60 lines
3 KiB
Python
60 lines
3 KiB
Python
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# coding: utf-8
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##
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## CompileDB.py - SCons build: generate a compilation database for clangd
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##
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# Copyright (C)
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# 2026, Hermann Vosseler <Ichthyostega@web.de>
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#
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# **Lumiera** is free software; you can redistribute it and/or modify it
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# under the terms of the GNU General Public License as published by the
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# Free Software Foundation; either version 2 of the License, or (at your
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# option) any later version. See the file COPYING for further details.
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#####################################################################
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from SCons.Script import COMMAND_LINE_TARGETS
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def setup(env):
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""" Emit a *compilation database*, describing every compiler invocation of the
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complete build. This JSON file is the interface used by `clangd` and the other
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tools built on the Clang front-end, which need to reproduce the exact flags
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of a translation unit in order to parse it the way the build does.
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The actual work is performed by the `CompilationDatabase` builder, which SCons
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provides since 4.0: it installs an additional *emitter* on the object builders,
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capturing each command line while the dependency graph is constructed. Thus no
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compilation is involved -- `scons compiledb` takes about two seconds -- and the
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database always covers the *complete declared build*, not just the requested
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target, since the SConscript definitions are processed into a dependency tree
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on every invocation anyway.
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@return a dependency node, to be added to the `build` alias, or an empty list
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when the feature is switched off (in which case nothing at all is
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installed into the build environment).
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@note **must be invoked after** `Platform.configure(env)`. The emitter would
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otherwise also capture the `conftest_*` compilations performed by the
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configure checks, which then show up as bogus entries below '.sconf_temp'.
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This ordering constraint is why this module is a plain helper invoked
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from the 'SConstruct' -- like `Setup`, `Options` and `Platform` -- and
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not a SCons tool loaded from the `LumieraEnvironment` constructor.
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@remark the database is written into the (relocatable) target tree, while the
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'.clangd' configuration in the project root directs the language server
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there; consumers do not search 'target/' on their own.
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"""
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if not isActivated(env): return []
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env.Tool('compilation_db') # the builder provided by SCons
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env['COMPILATIONDB_USE_ABSPATH'] = True # make recorded content unambiguous
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compileDB = env.CompilationDatabase('$TARGDIR/compile_commands.json')
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env.Alias('compiledb', compileDB)
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return compileDB
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def isActivated(env):
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""" generation is opt-in through the (sticky) build option,
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but can also be requested for a single invocation by naming the target.
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"""
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return env['COMPILEDB'] or 'compiledb' in COMMAND_LINE_TARGETS
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