Add support for x32-abi

Detect x32-abi through CMakeCompilerABI infrastruture and use this
information at runtime to determine the correct library paths with
`FIND_LIBRARY_USE_LIBX32_PATHS`.

Fixes: #15994

4 files changed, 23 insertions, 1 deletions

diff --git a/Help/command/find_library.rst b/Help/command/find_library.rst
index e912040..f774f17 100644
--- a/Help/command/find_library.rst
+++ b/Help/command/find_library.rst
@@ -53,7 +53,8 @@ If the :variable:`CMAKE_FIND_LIBRARY_CUSTOM_LIB_SUFFIX` variable is set all
 search paths will be tested as normal, with the suffix appended, and with
 all matches of ``lib/`` replaced with
 ``lib${CMAKE_FIND_LIBRARY_CUSTOM_LIB_SUFFIX}/``.  This variable overrides
-the :prop_gbl:`FIND_LIBRARY_USE_LIB32_PATHS`
+the :prop_gbl:`FIND_LIBRARY_USE_LIB32_PATHS`,
+:prop_gbl:`FIND_LIBRARY_USE_LIBX32_PATHS`,
 and :prop_gbl:`FIND_LIBRARY_USE_LIB64_PATHS` global properties.
 
 If the :prop_gbl:`FIND_LIBRARY_USE_LIB32_PATHS` global property is set
@@ -63,6 +64,13 @@ automatically set for the platforms that are known to need it if at
 least one of the languages supported by the :command:`project` command
 is enabled.
 
+If the :prop_gbl:`FIND_LIBRARY_USE_LIBX32_PATHS` global property is set
+all search paths will be tested as normal, with ``x32/`` appended, and
+with all matches of ``lib/`` replaced with ``libx32/``.  This property is
+automatically set for the platforms that are known to need it if at
+least one of the languages supported by the :command:`project` command
+is enabled.
+
 If the :prop_gbl:`FIND_LIBRARY_USE_LIB64_PATHS` global property is set
 all search paths will be tested as normal, with ``64/`` appended, and
 with all matches of ``lib/`` replaced with ``lib64/``.  This property is
diff --git a/Help/manual/cmake-properties.7.rst b/Help/manual/cmake-properties.7.rst
index 5bd6365..2157ba5 100644
--- a/Help/manual/cmake-properties.7.rst
+++ b/Help/manual/cmake-properties.7.rst
@@ -26,6 +26,7 @@ Properties of Global Scope
    /prop_gbl/ENABLED_LANGUAGES
    /prop_gbl/FIND_LIBRARY_USE_LIB32_PATHS
    /prop_gbl/FIND_LIBRARY_USE_LIB64_PATHS
+   /prop_gbl/FIND_LIBRARY_USE_LIBX32_PATHS
    /prop_gbl/FIND_LIBRARY_USE_OPENBSD_VERSIONING
    /prop_gbl/GLOBAL_DEPENDS_DEBUG_MODE
    /prop_gbl/GLOBAL_DEPENDS_NO_CYCLES
diff --git a/Help/prop_gbl/FIND_LIBRARY_USE_LIBX32_PATHS.rst b/Help/prop_gbl/FIND_LIBRARY_USE_LIBX32_PATHS.rst
new file mode 100644
index 0000000..b87b09b
--- /dev/null
+++ b/Help/prop_gbl/FIND_LIBRARY_USE_LIBX32_PATHS.rst
@@ -0,0 +1,12 @@
+FIND_LIBRARY_USE_LIBX32_PATHS
+-----------------------------
+
+Whether the :command:`find_library` command should automatically search
+``libx32`` directories.
+
+``FIND_LIBRARY_USE_LIBX32_PATHS`` is a boolean specifying whether the
+:command:`find_library` command should automatically search the ``libx32``
+variant of directories called ``lib`` in the search path when building
+x32-abi binaries.
+
+See also the :variable:`CMAKE_FIND_LIBRARY_CUSTOM_LIB_SUFFIX` variable.
diff --git a/Help/variable/CMAKE_FIND_LIBRARY_CUSTOM_LIB_SUFFIX.rst b/Help/variable/CMAKE_FIND_LIBRARY_CUSTOM_LIB_SUFFIX.rst
index f7c6524..ada8955 100644
--- a/Help/variable/CMAKE_FIND_LIBRARY_CUSTOM_LIB_SUFFIX.rst
+++ b/Help/variable/CMAKE_FIND_LIBRARY_CUSTOM_LIB_SUFFIX.rst
@@ -9,3 +9,4 @@ This overrides the behavior of related global properties:
 
 * :prop_gbl:`FIND_LIBRARY_USE_LIB32_PATHS`
 * :prop_gbl:`FIND_LIBRARY_USE_LIB64_PATHS`
+* :prop_gbl:`FIND_LIBRARY_USE_LIBX32_PATHS`