1
0
Fork 0
mirror of https://github.com/zephyrproject-rtos/esp-idf.git synced 2024-06-19 00:45:15 +02:00

build system: Document --warn-undefined-variables and add a config item for it

This commit is contained in:
Angus Gratton 2017-09-05 16:10:00 +10:00 committed by Angus Gratton
parent 8670844acf
commit 5f3cb9f9dc
4 changed files with 39 additions and 3 deletions

14
Kconfig
View file

@ -19,7 +19,19 @@ config PYTHON
help
The executable name/path that is used to run python. On some systems Python 2.x
may need to be invoked as python2.
endmenu
config MAKE_WARN_UNDEFINED_VARIABLES
bool "'make' warns on undefined variables"
default "y"
help
Adds --warn-undefined-variables to MAKEFLAGS. This causes make to
print a warning any time an undefined variable is referenced.
This option helps find places where a variable reference is misspelled
or otherwise missing, but it can be unwanted if you have Makefiles which
depend on undefined variables expanding to an empty string.
endmenu # SDK tool configuration
source "$COMPONENT_KCONFIGS_PROJBUILD"

View file

@ -351,6 +351,17 @@ Some tips for debugging the esp-idf build system:
For more debugging tips and general make information, see the `GNU Make Manual`.
.. _warn-undefined-variables:
Warning On Undefined Variables
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
By default, the build process will print a warning if an undefined variable is referenced (like ``$(DOES_NOT_EXIST)``). This can be useful to find errors in variable names.
If you don't want this behaviour, it can be disabled by disabling :ref:`CONFIG_MAKE_WARN_UNDEFINED_VARIABLES`.
Note that this option doesn't trigger a warning if ``ifdef`` or ``ifndef`` are used in Makefiles.
Overriding Parts of the Project
-------------------------------

View file

@ -25,4 +25,13 @@ By convention, all option names are upper case with underscores. When Kconfig ge
.. include:: /_build/inc/kconfig.inc
.. _Kconfig: https://www.kernel.org/doc/Documentation/kbuild/kconfig-language.txt
Customisations
==============
Because IDF builds by default with :ref:`warn-undefined-variables`, when the Kconfig tool generates Makefiles (the ``auto.conf`` file) its behaviour has been customised. In normal Kconfig, a variable which is set to "no" is undefined. In IDF's version of Kconfig, this variable is defined in the Makefile but has an empty value.
(Note that ``ifdef`` and ``ifndef`` can still be used in Makefiles, because they test if a variable is defined *and has a non-empty value*.)
When generating header files for C & C++, the behaviour is not customised - so ``#ifdef`` can be used to test if a boolean config item is set or not.
.. _Kconfig: https://www.kernel.org/doc/Documentation/kbuild/kconfig-language.txt

View file

@ -27,9 +27,13 @@ details := @echo
else
summary := @echo
details := @true
endif
# disable echoing of commands, directory names
MAKEFLAGS += --silent --warn-undefined-variables
MAKEFLAGS += --silent
ifdef CONFIG_MAKE_WARN_UNDEFINED_VARIABLES
MAKEFLAGS += --warn-undefined-variables
endif
# General make utilities