERSION VERSION_LESS 3.30))
+  # Use depfile instead of globbing arbitrary *.td(s) for Ninja.
+  if(CMAKE_GENERATOR MATCHES "Ninja")
+    # Make output path relative to build.ninja, assuming located on
+    # ${CMAKE_BINARY_DIR}.
     # CMake emits build targets as relative paths but Ninja doesn't identify
-    # absolute path (in *.d) as relative path (in build.ninja). Post CMP0116,
-    # CMake handles this discrepancy for us, otherwise we use the fallback
-    # logic.
+    # absolute path (in *.d) as relative path (in build.ninja)
+    # Note that tblgen is executed on ${CMAKE_BINARY_DIR} as working directory.
+    file(RELATIVE_PATH ofn_rel
+      ${CMAKE_BINARY_DIR} ${CMAKE_CURRENT_BINARY_DIR}/${ofn})
     set(additional_cmdline
-      -o ${ofn}
-      -d ${ofn}.d
-      DEPFILE ${ofn}.d
+      -o ${ofn_rel}
+      -d ${ofn_rel}.d
+      WORKING_DIRECTORY ${CMAKE_BINARY_DIR}
+      DEPFILE ${CMAKE_CURRENT_BINARY_DIR}/${ofn}.d
       )
     set(local_tds)
     set(global_tds)
diff --git a/mlir/cmake/modules/AddMLIR.cmake b/mlir/cmake/modules/AddMLIR.cmake
index e923950f9c81..2fc84a5b2879 100644
--- a/mlir/cmake/modules/AddMLIR.cmake
+++ b/mlir/cmake/modules/AddMLIR.cmake
@@ -42,21 +42,20 @@ function(_pdll_tablegen project ofn)
     message(FATAL_ERROR "${project}_TABLEGEN_EXE not set")
   endif()
 
-  # Use depfile instead of globbing arbitrary *.td(s) for Ninja. We force
-  # CMake versions older than v3.30 on Windows to use the fallback behavior
-  # due to a depfile parsing bug on Windows paths in versions prior to 3.30.
-  # https://gitlab.kitware.com/cmake/cmake/-/issues/25943
-  cmake_policy(GET CMP0116 cmp0116_state)
-  if(CMAKE_GENERATOR MATCHES "Ninja" AND cmp0116_state STREQUAL NEW
-     AND NOT (CMAKE_HOST_WIN32 AND CMAKE_VERSION VERSION_LESS 3.30))
+  # Use depfile instead of globbing arbitrary *.td(s) for Ninja.
+  if(CMAKE_GENERATOR MATCHES "Ninja")
+    # Make output path relative to build.ninja, assuming located on
+    # ${CMAKE_BINARY_DIR}.
     # CMake emits build targets as relative paths but Ninja doesn't identify
-    # absolute path (in *.d) as relative path (in build.ninja). Post CMP0116,
-    # CMake handles this discrepancy for us. Otherwise, we use the fallback
-    # logic.
+    # absolute path (in *.d) as relative path (in build.ninja)
+    # Note that tblgen is executed on ${CMAKE_BINARY_DIR} as working directory.
+    file(RELATIVE_PATH ofn_rel
+      ${CMAKE_BINARY_DIR} ${CMAKE_CURRENT_BINARY_DIR}/${ofn})
     set(additional_cmdline
-      -o ${ofn}
-      -d ${ofn}.d
-      DEPFILE ${ofn}.d
+      -o ${ofn_rel}
+      -d ${ofn_rel}.d
+      WORKING_DIRECTORY ${CMAKE_BINARY_DIR}
+      DEPFILE ${CMAKE_CURRENT_BINARY_DIR}/${ofn}.d
       )
     set(local_tds)
     set(global_tds)