Projects should always have specified one of PRE_BUILD, PRE_LINK or
POST_BUILD, and the documentation has always shown that one must
be given. But the argument parsing logic was such that if none was given,
POST_BUILD would be used and no error or warning would be raised.
Projects may be relying on this behavior, so document it as formally
supported, but not recommended.
Fixes: #23488
The previous wording contradicted itself regarding whether
Visual Studio generators were supported, and about when
generator expressions could be used. Restructure the paragraphs
and max it clearer what support was added in which CMake
versions.
Transform the depfile into MSBuild `AdditionalInputs` content. Add
MSBuild Targets to update `AdditionalInputs` and the `.tlog` files for
future builds without actually modifying the `.vcxproj` file.
Fixes: #20286
OUTPUT variant with a TARGET given to allow resolving target-based generator
expressions wouldn't work because OUTPUT is resolved before generator targets
are created, i.e. FindGeneratorTargetToUse() returns nullptr.
This is a known limitation, see #21364.
Implements #21336.
This facility is very useful for 'Ninja Multi-Config' and required
as well for future support of DEPFILE in 'Xcode' and 'Visual Studio'
generators (#20286).
Since commit c2dc7e0f53 (Help: Convert genex documentation to sphinx
domain objects, 2021-01-15) we can use `:genex:` cross-references to
link to named generator expressions. Update some places to do this.
This is meant to demonstrate the capability, not as a comprehensive
sweep.
Update the documentation added by commit c257c25419
(add_custom_{command,target}: Add genex support to OUTPUT and
BYPRODUCTS, 2020-10-19) to use sphinx markup instead of prose to specify
the version in which the feature was added.
Move rejection of `#`, `<`, and `>` characters in outputs and byproducts
to a generate-time check. This removes the front-end check that
disallowed generator expressions. The generators have already been
updated to handle them.
Fixes: #12877
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
Only generate a graph dependency between a custom command and
a target when the custom command queries for the file path
of an artifact of the target.
This makes generator expressions such as `TARGET_FILE_DIR`
behave the same way as `TARGET_PROPERTY` which never generated
a graph dependency.
- Mention the Makefile Generators' `make clean` removal in the
BYPRODUCTS section of add_custom_command and add_custom_target
- Expand the GENERATED property docs' description of which files will
be marked with the property, and of what it implies (including
`make clean` removal)
In commit f5126badd8 (add_custom_command: convert DEPENDS path arguments
to absolute paths, 2019-12-18, v3.17.0-rc1~263^2) we updated the
documentation to describe the behavior introduced by that commit.
However, the behavior was removed again by commit fd0ba705ce
(add_custom_command: check if a relative path should be an in-source
path, 2020-01-09, v3.17.0-rc1~141^2~4) without updating the
documentation.
Update the documentation again to describe the behavior as of the latter
commit. Spell out the steps that `cmLocalGenerator::GetRealDependency`
and `cmTargetTraceDependencies::IsUtility` use to add file-level and
target-level dependencies.
Target-level dependencies to utility targets are added from another target if
the other target requires a byproduct of the utility target or if it requires a
byproduct of PRE_BUILD, PRE_LINK, or POST_BUILD build events of a target.
Issue: #19005
Provide a way for custom commands and targets to set the pool variable
of the ninja build statement. Setting `JOB_POOL` is not compatible with
`USES_TERMINAL`, which implies the `console` pool.
The option is silently ignored with other generators.
Closes: #18483
Provide a way for custom commands to inform the ninja build tool about
their implicit dependencies. For now simply make use of the option an
error on other generators.
Closes: #15479
Teach the `add_custom_command` and `add_custom_target' commands to
substitute argv0 with the crosscompiling emulator if it is a target with
the `CROSSCOMPILING_EMULATOR` property set.
When documenting in the COMMAND option how to reference an executable,
we previously only explicitly covered how to do it for argv[0] and left
it to the reader to follow the reference to the generator expressions
manual. Add explicit mention of the TARGET_FILE genex in this
documentation since it will be a commonly used generator expression in
this context.
A common idiom in CMake-based build systems is to have custom commands
that generate files not listed explicitly as outputs so that these
files do not have to be newer than the inputs. The file modification
times of such "byproducts" are updated only when their content changes.
Then other build rules can depend on the byproducts explicitly so that
their dependents rebuild when the content of the original byproducts
really does change.
This "undeclared byproduct" approach is necessary for Makefile, VS, and
Xcode build tools because if a byproduct were listed as an output of a
rule then the rule would always rerun when the input is newer than the
byproduct but the byproduct may never be updated.
Ninja solves this problem by offering a 'restat' feature to check
whether an output was really modified after running a rule and tracking
the fact that it is up to date separately from its timestamp. However,
Ninja also stats all dependencies up front and will only restat files
that are listed as outputs of rules with the 'restat' option enabled.
Therefore an undeclared byproduct that does not exist at the start of
the build will be considered missing and the build will fail even if
other dependencies would cause the byproduct to be available before its
dependents build.
CMake works around this limitation by adding 'phony' build rules for
custom command dependencies in the build tree that do not have any
explicit specification of what produces them. This is not optimal
because it prevents Ninja from reporting an error when an input to a
rule really is missing. A better approach is to allow projects to
explicitly specify the byproducts of their custom commands so that no
phony rules are needed for them. In order to work with the non-Ninja
generators, the byproducts must be known separately from the outputs.
Add a new "BYPRODUCTS" option to the add_custom_command and
add_custom_target commands to specify byproducts explicitly. Teach the
Ninja generator to specify byproducts as outputs of the custom commands.
In the case of POST_BUILD, PRE_LINK, and PRE_BUILD events on targets
that link, the byproducts must be specified as outputs of the link rule
that runs the commands. Activate 'restat' for such rules so that Ninja
knows it needs to check the byproducts, but not for link rules that have
no byproducts.
Teach the add_custom_command and add_custom_target commands a new
USES_TERMINAL option. Use it to tell the generator to give the command
direct access to the terminal if possible.
State explicitly that the PRE_LINK mode is not for targets created by
the add_custom_target command. The existing wording for PRE_BUILD being
treated as PRE_LINK by non-VS generators will now imply this restriction
for PRE_BUILD too.
Format the reStructuredText markup manually. Organize the command
options into a definition list. Use inline markup to cross-reference
related documents.
