project: Manage VERSION variables

Teach the project() command to set variables

  {PROJECT,<PROJECT-NAME>}_VERSION{,_MAJOR,_MINOR,_PATCH,_TWEAK}

holding the project version number and its components.  Add project()
command option "VERSION" to specify the version explicitly, and default
to the empty string when it is not given.

Since this clears variables when no VERSION is given, this may change
behavior for existing projects that set the version variables themselves
prior to calling project().  Add policy CMP0048 for compatibility.

Suggested-by: Alex Neundorf <neundorf@kde.org>

14 files changed, 121 insertions, 1 deletions

diff --git a/Help/command/project.rst b/Help/command/project.rst
index aabab65..c601a01 100644
--- a/Help/command/project.rst
+++ b/Help/command/project.rst
@@ -1,11 +1,14 @@
 project
 -------
 
-Set a name and enable languages for the entire project.
+Set a name, version, and enable languages for the entire project.
 
 .. code-block:: cmake
 
  project(<PROJECT-NAME> [LANGUAGES] [<language-name>...])
+ project(<PROJECT-NAME>
+         [VERSION <major>[.<minor>[.<patch>[.<tweak>]]]]
+         [LANGUAGES <language-name>...])
 
 Sets the name of the project and stores the name in the
 :variable:`PROJECT_NAME` variable.  Additionally this sets variables
@@ -15,6 +18,28 @@ Sets the name of the project and stores the name in the
 * :variable:`PROJECT_BINARY_DIR`,
   :variable:`<PROJECT-NAME>_BINARY_DIR`
 
+If ``VERSION`` is specified, given components must be non-negative integers.
+If ``VERSION`` is not specified, the default version is the empty string.
+The ``VERSION`` option may not be used unless policy :policy:`CMP0048` is
+set to ``NEW``.
+
+The :command:`project()` command stores the version number and its components
+in variables
+
+* :variable:`PROJECT_VERSION`,
+  :variable:`<PROJECT-NAME>_VERSION`
+* :variable:`PROJECT_VERSION_MAJOR`,
+  :variable:`<PROJECT-NAME>_VERSION_MAJOR`
+* :variable:`PROJECT_VERSION_MINOR`,
+  :variable:`<PROJECT-NAME>_VERSION_MINOR`
+* :variable:`PROJECT_VERSION_PATCH`,
+  :variable:`<PROJECT-NAME>_VERSION_PATCH`
+* :variable:`PROJECT_VERSION_TWEAK`,
+  :variable:`<PROJECT-NAME>_VERSION_TWEAK`
+
+Variables corresponding to unspecified versions are set to the empty string
+(if policy :policy:`CMP0048` is set to ``NEW``).
+
 Optionally you can specify which languages your project supports.
 Example languages are ``C``, ``CXX`` (i.e.  C++), ``Fortran``, etc.
 By default ``C`` and ``CXX`` are enabled if no language options are
diff --git a/Help/manual/cmake-policies.7.rst b/Help/manual/cmake-policies.7.rst
index 02f596b..5a9ec95 100644
--- a/Help/manual/cmake-policies.7.rst
+++ b/Help/manual/cmake-policies.7.rst
@@ -99,3 +99,4 @@ All Policies
    /policy/CMP0045
    /policy/CMP0046
    /policy/CMP0047
+   /policy/CMP0048
diff --git a/Help/manual/cmake-variables.7.rst b/Help/manual/cmake-variables.7.rst
index f363f94..c4ae193 100644
--- a/Help/manual/cmake-variables.7.rst
+++ b/Help/manual/cmake-variables.7.rst
@@ -79,7 +79,17 @@ Variables that Provide Information
    /variable/PROJECT-NAME_BINARY_DIR
    /variable/PROJECT_NAME
    /variable/PROJECT-NAME_SOURCE_DIR
+   /variable/PROJECT-NAME_VERSION
+   /variable/PROJECT-NAME_VERSION_MAJOR
+   /variable/PROJECT-NAME_VERSION_MINOR
+   /variable/PROJECT-NAME_VERSION_PATCH
+   /variable/PROJECT-NAME_VERSION_TWEAK
    /variable/PROJECT_SOURCE_DIR
+   /variable/PROJECT_VERSION
+   /variable/PROJECT_VERSION_MAJOR
+   /variable/PROJECT_VERSION_MINOR
+   /variable/PROJECT_VERSION_PATCH
+   /variable/PROJECT_VERSION_TWEAK
 
 Variables that Change Behavior
 ==============================
diff --git a/Help/policy/CMP0048.rst b/Help/policy/CMP0048.rst
new file mode 100644
index 0000000..ae51329
--- /dev/null
+++ b/Help/policy/CMP0048.rst
@@ -0,0 +1,22 @@
+CMP0048
+-------
+
+The :command:`project` command manages VERSION variables.
+
+CMake version 3.0.0 introduced the ``VERSION`` option of the :command:`project`
+command to specify a project version as well as the name.  In order to keep
+:variable:`PROJECT_VERSION` and related variables consistent with variable
+:variable:`PROJECT_NAME` it is necessary to set the VERSION variables
+to the empty string when no ``VERSION`` is given to :command:`project`.
+However, this can change behavior for existing projects that set VERSION
+variables themselves since :command:`project` may now clear them.
+This policy controls the behavior for compatibility with such projects.
+
+The OLD behavior for this policy is to leave VERSION variables untouched.
+The NEW behavior for this policy is to set VERSION as documented by the
+:command:`project` command.
+
+This policy was introduced in CMake version 3.0.0.
+CMake version |release| warns when the policy is not set and uses
+OLD behavior.  Use the cmake_policy command to set it to OLD or
+NEW explicitly.
diff --git a/Help/variable/PROJECT-NAME_VERSION.rst b/Help/variable/PROJECT-NAME_VERSION.rst
new file mode 100644
index 0000000..0f6ed51
--- /dev/null
+++ b/Help/variable/PROJECT-NAME_VERSION.rst
@@ -0,0 +1,11 @@
+<PROJECT-NAME>_VERSION
+----------------------
+
+Value given to the ``VERSION`` option of the most recent call to the
+:command:`project` command with project name ``<PROJECT-NAME>``, if any.
+
+See also the component-wise version variables
+:variable:`<PROJECT-NAME>_VERSION_MAJOR`,
+:variable:`<PROJECT-NAME>_VERSION_MINOR`,
+:variable:`<PROJECT-NAME>_VERSION_PATCH`, and
+:variable:`<PROJECT-NAME>_VERSION_TWEAK`.
diff --git a/Help/variable/PROJECT-NAME_VERSION_MAJOR.rst b/Help/variable/PROJECT-NAME_VERSION_MAJOR.rst
new file mode 100644
index 0000000..9e2d755
--- /dev/null
+++ b/Help/variable/PROJECT-NAME_VERSION_MAJOR.rst
@@ -0,0 +1,5 @@
+<PROJECT-NAME>_VERSION_MAJOR
+----------------------------
+
+First version number component of the :variable:`<PROJECT-NAME>_VERSION`
+variable as set by the :command:`project` command.
diff --git a/Help/variable/PROJECT-NAME_VERSION_MINOR.rst b/Help/variable/PROJECT-NAME_VERSION_MINOR.rst
new file mode 100644
index 0000000..fa2cdab
--- /dev/null
+++ b/Help/variable/PROJECT-NAME_VERSION_MINOR.rst
@@ -0,0 +1,5 @@
+<PROJECT-NAME>_VERSION_MINOR
+----------------------------
+
+Second version number component of the :variable:`<PROJECT-NAME>_VERSION`
+variable as set by the :command:`project` command.
diff --git a/Help/variable/PROJECT-NAME_VERSION_PATCH.rst b/Help/variable/PROJECT-NAME_VERSION_PATCH.rst
new file mode 100644
index 0000000..85b5e6b
--- /dev/null
+++ b/Help/variable/PROJECT-NAME_VERSION_PATCH.rst
@@ -0,0 +1,5 @@
+<PROJECT-NAME>_VERSION_PATCH
+----------------------------
+
+Third version number component of the :variable:`<PROJECT-NAME>_VERSION`
+variable as set by the :command:`project` command.
diff --git a/Help/variable/PROJECT-NAME_VERSION_TWEAK.rst b/Help/variable/PROJECT-NAME_VERSION_TWEAK.rst
new file mode 100644
index 0000000..65c4044
--- /dev/null
+++ b/Help/variable/PROJECT-NAME_VERSION_TWEAK.rst
@@ -0,0 +1,5 @@
+<PROJECT-NAME>_VERSION_TWEAK
+----------------------------
+
+Fourth version number component of the :variable:`<PROJECT-NAME>_VERSION`
+variable as set by the :command:`project` command.
diff --git a/Help/variable/PROJECT_VERSION.rst b/Help/variable/PROJECT_VERSION.rst
new file mode 100644
index 0000000..234558d
--- /dev/null
+++ b/Help/variable/PROJECT_VERSION.rst
@@ -0,0 +1,11 @@
+PROJECT_VERSION
+---------------
+
+Value given to the ``VERSION`` option of the most recent call to the
+:command:`project` command, if any.
+
+See also the component-wise version variables
+:variable:`PROJECT_VERSION_MAJOR`,
+:variable:`PROJECT_VERSION_MINOR`,
+:variable:`PROJECT_VERSION_PATCH`, and
+:variable:`PROJECT_VERSION_TWEAK`.
diff --git a/Help/variable/PROJECT_VERSION_MAJOR.rst b/Help/variable/PROJECT_VERSION_MAJOR.rst
new file mode 100644
index 0000000..4b6072c
--- /dev/null
+++ b/Help/variable/PROJECT_VERSION_MAJOR.rst
@@ -0,0 +1,5 @@
+PROJECT_VERSION_MAJOR
+---------------------
+
+First version number component of the :variable:`PROJECT_VERSION`
+variable as set by the :command:`project` command.
diff --git a/Help/variable/PROJECT_VERSION_MINOR.rst b/Help/variable/PROJECT_VERSION_MINOR.rst
new file mode 100644
index 0000000..5f31220
--- /dev/null
+++ b/Help/variable/PROJECT_VERSION_MINOR.rst
@@ -0,0 +1,5 @@
+PROJECT_VERSION_MINOR
+---------------------
+
+Second version number component of the :variable:`PROJECT_VERSION`
+variable as set by the :command:`project` command.
diff --git a/Help/variable/PROJECT_VERSION_PATCH.rst b/Help/variable/PROJECT_VERSION_PATCH.rst
new file mode 100644
index 0000000..ac72ec0
--- /dev/null
+++ b/Help/variable/PROJECT_VERSION_PATCH.rst
@@ -0,0 +1,5 @@
+PROJECT_VERSION_PATCH
+---------------------
+
+Third version number component of the :variable:`PROJECT_VERSION`
+variable as set by the :command:`project` command.
diff --git a/Help/variable/PROJECT_VERSION_TWEAK.rst b/Help/variable/PROJECT_VERSION_TWEAK.rst
new file mode 100644
index 0000000..d7f96d6
--- /dev/null
+++ b/Help/variable/PROJECT_VERSION_TWEAK.rst
@@ -0,0 +1,5 @@
+PROJECT_VERSION_TWEAK
+---------------------
+
+Fourth version number component of the :variable:`PROJECT_VERSION`
+variable as set by the :command:`project` command.