Make it even clearer that for the signature `<version>...<version>` that
the second value is only used for policies, and is not a clamp range
of supported CMake versions.
The CMAKE_MINIMUM_REQUIRED_VERSION has long been set by
the cmake_minimum_required() command, but the command docs
never mentioned this. Only the variable's own docs stated this but
the variable isn't very discoverable without it being mentioned in
the command's docs as well.
This change ony concerns directives that appear in the document body.
The guidelines for inserting version directives:
* Baseline version is CMake 3.0, i.e. directives start at 3.1.
* Always use `.. versionadded::` directive, avoid ad-hoc version
references. Exception: policy pages.
* For new command signatures, put `versionadded` on a separate line
after the signature.
* For a group of new signatures in a new document section,
a single version note at the beginning of the section is sufficient.
* For new options, put `versionadded` on a separate line before
option description.
* If all the option descriptions in the list are short one-liners,
it's fine to put `versionadded` on the same line as the description.
* If multiple option descriptions in close proximity would have
the same ..versionadded directive, consider adding a single
directive after the list, mentioning all added options.
* For compact value lists and sub-option lists, put a single
`versionadded` directive after the list mentioning all additions.
* When a change is described in a single paragraph, put
`versionadded` into that paragraph.
* When only part of the paragraph has changed, separate the changed
part if it doesn't break the flow. Otherwise, write a follow-up
clarification paragraph and apply version directive to that.
* When multiple version directives are close by, order earlier
additions before later additions.
* Indent related lists and code blocks to include them in the scope
of `versionadded` directive.
Issue: #19715
Revise docs for all "Scripting Commands", except four find_XXX
that use a macro suite of their own.
* Take full advantage of the improved syntax highlighting.
* Make consequential use of <..> placeholders.
* Clarify things here and there in the text.
Specific improvements to some command docs:
* "math": Correct description of novel hexadecimal capability.
* "if", "foreach", "while": Provide link to "endif" etc
* "foreach", "while": Mention "break" and "continue".
* "foreach": Simplify explanation of ``RANGE`` and ``IN`` signatures;
advise against negative arguments or reverse ranges (compare issue #18461)
* "endif", "endfunction" etc: Explain that the argument is optional and
maintained for compatibility only
Teach `cmake_minimum_required` and `cmake_policy(VERSION)` to support a
version range of the form `<min>[...<max>]`. Define this to mean that
version `<min>` is required, but known policies up to those introduced
by `<max>` will be set to `NEW`. This will allow projects to easily
specify a range of versions for which they have been updated.
Implementation indicates that at least two components of VERSION must
be specified (see Source/cmCMakeMinimumRequired.cxx.) Therefore the
minor version is not optional.
Many projects put their project() call first, but the actions taken
by this command can be influenced by policies and other information
set by a call to cmake_minimum_required. Document in each of these
two commands that cmake_minimum_required should be called first.
Suggested-by: Alan W. Irwin
