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
The `add_library` and `add_executable` commands can now be called with
no source-files and won't generate a warning or error message, as long
as source-files will be added later via the `target_sources` command.
If during the generation step still no sources are associated with
targets created by such calls a useful error message will be generated
and generation fails.
Targets of type `INTERFACE_LIBRARY`, `UTILITY` or `GLOBAL_TARGET` are
excluded from this check because we do not need sources for these target
types during generation.
Fixes: #16872
Remove use of UseObjectLibraries from Makefile and Ninja generators. It
is not needed now because those generators use GetExternalObjects
which already contains the objects from object libraries.
The VS10 generator calls both the UseObjectLibraries and the GetExternalObjects
methods. Ensure that duplicates are not created by skipping objects
from object libraries in handling of GetExternalObjects.
Similarly, fix VS6, VS7 and Xcode object handling by skipping
external objects from OBJECT_LIBRARY usage as appropriate.
The error message in the BadSourceExpression1 test is now reported
by the generator expression evaluator, so it has different text.
