cmake: Allow CMAKE_CONFIGURATION_TYPES to be set by environment variable

When no `CMAKE_CONFIGURATION_TYPES` is explicitly specified while
creating a new build tree, check for an environment variable of the same
name.

Issue: #20983

4 files changed, 19 insertions, 1 deletions

diff --git a/Help/envvar/CMAKE_CONFIGURATION_TYPES.rst b/Help/envvar/CMAKE_CONFIGURATION_TYPES.rst
new file mode 100644
index 0000000..833aa4a
--- /dev/null
+++ b/Help/envvar/CMAKE_CONFIGURATION_TYPES.rst
@@ -0,0 +1,11 @@
+CMAKE_CONFIGURATION_TYPES
+-------------------------
+
+.. versionadded:: 3.22
+
+.. include:: ENV_VAR.txt
+
+The ``CMAKE_CONFIGURATION_TYPES`` environment variable specifies a
+default value for the :variable:`CMAKE_CONFIGURATION_TYPES` variable
+when there is no explicit configuration given on the first run while
+creating a new build tree.
diff --git a/Help/manual/cmake-env-variables.7.rst b/Help/manual/cmake-env-variables.7.rst
index ab974a0..3db189e 100644
--- a/Help/manual/cmake-env-variables.7.rst
+++ b/Help/manual/cmake-env-variables.7.rst
@@ -31,6 +31,7 @@ Environment Variables that Control the Build
    /envvar/CMAKE_APPLE_SILICON_PROCESSOR
    /envvar/CMAKE_BUILD_PARALLEL_LEVEL
    /envvar/CMAKE_BUILD_TYPE
+   /envvar/CMAKE_CONFIGURATION_TYPES
    /envvar/CMAKE_CONFIG_TYPE
    /envvar/CMAKE_EXPORT_COMPILE_COMMANDS
    /envvar/CMAKE_GENERATOR
diff --git a/Help/release/dev/env-init-configs.rst b/Help/release/dev/env-init-configs.rst
index fe334b7..5c9892d 100644
--- a/Help/release/dev/env-init-configs.rst
+++ b/Help/release/dev/env-init-configs.rst
@@ -3,3 +3,7 @@ env-init-configs
 
 * The :envvar:`CMAKE_BUILD_TYPE` environment variable was added to
   provide a default value for the :variable:`CMAKE_BUILD_TYPE` variable.
+
+* The :envvar:`CMAKE_CONFIGURATION_TYPES` environment variable was added to
+  provide a default value for the :variable:`CMAKE_CONFIGURATION_TYPES`
+  variable.
diff --git a/Help/variable/CMAKE_CONFIGURATION_TYPES.rst b/Help/variable/CMAKE_CONFIGURATION_TYPES.rst
index 15fea4b..5298a72 100644
--- a/Help/variable/CMAKE_CONFIGURATION_TYPES.rst
+++ b/Help/variable/CMAKE_CONFIGURATION_TYPES.rst
@@ -10,7 +10,9 @@ types.
 
 This variable is initialized by the first :command:`project` or
 :command:`enable_language` command called in a project when a new build
-tree is first created.  The default value is generator-specific.
+tree is first created.  If the :envvar:`CMAKE_CONFIGURATION_TYPES`
+environment variable is set, its value is used.  Otherwise, the default
+value is generator-specific.
 
 See :variable:`CMAKE_BUILD_TYPE` for specifying the configuration with
 single-config generators.