file(DOWNLOAD|UPLOAD): Add CMAKE_TLS_VERSION environment variable

Issue: #25701

Help/envvar/CMAKE_TLS_VERSION.rst

@@ -0,0 +1,12 @@
+CMAKE_TLS_VERSION
+-----------------
+
+.. versionadded:: 3.30
+
+.. include:: ENV_VAR.txt
+
+Specify the default value for the :command:`file(DOWNLOAD)` and
+:command:`file(UPLOAD)` commands' ``TLS_VERSION`` option.
+This environment variable is used if the option is not given
+and the :variable:`CMAKE_TLS_VERSION` cmake variable is not set.
+See that variable for allowed values.

Help/manual/cmake-env-variables.7.rst

@@ -27,6 +27,7 @@ Environment Variables that Change Behavior
    /envvar/CMAKE_MAXIMUM_RECURSION_DEPTH
    /envvar/CMAKE_PREFIX_PATH
    /envvar/CMAKE_PROGRAM_PATH
+   /envvar/CMAKE_TLS_VERSION
    /envvar/SSL_CERT_DIR
    /envvar/SSL_CERT_FILE
 

Help/release/dev/curl-tls-version.rst

@@ -5,6 +5,7 @@ curl-tls-version
   gained a ``TLS_VERSION <min>`` option to specify the minimum TLS
   version for connections to ``https://`` URLs.
 
-* The :variable:`CMAKE_TLS_VERSION` variable was added to specify a
-  default minimum TLS version for connections to ``https://`` URLs by
-  the :command:`file(DOWNLOAD)` and :command:`file(UPLOAD)` commands.
+* The :variable:`CMAKE_TLS_VERSION` variable and :envvar:`CMAKE_TLS_VERSION`
+  environment variable were added to specify a default minimum TLS version
+  for connections to ``https://`` URLs by the :command:`file(DOWNLOAD)`
+  and :command:`file(UPLOAD)` commands.

Help/variable/CMAKE_TLS_VERSION.rst

@@ -5,6 +5,8 @@ CMAKE_TLS_VERSION
 
 Specify the default value for the :command:`file(DOWNLOAD)` and
 :command:`file(UPLOAD)` commands' ``TLS_VERSION`` option.
+If this variable is not set, the commands check the
+:envvar:`CMAKE_TLS_VERSION` environment variable.
 
 The value may be one of: