ObjC: Document ObjC/ObjCXX standard properties / variables

Fixes: #19919

15 files changed, 238 insertions, 1 deletions

diff --git a/Help/command/try_compile.rst b/Help/command/try_compile.rst
index 0bc2ca3..edbf92c 100644
--- a/Help/command/try_compile.rst
+++ b/Help/command/try_compile.rst
@@ -103,15 +103,18 @@ The options are:
 
 ``<LANG>_STANDARD <std>``
   Specify the :prop_tgt:`C_STANDARD`, :prop_tgt:`CXX_STANDARD`,
+  :prop_tgt:`OBJC_STANDARD`, :prop_tgt:`OBJCXX_STANDARD`,
   or :prop_tgt:`CUDA_STANDARD` target property of the generated project.
 
 ``<LANG>_STANDARD_REQUIRED <bool>``
   Specify the :prop_tgt:`C_STANDARD_REQUIRED`,
-  :prop_tgt:`CXX_STANDARD_REQUIRED`, or :prop_tgt:`CUDA_STANDARD_REQUIRED`
+  :prop_tgt:`CXX_STANDARD_REQUIRED`, :prop_tgt:`OBJC_STANDARD_REQUIRED`,
+  :prop_tgt:`OBJCXX_STANDARD_REQUIRED`,or :prop_tgt:`CUDA_STANDARD_REQUIRED`
   target property of the generated project.
 
 ``<LANG>_EXTENSIONS <bool>``
   Specify the :prop_tgt:`C_EXTENSIONS`, :prop_tgt:`CXX_EXTENSIONS`,
+  :prop_tgt:`OBJC_EXTENSIONS`, :prop_tgt:`OBJCXX_EXTENSIONS`,
   or :prop_tgt:`CUDA_EXTENSIONS` target property of the generated project.
 
 In this version all files in ``<bindir>/CMakeFiles/CMakeTmp`` will be
@@ -171,6 +174,12 @@ then the language standard variables are honored:
 * :variable:`CMAKE_CXX_STANDARD`
 * :variable:`CMAKE_CXX_STANDARD_REQUIRED`
 * :variable:`CMAKE_CXX_EXTENSIONS`
+* :variable:`CMAKE_OBJC_STANDARD`
+* :variable:`CMAKE_OBJC_STANDARD_REQUIRED`
+* :variable:`CMAKE_OBJC_EXTENSIONS`
+* :variable:`CMAKE_OBJCXX_STANDARD`
+* :variable:`CMAKE_OBJCXX_STANDARD_REQUIRED`
+* :variable:`CMAKE_OBJCXX_EXTENSIONS`
 * :variable:`CMAKE_CUDA_STANDARD`
 * :variable:`CMAKE_CUDA_STANDARD_REQUIRED`
 * :variable:`CMAKE_CUDA_EXTENSIONS`
diff --git a/Help/manual/cmake-properties.7.rst b/Help/manual/cmake-properties.7.rst
index a59dd6b..e704371 100644
--- a/Help/manual/cmake-properties.7.rst
+++ b/Help/manual/cmake-properties.7.rst
@@ -289,6 +289,12 @@ Properties on Targets
    /prop_tgt/NAME
    /prop_tgt/NO_SONAME
    /prop_tgt/NO_SYSTEM_FROM_IMPORTED
+   /prop_tgt/OBJC_EXTENSIONS
+   /prop_tgt/OBJC_STANDARD
+   /prop_tgt/OBJC_STANDARD_REQUIRED
+   /prop_tgt/OBJCXX_EXTENSIONS
+   /prop_tgt/OBJCXX_STANDARD
+   /prop_tgt/OBJCXX_STANDARD_REQUIRED
    /prop_tgt/OSX_ARCHITECTURES_CONFIG
    /prop_tgt/OSX_ARCHITECTURES
    /prop_tgt/OUTPUT_NAME_CONFIG
diff --git a/Help/manual/cmake-variables.7.rst b/Help/manual/cmake-variables.7.rst
index 360140c..53b7f8d 100644
--- a/Help/manual/cmake-variables.7.rst
+++ b/Help/manual/cmake-variables.7.rst
@@ -529,6 +529,12 @@ Variables for Languages
    /variable/CMAKE_LANG_SOURCE_FILE_EXTENSIONS
    /variable/CMAKE_LANG_STANDARD_INCLUDE_DIRECTORIES
    /variable/CMAKE_LANG_STANDARD_LIBRARIES
+   /variable/CMAKE_OBJC_EXTENSIONS
+   /variable/CMAKE_OBJC_STANDARD
+   /variable/CMAKE_OBJC_STANDARD_REQUIRED
+   /variable/CMAKE_OBJCXX_EXTENSIONS
+   /variable/CMAKE_OBJCXX_STANDARD
+   /variable/CMAKE_OBJCXX_STANDARD_REQUIRED
    /variable/CMAKE_Swift_LANGUAGE_VERSION
    /variable/CMAKE_USER_MAKE_RULES_OVERRIDE_LANG
 
diff --git a/Help/prop_tgt/OBJCXX_EXTENSIONS.rst b/Help/prop_tgt/OBJCXX_EXTENSIONS.rst
new file mode 100644
index 0000000..9f9d804
--- /dev/null
+++ b/Help/prop_tgt/OBJCXX_EXTENSIONS.rst
@@ -0,0 +1,20 @@
+OBJCXX_EXTENSIONS
+-----------------
+
+Boolean specifying whether compiler specific extensions are requested.
+
+This property specifies whether compiler specific extensions should be
+used.  For some compilers, this results in adding a flag such
+as ``-std=gnu++11`` instead of ``-std=c++11`` to the compile line.  This
+property is ``ON`` by default. The basic ObjC++ standard level is
+controlled by the :prop_tgt:`OBJCXX_STANDARD` target property.
+
+See the :manual:`cmake-compile-features(7)` manual for information on
+compile features and a list of supported compilers.
+
+If the property is not set, and the project has set the :prop_tgt:`CXX_EXTENSIONS`,
+the value of :prop_tgt:`CXX_EXTENSIONS` is set for :prop_tgt:`OBJCXX_EXTENSIONS`.
+
+This property is initialized by the value of
+the :variable:`CMAKE_OBJCXX_EXTENSIONS` variable if it is set when a target
+is created.
diff --git a/Help/prop_tgt/OBJCXX_STANDARD.rst b/Help/prop_tgt/OBJCXX_STANDARD.rst
new file mode 100644
index 0000000..3c925dc
--- /dev/null
+++ b/Help/prop_tgt/OBJCXX_STANDARD.rst
@@ -0,0 +1,35 @@
+OBJCXX_STANDARD
+---------------
+
+The ObjC++ standard whose features are requested to build this target.
+
+This property specifies the ObjC++ standard whose features are requested
+to build this target.  For some compilers, this results in adding a
+flag such as ``-std=gnu++11`` to the compile line.
+
+Supported values are ``98``, ``11``, ``14``, ``17``, and ``20``.
+
+If the value requested does not result in a compile flag being added for
+the compiler in use, a previous standard flag will be added instead.  This
+means that using:
+
+.. code-block:: cmake
+
+  set_property(TARGET tgt PROPERTY OBJCXX_STANDARD 11)
+
+with a compiler which does not support ``-std=gnu++11`` or an equivalent
+flag will not result in an error or warning, but will instead add the
+``-std=gnu++98`` flag if supported.  This "decay" behavior may be controlled
+with the :prop_tgt:`OBJCXX_STANDARD_REQUIRED` target property.
+Additionally, the :prop_tgt:`OBJCXX_EXTENSIONS` target property may be used to
+control whether compiler-specific extensions are enabled on a per-target basis.
+
+If the property is not set, and the project has set the :prop_tgt:`CXX_STANDARD`,
+the value of :prop_tgt:`CXX_STANDARD` is set for :prop_tgt:`OBJCXX_STANDARD`.
+
+See the :manual:`cmake-compile-features(7)` manual for information on
+compile features and a list of supported compilers.
+
+This property is initialized by the value of
+the :variable:`CMAKE_OBJCXX_STANDARD` variable if it is set when a target
+is created.
diff --git a/Help/prop_tgt/OBJCXX_STANDARD_REQUIRED.rst b/Help/prop_tgt/OBJCXX_STANDARD_REQUIRED.rst
new file mode 100644
index 0000000..c330abf
--- /dev/null
+++ b/Help/prop_tgt/OBJCXX_STANDARD_REQUIRED.rst
@@ -0,0 +1,20 @@
+OBJCXX_STANDARD_REQUIRED
+------------------------
+
+Boolean describing whether the value of :prop_tgt:`OBJCXX_STANDARD` is a requirement.
+
+If this property is set to ``ON``, then the value of the
+:prop_tgt:`OBJCXX_STANDARD` target property is treated as a requirement.  If this
+property is ``OFF`` or unset, the :prop_tgt:`OBJCXX_STANDARD` target property is
+treated as optional and may "decay" to a previous standard if the requested is
+not available.
+
+If the property is not set, and the project has set the :prop_tgt:`CXX_STANDARD_REQUIRED`,
+the value of :prop_tgt:`CXX_STANDARD_REQUIRED` is set for :prop_tgt:`OBJCXX_STANDARD_REQUIRED`.
+
+See the :manual:`cmake-compile-features(7)` manual for information on
+compile features and a list of supported compilers.
+
+This property is initialized by the value of
+the :variable:`CMAKE_OBJCXX_STANDARD_REQUIRED` variable if it is set when a
+target is created.
diff --git a/Help/prop_tgt/OBJC_EXTENSIONS.rst b/Help/prop_tgt/OBJC_EXTENSIONS.rst
new file mode 100644
index 0000000..2de9e48
--- /dev/null
+++ b/Help/prop_tgt/OBJC_EXTENSIONS.rst
@@ -0,0 +1,20 @@
+OBJC_EXTENSIONS
+---------------
+
+Boolean specifying whether compiler specific extensions are requested.
+
+This property specifies whether compiler specific extensions should be
+used.  For some compilers, this results in adding a flag such
+as ``-std=gnu11`` instead of ``-std=c11`` to the compile line.  This
+property is ``ON`` by default. The basic OBJC standard level is
+controlled by the :prop_tgt:`OBJC_STANDARD` target property.
+
+If the property is not set, and the project has set the :prop_tgt:`C_EXTENSIONS`,
+the value of :prop_tgt:`C_EXTENSIONS` is set for :prop_tgt:`OBJC_EXTENSIONS`.
+
+See the :manual:`cmake-compile-features(7)` manual for information on
+compile features and a list of supported compilers.
+
+This property is initialized by the value of
+the :variable:`CMAKE_OBJC_EXTENSIONS` variable if it is set when a target
+is created.
diff --git a/Help/prop_tgt/OBJC_STANDARD.rst b/Help/prop_tgt/OBJC_STANDARD.rst
new file mode 100644
index 0000000..d1e1b24
--- /dev/null
+++ b/Help/prop_tgt/OBJC_STANDARD.rst
@@ -0,0 +1,35 @@
+OBJC_STANDARD
+-------------
+
+The OBJC standard whose features are requested to build this target.
+
+This property specifies the OBJC standard whose features are requested
+to build this target.  For some compilers, this results in adding a
+flag such as ``-std=gnu11`` to the compile line.
+
+Supported values are ``90``, ``99`` and ``11``.
+
+If the value requested does not result in a compile flag being added for
+the compiler in use, a previous standard flag will be added instead.  This
+means that using:
+
+.. code-block:: cmake
+
+  set_property(TARGET tgt PROPERTY OBJC_STANDARD 11)
+
+with a compiler which does not support ``-std=gnu11`` or an equivalent
+flag will not result in an error or warning, but will instead add the
+``-std=gnu99`` or ``-std=gnu90`` flag if supported.  This "decay" behavior may
+be controlled with the :prop_tgt:`OBJC_STANDARD_REQUIRED` target property.
+Additionally, the :prop_tgt:`OBJC_EXTENSIONS` target property may be used to
+control whether compiler-specific extensions are enabled on a per-target basis.
+
+If the property is not set, and the project has set the :prop_tgt:`C_STANDARD`,
+the value of :prop_tgt:`C_STANDARD` is set for :prop_tgt:`OBJC_STANDARD`.
+
+See the :manual:`cmake-compile-features(7)` manual for information on
+compile features and a list of supported compilers.
+
+This property is initialized by the value of
+the :variable:`CMAKE_OBJC_STANDARD` variable if it is set when a target
+is created.
diff --git a/Help/prop_tgt/OBJC_STANDARD_REQUIRED.rst b/Help/prop_tgt/OBJC_STANDARD_REQUIRED.rst
new file mode 100644
index 0000000..8cf377c
--- /dev/null
+++ b/Help/prop_tgt/OBJC_STANDARD_REQUIRED.rst
@@ -0,0 +1,20 @@
+OBJC_STANDARD_REQUIRED
+----------------------
+
+Boolean describing whether the value of :prop_tgt:`OBJC_STANDARD` is a requirement.
+
+If this property is set to ``ON``, then the value of the
+:prop_tgt:`OBJC_STANDARD` target property is treated as a requirement.  If this
+property is ``OFF`` or unset, the :prop_tgt:`OBJC_STANDARD` target property is
+treated as optional and may "decay" to a previous standard if the requested is
+not available.
+
+If the property is not set, and the project has set the :prop_tgt:`C_STANDARD_REQUIRED`,
+the value of :prop_tgt:`C_STANDARD_REQUIRED` is set for :prop_tgt:`OBJC_STANDARD_REQUIRED`.
+
+See the :manual:`cmake-compile-features(7)` manual for information on
+compile features and a list of supported compilers.
+
+This property is initialized by the value of
+the :variable:`CMAKE_OBJC_STANDARD_REQUIRED` variable if it is set when a
+target is created.
diff --git a/Help/variable/CMAKE_OBJCXX_EXTENSIONS.rst b/Help/variable/CMAKE_OBJCXX_EXTENSIONS.rst
new file mode 100644
index 0000000..8afa6f2
--- /dev/null
+++ b/Help/variable/CMAKE_OBJCXX_EXTENSIONS.rst
@@ -0,0 +1,11 @@
+CMAKE_OBJCXX_EXTENSIONS
+-----------------------
+
+Default value for :prop_tgt:`OBJCXX_EXTENSIONS` property of targets.
+
+This variable is used to initialize the :prop_tgt:`OBJCXX_EXTENSIONS`
+property on all targets.  See that target property for additional
+information.
+
+See the :manual:`cmake-compile-features(7)` manual for information on
+compile features and a list of supported compilers.
diff --git a/Help/variable/CMAKE_OBJCXX_STANDARD.rst b/Help/variable/CMAKE_OBJCXX_STANDARD.rst
new file mode 100644
index 0000000..4e5016a
--- /dev/null
+++ b/Help/variable/CMAKE_OBJCXX_STANDARD.rst
@@ -0,0 +1,11 @@
+CMAKE_OBJCXX_STANDARD
+---------------------
+
+Default value for :prop_tgt:`OBJCXX_STANDARD` property of targets.
+
+This variable is used to initialize the :prop_tgt:`OBJCXX_STANDARD`
+property on all targets.  See that target property for additional
+information.
+
+See the :manual:`cmake-compile-features(7)` manual for information on
+compile features and a list of supported compilers.
diff --git a/Help/variable/CMAKE_OBJCXX_STANDARD_REQUIRED.rst b/Help/variable/CMAKE_OBJCXX_STANDARD_REQUIRED.rst
new file mode 100644
index 0000000..3a0602a
--- /dev/null
+++ b/Help/variable/CMAKE_OBJCXX_STANDARD_REQUIRED.rst
@@ -0,0 +1,11 @@
+CMAKE_OBJCXX_STANDARD_REQUIRED
+------------------------------
+
+Default value for :prop_tgt:`OBJCXX_STANDARD_REQUIRED` property of targets.
+
+This variable is used to initialize the :prop_tgt:`OBJCXX_STANDARD_REQUIRED`
+property on all targets.  See that target property for additional
+information.
+
+See the :manual:`cmake-compile-features(7)` manual for information on
+compile features and a list of supported compilers.
diff --git a/Help/variable/CMAKE_OBJC_EXTENSIONS.rst b/Help/variable/CMAKE_OBJC_EXTENSIONS.rst
new file mode 100644
index 0000000..d9619d8
--- /dev/null
+++ b/Help/variable/CMAKE_OBJC_EXTENSIONS.rst
@@ -0,0 +1,11 @@
+CMAKE_OBJC_EXTENSIONS
+---------------------
+
+Default value for :prop_tgt:`OBJC_EXTENSIONS` property of targets.
+
+This variable is used to initialize the :prop_tgt:`OBJC_EXTENSIONS`
+property on all targets.  See that target property for additional
+information.
+
+See the :manual:`cmake-compile-features(7)` manual for information on
+compile features and a list of supported compilers.
diff --git a/Help/variable/CMAKE_OBJC_STANDARD.rst b/Help/variable/CMAKE_OBJC_STANDARD.rst
new file mode 100644
index 0000000..976c441
--- /dev/null
+++ b/Help/variable/CMAKE_OBJC_STANDARD.rst
@@ -0,0 +1,11 @@
+CMAKE_OBJC_STANDARD
+-------------------
+
+Default value for :prop_tgt:`OBJC_STANDARD` property of targets.
+
+This variable is used to initialize the :prop_tgt:`OBJC_STANDARD`
+property on all targets.  See that target property for additional
+information.
+
+See the :manual:`cmake-compile-features(7)` manual for information on
+compile features and a list of supported compilers.
diff --git a/Help/variable/CMAKE_OBJC_STANDARD_REQUIRED.rst b/Help/variable/CMAKE_OBJC_STANDARD_REQUIRED.rst
new file mode 100644
index 0000000..5c02096
--- /dev/null
+++ b/Help/variable/CMAKE_OBJC_STANDARD_REQUIRED.rst
@@ -0,0 +1,11 @@
+CMAKE_OBJC_STANDARD_REQUIRED
+----------------------------
+
+Default value for :prop_tgt:`OBJC_STANDARD_REQUIRED` property of targets.
+
+This variable is used to initialize the :prop_tgt:`OBJC_STANDARD_REQUIRED`
+property on all targets.  See that target property for additional
+information.
+
+See the :manual:`cmake-compile-features(7)` manual for information on
+compile features and a list of supported compilers.