From 64c38a80601a6558e38aa6f1cff1dd0ec529ab51 Mon Sep 17 00:00:00 2001
From: Sutou Kouhei <kou@clear-code.com>
Date: Fri, 6 Oct 2023 12:22:32 +0900
Subject: [PATCH] GH-38063: [C++] Use absolute path for external project's
 ar/ranlib

---
 cpp/cmake_modules/ThirdpartyToolchain.cmake | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/cpp/cmake_modules/ThirdpartyToolchain.cmake b/cpp/cmake_modules/ThirdpartyToolchain.cmake
index 6d6a2bf7751ee..e2a75ffddbfa2 100644
--- a/cpp/cmake_modules/ThirdpartyToolchain.cmake
+++ b/cpp/cmake_modules/ThirdpartyToolchain.cmake
@@ -921,11 +921,15 @@ set(EP_COMMON_TOOLCHAIN "-DCMAKE_C_COMPILER=${EP_C_COMPILER}"
                         "-DCMAKE_CXX_COMPILER=${EP_CXX_COMPILER}")
 
 if(CMAKE_AR)
-  list(APPEND EP_COMMON_TOOLCHAIN -DCMAKE_AR=${CMAKE_AR})
+  # Ensure using absolute path.
+  find_program(EP_CMAKE_AR ${CMAKE_AR} REQUIRED)
+  list(APPEND EP_COMMON_TOOLCHAIN -DCMAKE_AR=${EP_CMAKE_AR})
 endif()
 
 if(CMAKE_RANLIB)
-  list(APPEND EP_COMMON_TOOLCHAIN -DCMAKE_RANLIB=${CMAKE_RANLIB})
+  # Ensure using absolute path.
+  find_program(EP_CMAKE_RANLIB ${CMAKE_RANLIB} REQUIRED)
+  list(APPEND EP_COMMON_TOOLCHAIN -DCMAKE_RANLIB=${EP_CMAKE_RANLIB})
 endif()
 
 # External projects are still able to override the following declarations.