New Wrap: Kafel #1917
New Wrap: Kafel #1917
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| run_command(flex, '--outfile=lexer.c', 'src/lexer.l', check: true) | ||
| run_command(bison, '-o=parser.c', 'src/parser.y', check: true) |
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You don't want to use run_command for this, this is what custom_target is for:
lexer = custom_target(
command : [flex, '--outfile=@OUTPUT0@', '--header-file=@OUTPUT1@', '@INPUT@'],
input : 'src/lexer.l',
output : ['@[email protected]', '@[email protected]'],
)
parser = custom_target(
command : [bison, '-o', '@OUTPUT0@', '--defines=@OUTPUT1@', '@INPUT@'],
input : 'src/parser.y',
output : ['@[email protected]', '@[email protected]'],
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So, I had already tried it that way, but it didn't work, so I resorted to using run_command. Many people who use flex and bison seem to face the same issue and end up resorting to this method.
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With this method it simply does not generate the .c files.
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It won’t generate the c file if you don’t add the parser variable to the target, because custom targets are not built by default.
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I am adding it, and it still doesn't work.
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Here's an example of how to do it: https://github.com/dcbaker/meson-plus-plus/blob/main/src/frontend/meson.build
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So, I had already tried using custom_target before, but without success. It fails to generate the files at the exact moment they are needed, resulting in file not found errors. I attempted to fix this but was unable to resolve the issue.
However, after researching, I found an approach using run_command, which is used in similar contexts to mine.
Some examples:
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Neither of those projects are doing the right thing. There are two problems with the run_target approach you're taking,
- it writes files into the source directory. Meson generally promises not to do this, because it causes issues, many cmake projects specifically go out of their way to turn off in-tree builds
- the flex and bison files get written at configure time instead of build time, which means that their inputs are not properly tracked (so among other things ninja clean cant erase them), and to regenerate them a user needs to manually re-run meson, since Meson doesn't know those command write files
The critical thing here is that the output of the assigned variable from the custom_target needs to be in the sources list of the target that requires it:
x = custom_target(...)
library(
'foo',
'foo.c', 'lib..c', x,
)That is how Meson knows that libfoo depends on the output of x, and properly orders it so that x is generated before any files in libfoo start compiling. the Meson++ example I pointed you to demonstrates how to write this as a custom_target, which is the right way to do this.
run_target isn't for codegen, it's for things like running linters or code formatters.
| 'lexer.c', | ||
| 'parser.c' |
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Then you'll want to use the parser and lexer variables instead of these.
| kafel_lib = library('kafel', | ||
| sources: kafel_sources, | ||
| include_directories: kafel_inc, | ||
| install: true |
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gnu_symbol_visibility : 'hidden',
soversion : 1,is also needed to match the makefile.
You'll need to double check that soversion though, and make sure it matches the makefile.
| name : 'kafel', | ||
| description : 'Kafel - seccomp filter generator', | ||
| version : meson.project_version(), | ||
| filebase : 'kafel', | ||
| subdirs : 'kafel', | ||
| libraries : kafel_lib |
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you can pass kafel_lib as a positional argument here, which will eliminate some of the need to repeat yourself, at least name, filebase, and libraries can be dropped if you do that.
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