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Diffstat (limited to 'doc')
| -rw-r--r-- | doc/manual.cli | 328 |
1 files changed, 319 insertions, 9 deletions
diff --git a/doc/manual.cli b/doc/manual.cli index 07d816a..03fa04a 100644 --- a/doc/manual.cli +++ b/doc/manual.cli @@ -2093,7 +2093,7 @@ If we forget to adjust the \c{missing-name} test, then this is what we could expect to see when running the tests: \ -b test +$ b test c++ hello/cxx{hello} -> hello/obje{hello} ld hello/exe{hello} test hello/exe{hello} + hello/testscript{testscript} @@ -6700,8 +6700,8 @@ quickly re-run a previously failed test), it can also be persisted in subset of tests by default. For example: \ -b test config.test=foo/exe{driver} # Only test foo/exe{driver} target. -b test config.test=bar/baz # Only run bar/baz testscript test. +$ b test config.test=foo/exe{driver} # Only test foo/exe{driver} target. +$ b test config.test=bar/baz # Only run bar/baz testscript test. \ The \c{config.test} variable contains a list of \c{@}-separated pairs with the @@ -6712,14 +6712,14 @@ name. Otherwise \- an id path. The targets are resolved relative to the root scope where the \c{config.test} value is set. For example: \ -b test config.test=foo/exe{driver}@bar +$ b test config.test=foo/exe{driver}@bar \ To specify multiple id paths for the same target we can use the pair generation syntax: \ -b test config.test=foo/exe{driver}@{bar baz} +$ b test config.test=foo/exe{driver}@{bar baz} \ If no targets are specified (only id paths), then all the targets are tested @@ -6741,9 +6741,9 @@ and the right hand side \- for individual tests. The zero value clears the previously set timeout. For example: \ -b test config.test.timeout=20 # Test operation. -b test config.test.timeout=20/5 # Test operation and individual tests. -b test config.test.timeout=/5 # Individual tests. +$ b test config.test.timeout=20 # Test operation. +$ b test config.test.timeout=20/5 # Test operation and individual tests. +$ b test config.test.timeout=/5 # Individual tests. \ The test timeout can be specified on multiple nested root scopes. For example, @@ -6759,7 +6759,7 @@ specifying the \c{config.test.runner} variable. Its value has the \c{<path> [<options>]} form. For example: \ -b test config.test.runner=\"valgrind -q\" +$ b test config.test.runner=\"valgrind -q\" \ When the runner program is specified, commands of simple and Testscript tests @@ -7648,6 +7648,12 @@ config.cc.reprocess cc.reprocess config.cc.pkgconfig.sysroot + +config.cc.compiledb +config.cc.compiledb.name +config.cc.compiledb.filter +config.cc.compiledb.filter.input +config.cc.compiledb.filter.output \ Note that the compiler mode options are \"cross-hinted\" between \c{config.c} @@ -8054,6 +8060,310 @@ As a result, it should only be used for dealing with issues in third-party installation} should be used instead.| +\h#cc-compiledb|Compilation Database| + +The \c{cc}-based modules provide support for generating and maintaining the +\l{https://clang.llvm.org/docs/JSONCompilationDatabase.html JSON Compilation +Database} which can be used by other tools (static analyzers, language +servers, IDEs, etc) to understand how a codebase is compiled. \"Maintaining\" +in the previous sentence means that if new source files get added to the +project or old ones removed, or if any compilation options change, then the +corresponding entries in the compilation database will be automatically +updated when you update your project. This helps maintain the database in sync +with the project state. + +The generation of compilation databases and their configuration are controlled +with a number of \c{config.cc.compiledb.*} variables. The +\c{config.cc.compiledb} variable provides a simplified interface that enables +the generation of one database per project with the resulting database +containing entries for all the source and object files. The rest of the +variables provide a more flexible interface that allows you to generate +multiple databases in different locations as well as filter the entries that +end up in each database. + +Let's start with the simplified interface as provided by +\c{config.cc.compiledb}. The value of this configuration variable is a single +\ci{name} or a \ci{name} and \ci{path} pair in the \c{\i{name}[@\i{path}]} +form. + +The \ci{name} part is the compilation database name that can be used to refer +to it in filters (see below). If \ci{path} is absent or is (syntactically) a +directory, then \ci{name} is also used to derive the compilation database file +by appending the \c{.json} extension to it. + +If \ci{path} is absent, then the compilation database is placed into the +top-level amalgamation that loads any \c{cc}-based module. Otherwise, the +database is placed into the specified location. + +The special \c{-} name is interpreted as an instruction to dump the database +to \c{stdout}. + +Let's see some examples of using \c{config.cc.compiledb} to handle a few +common scenarios. Here we will use \l{bdep(1)} to create amalgamations +(configurations) and configure (initialize) one or more projects. We will +assume we have \c{hello} and \c{libhello} as if created like this: + +\ +$ bdep new -t exe hello +$ bdep new -t lib libhello +\ + +The most common scenario is likely having a compilation database per +project: + +\ +$ cd libhello +$ bdep config create ../build-gcc @gcc cc config.cxx=g++ +$ bdep init @gcc config.cc.compiledb=libhello +$ cd .. + +$ cd hello +$ bdep config add ../build-gcc @gcc +$ bdep init @gcc config.cc.compiledb=hello +$ cd .. + +$ b hello/ libhello/ +\ + +\N|Or if you prefer to create/add configuration as part of \c{init} (notice +the \c{--} separator): + +\ +$ bdep init -C ../build-gcc @gcc cc config.cxx=g++ -- \\ + config.cc.compiledb=libhello + +$ bdep init -A ../build-gcc @gcc config.cc.compiledb=hello +\ + +| + +After the update (the last command), we will have \c{hello.json} and +\c{libhello.json} in \c{build-gcc/} which contain the compilation command +lines for each project. + +\N|Only source files that are compiled end up being added to the compilation +database. + +To illustrate this point, let's assume our \c{hello} project imports and links +\c{libhello}. And instead of updating both as in the above example, we will +first update only \c{hello}: + +\ +$ b hello/ +\ + +In this case \c{libhello.json} will still be generated but it will only +contain a subset of the expected entries \- only those that were caused to be +compiled by \c{hello}. The missing entries can be added by updating +\c{libhello}: + +\ +$ b libhello/ +\ + +| + +In the above setup it feels natural to call each database after the project +and place them into the output directory. However, some consumers, such as +IDEs, may not handle this setup well. Specifically, they may only recognize +the canonical \c{compile_commands.json} file as the compilation database, +opening all other files as generic JSON. They may also assume the directory +where this file resides to be the project source directory root. To accommodate +these assumptions we can instead place each database into the project's +source directory and call it \c{compile_commands.json}: + +\ +$ bdep init @gcc config.cc.compiledb=libhello@./compile_commands.json + +$ bdep init @gcc config.cc.compiledb=hello@./compile_commands.json +\ + +Note that in this case it will be your responsibility to remove the database +files if and when necessary. \N{\l{bdep-new(1)} adds \c{compile_commands.json} +to \c{.gitignore} it generates.} + +If instead of having a separate database for each project we wanted to place +all the entries into a single database, then the relevant commands would +change as follows: + +\ +$ bdep init @gcc config.cc.compiledb=compiledb + +$ bdep init @gcc config.cc.compiledb=compiledb +\ + +This would give us a single \c{build-gcc/compiledb.json} that contains the +compilation command lines for both projects. + +In the above example only \c{hello} and \c{libhello} will end up in the +database, but not any of their dependencies. What if we wanted entries for +everything in \c{build-gcc/}? In this case, we should enable the compilation +database for the entire configuration rather than for individual projects: + +\ +$ bdep config create ../build-gcc @gcc cc \\ + config.cxx=g++ \\ + config.cc.compiledb=compiledb +$ bdep init @gcc + +$ bdep config add ../build-gcc @gcc +$ bdep init @gcc +\ + +If multiple linked configurations are involved, then we would often want +projects initialized in different configurations share the compilation +database. The representative scenario here is a tool, such as a source code +generator, which is initialized in the host configuration, and its runtime +library plus tests/examples, which are initialized in the target +configuration. Let's assume that in our example \c{hello} is the tool and +\c{libhello} is the runtime library and both are part of the same project. +This is how we can arrange for them to share the compilation database: + +\ +$ bdep config create @host ../host-gcc --type host cc config.cxx=g++ +$ bdep config create @target ../build-gcc cc config.cxx=g++ + +$ bdep init @host -d hello config.cc.compiledb=hello@../build-gcc/ +$ bdep init @target -d libhello config.cc.compiledb=hello + +$ bdep update @host @target +\ + +With this setup the \c{hello.json} database in \c{build-gcc/} will contain +entries for both \c{hello} and \c{libhello}. + +If instead of configuring and maintaining the compilation database in a file +you want to dump it somewhere once, the recommended approach is to write it +to \c{stdout}. For example: + +\ +$ b -n hello/ libhello/ config.cc.compiledb=- >/tmp/compiledb.json +\ + +Note that writing to \c{stdout} forces recompilation of all the targets that +would be updated in order to make sure their entries end up in the database. +If you don't want the actual recompilation, then you can use the dry run mode +(\c{-n} option above). + +\N|If your projects are spread across multiple linked configurations and you +would like to get compilation command lines for all of them, then use the +global override for \c{config.cc.compiledb}: + +\ +$ b '!config.cc.compiledb=-' ... +\ + +As mentioned earlier, the entries that will end up in such a database are +determined by what gets updated.| + +Let's now turn to the rest of the \c{config.cc.compiledb.*} configuration +variables that provide a lower-level but more flexible interface. The +following listing shows their synopsis: + +\ +config.cc.compiledb.name = <name>[@<path>]... +config.cc.compiledb.filter = [<name>@]<bool>... +config.cc.compiledb.filter.input = [<name>@]<target-type>... +config.cc.compiledb.filter.output = [<name>@]<target-type>... +\ + +The \c{config.cc.compiledb.name} variable specifies the name and location of +one or more compilation databases. The semantics of the +\c{\i{name}[@\i{path}]} pair is the same as in \c{config.cc.compiledb} +discussed above, except that if \ci{path} is absent, then the database is +placed into the project being configured rather than into the top-level +amalgamation. + +Also, unlike \c{config.cc.compiledb}, this variable does not automatically +enable writing to the specified databases. Instead, this is the job of +\c{config.cc.compiledb.filter}. Splitting this logic into two steps allows us +to configure the database name/location in one place, typically an outer +amalgamation, and then enable writing to it in other places, typically +specific subprojects. + +The \c{config.cc.compiledb.filter.{input,output\}} variables allow us to +filter the entries that end up in the databases based on the input (\c{c{\}}, +\c{cxx{\}}, etc) and output (\c{obja{\}}, \c{objs{\}}, etc) target types. + +Note that in all three \c{.filter} variables the values are examined in the +reverse order and the first entry that matches determines the outcome. +Entries without \ci{name} apply to all databases and the target types are +matched taking into account inheritance (so \c{target{\}} will match any type) +and groups (so \c{obj{\}} will match any \c{obj[eas]{\}}). If no target type +filter (input or output) is specified, then no corresponding target filtering +is performed. + +\N|The \c{config.cc.compiledb=<name>} semantics can be expressed as the +following set of lower-level variables: + +\ +config.cc.compiledb.name = <name>@../path/to/amalgamation/ +config.cc.compiledb.filter += <name>@true +config.cc.compiledb.filter.input += <name>@target +config.cc.compiledb.filter.output += <name>@target +\ + +The last three assignments only apply if the corresponding variable is not set +to a custom value for this project.| + +Let's look at a few examples of using these lower-level configuration +variables. The common use for the output target filtering is getting rid of +\c{obja{\}} or \c{objs{\}} entries in libraries. Unless configured otherwise, +when we build a library we end up with both static and shared variants. And +this means that each source file for the library is compiled twice, once to +produce \c{obja{\}} that goes to the static library and once -- \c{objs{\}}. +And that, in turn, means that we will end up with two compilation database +entries for each such source file. If we don't want that for some reason (for +instance, because the consumer of the database does not handle this well), +then we can filter one of them out. For example, below is how we can +initialize \c{libhello} to achieve this (notice that we also include +\c{obje{\}} to keep object files for executables, such as tests): + +\ +$ bdep init @gcc \\ + config.cc.compiledb=libhello \\ + config.cc.compiledb.filter.output='obje objs' +\ + +As an example of the input target type filtering, below is how we can keep +entries only for the C and C++ source files, filtering out everything else +(assembler, Objective-C/C++), for instance, because the consumer of our +database does not recognize them: + +\ +$ bdep init @gcc \\ + config.cc.compiledb=libhello \\ + config.cc.compiledb.filter.input='c cxx' +\ + +As an example of a more advanced configuration, consider a compilation +database for a project that use C++ modules. To know how such a project is +compiled we not only need to know how its own source files are compiled, but +also how to compile all the module interfaces that it consumes, including from +other projects, transitively. One way to set this up would be to enable +writing entries of the \c{bmi{\}} output target type to any database in the +amalgamation: + +\ +$ bdep config create ../build-gcc @gcc cc \\ + config.cxx=g++ \\ + config.cc.compiledb.filter=true \\ + config.cc.compiledb.filter.output=bmi \\ + + +$ bdep init @gcc config.cc.compiledb=libhello + +$ bdep init @gcc config.cc.compiledb=hello +\ + +With this setup \c{libhello.json} and \c{hello.json} will contain module +interface entries from all the dependencies. + +\N|When debugging complex compilation database setups it can be helpful to +increase diagnostics verbosity to level 6 in order to get a trace of filtering +decisions (the relevant lines will contain the \c{compiledb} keyword).| + + \h#cc-gcc|GCC Compiler Toolchain| The GCC compiler id is \c{gcc}. |