Help: Document CMAKE_UNITY_BUILD/CMAKE_EXPORT_COMPILE_COMMANDS limitation
These two options currently do not work well together. Mention this
limitation in the documentation.
Issue: #19826
diff --git a/Help/prop_tgt/UNITY_BUILD.rst b/Help/prop_tgt/UNITY_BUILD.rst
index 1e68dcd..2faad92 100644
--- a/Help/prop_tgt/UNITY_BUILD.rst
+++ b/Help/prop_tgt/UNITY_BUILD.rst
@@ -26,6 +26,12 @@
which will ``#include`` the source files, and exclude them from
building by setting :prop_sf:`HEADER_FILE_ONLY` to ``ON``.
+.. note::
+
+ Marking the original sources with :prop_sf:`HEADER_FILE_ONLY`
+ is considered an implementation detail that may change in the
+ future because it does not work well in combination with
+ the :variable:`CMAKE_EXPORT_COMPILE_COMMANDS` variable.
ODR (One definition rule) errors
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/Help/variable/CMAKE_EXPORT_COMPILE_COMMANDS.rst b/Help/variable/CMAKE_EXPORT_COMPILE_COMMANDS.rst
index 8776279..4548abc 100644
--- a/Help/variable/CMAKE_EXPORT_COMPILE_COMMANDS.rst
+++ b/Help/variable/CMAKE_EXPORT_COMPILE_COMMANDS.rst
@@ -28,3 +28,7 @@
.. note::
This option is implemented only by :ref:`Makefile Generators`
and the :generator:`Ninja`. It is ignored on other generators.
+
+ This option currently does not work well in combination with
+ the :prop_tgt:`UNITY_BUILD` target property or the
+ :variable:`CMAKE_UNITY_BUILD` variable.
diff --git a/Help/variable/CMAKE_UNITY_BUILD.rst b/Help/variable/CMAKE_UNITY_BUILD.rst
index b653881..bbcfd68 100644
--- a/Help/variable/CMAKE_UNITY_BUILD.rst
+++ b/Help/variable/CMAKE_UNITY_BUILD.rst
@@ -6,3 +6,7 @@
sources within each target. This feature is known as "Unity build",
or "Jumbo build". By default this variable is not set and so does
not enable unity builds on targets.
+
+.. note::
+ This option currently does not work well in combination with
+ the :variable:`CMAKE_EXPORT_COMPILE_COMMANDS` variable.
