From 22cd66a286d52578de9ed9e052ba5f8b60ebdce1 Mon Sep 17 00:00:00 2001
From: Giulio Eulisse <10544+ktf@users.noreply.github.com>
Date: Mon, 5 Oct 2026 20:16:16 +0200
Subject: [PATCH] Prevent broken tests related statements when BUILD_TESTING is
 OFF

---
 DataFormats/Detectors/Common/CMakeLists.txt |  2 +-
 Utilities/rANS/CMakeLists.txt               |  4 ++++
 cmake/O2AddTest.cmake                       | 14 ++++++++++----
 3 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/DataFormats/Detectors/Common/CMakeLists.txt b/DataFormats/Detectors/Common/CMakeLists.txt
index bbc0aaf9e8320..e96126c6adf7e 100644
--- a/DataFormats/Detectors/Common/CMakeLists.txt
+++ b/DataFormats/Detectors/Common/CMakeLists.txt
@@ -60,6 +60,6 @@ o2_add_test(CTFEntropyCoder
             COMPONENT_NAME DetectorsCommonDataFormats
             TARGETVARNAME TEST_CTF_ENTROPY_CODER
             LABELS detectorsbase)
-if(CMAKE_HOST_SYSTEM_PROCESSOR STREQUAL "x86_64")
+if(BUILD_TESTING AND CMAKE_HOST_SYSTEM_PROCESSOR STREQUAL "x86_64")
         target_compile_options(${TEST_CTF_ENTROPY_CODER} PRIVATE -march=native)
 endif()
diff --git a/Utilities/rANS/CMakeLists.txt b/Utilities/rANS/CMakeLists.txt
index 710fe7879571c..d140fa0ef7d3f 100644
--- a/Utilities/rANS/CMakeLists.txt
+++ b/Utilities/rANS/CMakeLists.txt
@@ -51,6 +51,9 @@ if(${ENABLE_VTUNE_PROFILER})
   target_link_libraries(${LIBRANS} INTERFACE PkgConfig::Vtune)
 endif()
 
+# o2_add_test() returns early when BUILD_TESTING is off, so TARGETVARNAME is
+# never set and the target_compile_options() below would see an empty target.
+if(BUILD_TESTING)
 o2_add_test(Utils
             NAME ransUtils
             SOURCES test/test_ransUtils.cxx
@@ -186,6 +189,7 @@ o2_add_test(Serialize
             TARGETVARNAME TEST_SERIALIZE
             LABELS utils)
             target_compile_options(${TEST_SERIALIZE} PRIVATE ${RANS_TEST_ARCH})
+endif()
 
 if (TARGET benchmark::benchmark)
     o2_add_header_only_library(libransBenchmark
diff --git a/cmake/O2AddTest.cmake b/cmake/O2AddTest.cmake
index 5687b01724106..b896074cc618e 100644
--- a/cmake/O2AddTest.cmake
+++ b/cmake/O2AddTest.cmake
@@ -63,10 +63,6 @@ include(O2AddExecutable)
 
 function(o2_add_test)
 
-  if(NOT BUILD_TESTING)
-    return()
-  endif()
-
   cmake_parse_arguments(
     PARSE_ARGV
     1
@@ -80,6 +76,16 @@ function(o2_add_test)
     message(FATAL_ERROR "Unexpected unparsed arguments: ${A_UNPARSED_ARGUMENTS}")
   endif()
 
+  # Parsed before this check so TARGETVARNAME can be defined (empty) even when
+  # no target is made: `if(VAR)` at the call site is then reliable, and a value
+  # left by an earlier call cannot leak into it.
+  if(NOT BUILD_TESTING)
+    if(A_TARGETVARNAME)
+      set(${A_TARGETVARNAME} "" PARENT_SCOPE)
+    endif()
+    return()
+  endif()
+
   set(testName ${ARGV0})
 
   set(linkLibraries ${A_PUBLIC_LINK_LIBRARIES})