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| -rw-r--r-- | NEWS | 127 |
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@@ -1,3 +1,130 @@ +Version 0.15.0 + + * Support for dynamic dependencies in ad hoc recipes. + + Specifically, the `depdb` builtin now has the new `dyndep` command that + can be used to extract dynamic dependencies from program output or a + file. For example, from program output: + + obje{hello.o}: cxx{hello} + {{ + s = $path($<[0]) + o = $path($>) + + poptions = $cxx.poptions $cc.poptions + coptions = $cc.coptions $cxx.coptions + + depdb dyndep $poptions --what=header --default-type=h -- \ + $cxx.path $poptions $coptions $cxx.mode -M -MG $s + + diag c++ ($<[0]) + + $cxx.path $poptions $coptions $cxx.mode -o $o -c $s + }} + + Or, alternatively, from a file: + + t = $(o).t + depdb dyndep $poptions --what=header --default-type=h --file $t -- \ + $cxx.path $poptions $coptions $cxx.mode -M -MG $s >$t + + The above depdb-dyndep commands will run the C++ compiler with the -M -MG + options to extract the header dependency information, parse the resulting + make dependency declaration (either from stdout or from file) and enter + each header as a prerequisite of the obje{hello.o} target, as if they were + listed explicitly. It will also save this list of headers in the auxiliary + dependency database (hello.o.d file) in order to detect changes to these + headers on subsequent updates. The --what option specifies what to call + the dependencies being extracted in diagnostics. The --default-type option + specifies the default target type to use for a dependency if its file name + cannot be mapped to a target type. + + The above depdb-dyndep variant extracts the dependencies ahead of the + compilation proper and will handle auto-generated headers (see the -MG + option for details) provided we pass the header search paths where they + could be generated with the -I options (passed as $poptions in the above + example). + + If there can be no auto-generated dependencies or if they can all be + listed explicitly as static prerequisites, then we can use a variant of + the depdb-dyndep command that extracts the dependencies as a by-product of + compilation. In this mode only the --file input is supported. For example + (assuming hxx{config} is auto-generated): + + obje{hello.o}: cxx{hello} hxx{config} + {{ + s = $path($<[0]) + o = $path($>) + t = $(o).t + + poptions = $cxx.poptions $cc.poptions + coptions = $cc.coptions $cxx.coptions + + depdb dyndep --byproduct --what=header --default-type=h --file $t + + diag c++ ($<[0]) + + $cxx.path $poptions $coptions $cxx.mode -MD -MF $t -o $o -c $s + }} + + Other options supported by the depdb-dyndep command: + + --format <name> + + Dependency format. Currently only the `make` dependency format is + supported and is the default. + + --cwd <dir> + + Working directory used to complete relative dependency paths. This + option is currently only valid in the --byproduct mode (in the normal + mode relative paths indicate non-existent files). + + --drop-cycles + + Drop prerequisites that are also targets. Only use this option if you + are sure such cycles are harmless, that is, the output is not affected + by such prerequisites' content. + + --update-{include,exclude} <tgt>|<pat> + + Prerequisite targets/patterns to include/exclude (from the static + prerequisite set) for update during match (those excluded will be + updated during execute). The order in which these options are specified + is significant with the first target/pattern that matches determining + the result. If only the --update-include options are specified, then + only the explicitly included prerequisites will be updated. Otherwise, + all prerequisites that are not explicitly excluded will be updated. If + none of these options is specified, then all the static prerequisites + are updated during match. Note also that these options do not apply to + ad hoc prerequisites which are always updated during match. + + The common use-case for the --update-exclude option is to omit updating + a library which is only needed to extract exported preprocessor options. + Here is a typical pattern: + + import libs = libhello%lib{hello} + + libue{hello-meta}: $libs + + obje{hello.o}: cxx{hello} libue{hello-meta} + {{ + s = $path($<[0]) + o = $path($>) + + poptions = $cxx.poptions $cc.poptions + poptions += $cxx.lib_poptions(libue{hello-meta}, obje) + coptions = $cc.coptions $cxx.coptions + + depdb dyndep $poptions --what=header --default-type=h \ + --update-exclude libue{hello-meta} -- \ + $cxx.path $poptions $coptions $cxx.mode -M -MG $s + + diag c++ ($<[0]) + + $cxx.path $poptions $coptions $cxx.mode -o $o -c $s + }} + Version 0.14.0 * Support for hermetic build configurations. |