mirror of
https://github.com/mozilla/gecko-dev.git
synced 2024-11-29 15:52:07 +00:00
65 lines
2.7 KiB
Plaintext
65 lines
2.7 KiB
Plaintext
INTRODUCTION
|
|
|
|
make.py (and the pymake modules that support it) are an implementation of the make tool
|
|
which are mostly compatible with makefiles written for GNU make.
|
|
|
|
PURPOSE
|
|
|
|
The Mozilla project inspired this tool with several goals:
|
|
|
|
* Improve build speeds, especially on Windows. This can be done by reducing the total number
|
|
of processes that are launched, especially MSYS shell processes which are expensive.
|
|
|
|
* Allow writing some complicated build logic directly in Python instead of in shell.
|
|
|
|
* Allow computing dependencies for special targets, such as members within ZIP files.
|
|
|
|
* Enable experiments with build system. By writing a makefile parser, we can experiment
|
|
with converting in-tree makefiles to another build system, such as SCons, waf, ant, ...insert
|
|
your favorite build tool here. Or we could experiment along the lines of makepp, keeping
|
|
our existing makefiles, but change the engine to build a global dependency graph.
|
|
|
|
KNOWN INCOMPATIBILITIES
|
|
|
|
* Order-only prerequisites are not yet supported
|
|
|
|
* Secondary expansion is not yet supported.
|
|
|
|
* Target-specific variables behave differently than in GNU make: in pymake, the target-specific
|
|
variable only applies to the specific target that is mentioned, and does not apply recursively
|
|
to all dependencies which are remade. This is an intentional change: the behavior of GNU make
|
|
is neither deterministic nor intuitive.
|
|
|
|
* $(eval) is only supported during the parse phase. Any attempt to recursively expand
|
|
an $(eval) function during command execution will fail. This is an intentional incompatibility.
|
|
|
|
* There is a subtle difference in execution order that can cause unexpected changes in the
|
|
following circumstance:
|
|
** A file `foo.c` exists on the VPATH
|
|
** A rule for `foo.c` exists with a dependency on `tool` and no commands
|
|
** `tool` is remade for some other reason earlier in the file
|
|
In this case, pymake resets the VPATH of `foo.c`, while GNU make does not. This shouldn't
|
|
happen in the real world, since a target found on the VPATH without commands is silly. But
|
|
mozilla/js/src happens to have a rule, which I'm patching.
|
|
|
|
* pymake does not implement any of the builtin implicit rules or the related variables. Mozilla
|
|
only cares because pymake doesn't implicitly define $(RM), which I'm also fixing in the Mozilla
|
|
code.
|
|
|
|
ISSUES
|
|
|
|
* Speed is a problem.
|
|
|
|
FUTURE WORK
|
|
|
|
* implement a new type of command which is implemented in python. This would allow us
|
|
to replace the current `nsinstall` binary (and execution costs for the shell and binary) with an
|
|
in-process python solution.
|
|
|
|
AUTHOR
|
|
|
|
Initial code was written by Benjamin Smedberg <benjamin@smedbergs.us>. For future releases see
|
|
http://benjamin.smedbergs.us/pymake/
|
|
|
|
See the LICENSE file for license information (MIT license)
|