Target Element (MSBuild)
Inputs: Optional attribute.
The files that form inputs into this target. Multiple files are separated by semicolons. The timestamps of the files will be compared with the timestamps of files in Outputs to determine whether the Target is up to date. For more information, see Incremental Builds, How to: Build Incrementally, and Transforms.
QUESTION
What happens if there's a file that's in Inputs that doesn't actually exist?
Will the target be considered out-of-date?
The current beavhior is that incremental targets are built when inputs are missing. That is, the target will be considered out-of date when a file in the inputs list cannot be found.
This behavior is implemented in TargetUpToDateChecker and produces log messages like:
Building target "Build" completely.
Input file "input1.txt" does not exist.
Note that while missing files cause rebuilds, changing the files of input elements doesn't matter - e.g. when the first build has Inputs="a.txt;b.txt" and the second build has Input="a.txt", the target is still up-to-date. This can happen in situations where the input list is filled by items created using patterns (e.g. <Foo Include="*.txt" /> items and Input="#(Foo)").
Related
Imagine a code generator which reads an input file (say a UML class diagram) and produces an arbitrary number of source files which I want to be handled in my project. (to draw a simple picture let's assume the code generator just produces .cpp files).
The problem is now the number of files generated depends on the input file and thus is not known when writing the CMakeLists.txt file or even in CMakes configure step. E.g.:
>>> code-gen uml.xml
generate class1.cpp..
generate class2.cpp..
generate class3.cpp..
What's the recommended way to handle generated files in such a case? You could use FILE(GLOB.. ) to collect the file names after running code-gen the first time but this is discouraged because CMake would not know any files on the first run and later it would not recognize when the number of files changes.
I could think of some approaches but I don't know if CMake covers them, e.g.:
(somehow) define a dependency from an input file (uml.xml in my example) to a variable (list with generated file names)
in case the code generator can be convinced to tell which files it generates the output of code-gen could be used to create a list of input file names. (would lead to similar problems but at least I would not have to use GLOB which might collect old files)
just define a custom target which runs the code generator and handles the output files without CMake (don't like this option)
Update: This question targets a similar problem but just asks how to glob generated files which does not address how to re-configure when the input file changes.
Together with Tsyvarev's answer and some more googling I came up with the following CMakeList.txt which does what I want:
project(generated)
cmake_minimum_required(VERSION 3.6)
set(IN_FILE "${CMAKE_SOURCE_DIR}/input.txt")
set_property(DIRECTORY APPEND PROPERTY CMAKE_CONFIGURE_DEPENDS "${IN_FILE}")
execute_process(
COMMAND python3 "${CMAKE_SOURCE_DIR}/code-gen" "${IN_FILE}"
WORKING_DIRECTORY ${PROJECT_BINARY_DIR}
INPUT_FILE "${IN_FILE}"
OUTPUT_VARIABLE GENERATED_FILES
OUTPUT_STRIP_TRAILING_WHITESPACE
)
add_executable(generated main.cpp ${GENERATED_FILES})
It turns an input file (input.txt) into output files using code-gen and compiles them.
execute_process is being executed in the configure step and the set_property() command makes sure CMake is being re-run when the input file changes.
Note: in this example the code-generator must print a CMake-friendly list on stdout which is nice if you can modify the code generator. FILE(GLOB..) would do the trick too but this would for sure lead to problems (e.g. old generated files being compiled, too, colleagues complaining about your code etc.)
PS: I don't like to answer my own questions - If you come up with a nicer or cleaner solution in the next couple of days I'll take yours!
What options do Bazel provide for creating new or extending existing targets that call C/C++-code checkers such as
qac
cppcheck
iwyu
?
Do I need to use a genrule or is there some other target rule for that?
Is https://bazel.build/versions/master/docs/be/extra-actions.html my only viable choice here?
In security critical software industries, such as aviation and automotive, it's very common to use the results of these calls to collect so called "metric reports".
In these cases, calls to such linters must have outputs that are further processed by the build actions of these metric report collectors. In such cases, I cannot find a useful way of reusing Bazel's "extra-actions". Ideas any one?
I've written something which uses extra actions to generate a compile_commands.json file used by clang-tidy and other tools, and I'd like to do the same kind of thing for iwyu when I get around to it. I haven't used those other tools, but I assume they fit the same pattern too.
The basic idea is to run an extra action which generates some output for each file (aka C/C++ compilation command), and then find all the output files afterwards (outside of Bazel) and aggregate them. A reasonably complete example is here for reference. Basically, the action listener (written in Python) decodes the extra action proto and extracts the source files, compiler options, etc:
action = extra_actions_base_pb2.ExtraActionInfo()
with open(argv[1], 'rb') as f:
action.MergeFromString(f.read())
cpp_compile_info = action.Extensions[extra_actions_base_pb2.CppCompileInfo.cpp_compile_info]
compiler = cpp_compile_info.tool
options = ' '.join(cpp_compile_info.compiler_option)
source = cpp_compile_info.source_file
output = cpp_compile_info.output_file
print('%s %s -c %s -o %s' % (compiler, options, source, output))
If you give the extra action an output template, then it can write that output to a file. If you give the output files distinctive names, you can find them all in the output tree and merge them together however you want.
A more sophisticated option is to use bazel query --output=proto and write code to calculate the extra action output filenames of the targets you're interested in from there. That requires writing more code, but you don't have problems with old output files in the output tree that are accidentally included when aggregating.
FWIW, Aspects are another possibility. However, I think extra actions work acceptably for this.
The CopiedFiles parameter is returning all the files that were intended to be copied. But given the fact that SkipUnchangedFiles is set to true and ttask itself is not copying anything as can be seen on command line (no copying message). Why not, then, CopiedFiles is empty?
I need to have CopiedFiles parameter be populated only with files that were actually copied (because they were changed) in order to further copy these files into some other folder. This is to maintain an up-to-date release folder as well as to extract only those files which actually need to be propogated onto UAT/production server.
For reference sake, the copy task code I'm using is given below:
<Copy SkipUnchangedFiles="true"
SourceFiles="#(cfile)"
DestinationFiles="#(cfile->'$(PublishDir)\%(Identity)')">
<Output
TaskParameter="CopiedFiles"
ItemName="Changed" />
</Copy>
<Message Text="changed:#(Changed)" Importance="high" />
Is there a bug in the copy task or this is the intended behavior.
The behavior you are seeing is by design. MSBuild keeps track of file dependencies using task outputs. If it were to do otherwise, anything that relied on the #(Changed) item array as an input would not fully process all of the files it needed in most cases. It will even keep track of properties and items created within targets that don't even execute when Inputs and Outputs are up-to-date, for the same reason. Consider making a different Copy task of your own with an additional output parameter, CopiedFilesCopiedByTask (this naming mirrors the naming and behavior of the ValueSetByTask in the otherwise defunct CreateProperty task).
The Story So Far
I've got a nice solution with a desktop application project, a few library projects, and a couple of development tools projects (also desktop applications). At the moment, my build server outputs all of the code into one OutputPath. So we end up with
drop-x.y.z\
Company.MainApplication.exe <-- main application
Company.MainApplicationCore.dll <-- libraries
Helper.exe <-- developer tools
Grapher.exe
Parser.exe
... <-- the rest of the output
But, we're growing up and people outside of our team want access to our tools. So I want to organize the output. I decided that what we would want is a different OutputPath per executable project
drop-x.y.z\
Company.MainApplication\
Company.MainApplication.exe <-- main application
Company.MainApplicationCore.dll <-- libraries
... <-- application specific output
Helper\
Helper.exe <-- developer tools
... <-- tool specific output
Grapher\
Grapher.exe
...
Parser\
Parser.exe
...
What I Did
I found this simple command. I like it because it retains all the Solution working-dir context that makes msbuild a pain.
msbuild /target:<ProjectName>
For example, from my solution root as a working directory, I would call
PS> msbuild /target:Helper /property:OutputPath="$pwd\out\Helper"
I'm testing this from PowerShell, so that $pwd resolves to the full path to my working directory, or the Solution root in this case. I get the output I desire.
However, when I run this command
PS> msbuild /target:Company.MainApplication /property:OutputPath="$pwd\out\Company.MainApplication"
I get the following error output (there's no more information, I ran with /verbosity:diagnostic)
The target "Company.MainApplication" does not exist in the project.
What I Need
The command fails on any project with a dot or dots in the name. I tried with many combinations of working directories and properties. I tried several ways of escaping the property values. I also tried running the command from a <Task> in a targets file.
I need to know either
A) How to fix this command to work property
B) How to achieve the same output with minimal friction
Try using an underscore as an escape character for the dot in the target parameter, e.g.
msbuild /target:Company_MainApplication /property:OutputPath="$pwd\out\Company.MainApplication"
Specify the target after the -target: switch in the format :. If the project name contains any of the characters %, $, #, ;, ., (, ), or ', replace them with an _ in the specified target name.
https://learn.microsoft.com/en-us/visualstudio/msbuild/how-to-build-specific-targets-in-solutions-by-using-msbuild-exe?view=vs-2019
Dan Nolan's answer and comments are correct. Just want to supplement the Microsoft documentation.
The /targets: switch is to identify a <Target to run in the project file. You need to supply your .csproj file as a an argument that is not prefixed by a /xx option marker.
You might also want to work based on the .sln file. In that case, you still dont specify the project in the .sln to build in this manner. I'll leave you to search up the correct syntax in case that's what you end up doing.
I was wondering if there was a way (such as a commad) to move a directory filled with, say, image files, to the build directory using cmake 2.8.
Thanks in advance!
The file() command can do what you want.
From the cmake manual:
The file() command also provides COPY and INSTALL signatures:
file(<COPY|INSTALL> files... DESTINATION <dir>
[FILE_PERMISSIONS permissions...]
[DIRECTORY_PERMISSIONS permissions...]
[NO_SOURCE_PERMISSIONS] [USE_SOURCE_PERMISSIONS]
[FILES_MATCHING]
[[PATTERN <pattern> | REGEX <regex>]
[EXCLUDE] [PERMISSIONS permissions...]] [...])
The COPY signature copies files, directories, and symlinks to a destination fold Relative input paths are evaluated with respect to the current source directory, and a relative destination is evaluated with respect to the current build directory. Copying preserves input file timestamps, and optimizes out a file if it exists at the destination with the same timestamp. Copying preserves input permissions unless explicit permissions or NO_SOURCE_PERMISSIONS are given (default is USE_SOURCE_PERMISSIONS). See the install(DIRECTORY) command for documentation of permissions, PATTERN, REGEX, and EXCLUDE options.
So you would have something like (tested):
file(COPY ${YOUR_SRC_IMAGE_DIR} DESTINATION ${CMAKE_CURRENT_BINARY_DIR}/YourPreferedDestination)
To move, you can use the RENAME form:
file(RENAME ${YOUR_SRC_IMAGE_DIR} ${CMAKE_CURRENT_BINARY_DIR}/PreferedDestination)
But I am not sure that you would want that, because the source will not be available anymore to reproduce the build sequence, hence my attempt to answer with the copy command above.