From 147b8b376345315b1c44939a6573bc53b9666883 Mon Sep 17 00:00:00 2001
From: Sven Klemm <sven@tigerdata.com>
Date: Fri, 31 Jul 2026 21:24:51 +0200
Subject: [PATCH] Set CCACHE_BASEDIR when using ccache

Set CCACHE_BASEDIR to the source root so ccache rewrites absolute paths
to be relative. This lets different checkouts/worktrees of the same commit
share cache entries.
---
 CMakeLists.txt | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index af1773cbd0a..5a074a6e5cf 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -129,7 +129,9 @@ if((NOT DEFINED CMAKE_C_COMPILER) AND (NOT DEFINED ENV{CC}))
         STATUS
           "Using ${PG_CCACHE_FOUND} as C compiler launcher based on pg_config CC"
       )
-      set(CMAKE_C_COMPILER_LAUNCHER ${PG_CCACHE_FOUND})
+      set(CMAKE_C_COMPILER_LAUNCHER
+          ${CMAKE_COMMAND} -E env CCACHE_BASEDIR=${CMAKE_SOURCE_DIR}
+          ${PG_CCACHE_FOUND})
     endif()
     set(PG_CC ${PG_CC_LIST})
   else()