Allow passing in CFLAGS(_EXTRA) #483
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By using ?= we only set the CFLAGS variable in case it doesn't already have a value. This means it is now possible for someone to control the way bdwgc is compiled by feeding in the CFLAGS variable whereas previously one had to modify the Makefile.direct file. Further, since we consider the CFLAGS a reasonable default, the primary means of injecting control flags is by setting CFLAGS_EXTRA, where we now also allow passing in a value and the stuff in Makefile.direct is appended to that input.
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Okay |
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I've modified your commit a bit using ?= for CFLAGS_EXTRA, as well as for CXXFLAGS and ABI_FLAGS. Will push it today. |
Issue #483 (bdwgc). By using ?= we only set the CFLAGS variable in case it doesn't already have a value. This means it is now possible for someone to control the way bdwgc is compiled by feeding in the CFLAGS variable whereas previously one had to modify the Makefile.direct file. Further, since we consider the CFLAGS a reasonable default, the primary means of injecting control flags is by setting CFLAGS_EXTRA, where we now also allow passing in a value and the stuff in Makefile.direct is appended to that input. Same for [AS_]ABI_FLAG and CXXFLAGS variables. * Makefile.direct (ABI_FLAG, AS_ABI_FLAG, CFLAGS_EXTRA, CFLAGS, CXXFLAGS): Assign value using operator "?=" instead of "=" one.
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Merged as f7cfa9d |
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Cool, thanks! =) |
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FreeBSD build failed: https://app.travis-ci.com/github/ivmai/bdwgc/jobs/586297033 |
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Without looking at any core or errors, I'm guessing it is setting CFLAGS which are now used? Guess test environment need to set whatever should be tested... |
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Strange but CFGLAGS are empty when passed to the compiler (cc). |
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Last good build (bbe9092) before the change: https://app.travis-ci.com/github/ivmai/bdwgc/jobs/584941687 |
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Before (success): After (fail): |
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It looks like as if CFLAGS="-O2 -pipe" is passed to make, but I don't understand why. |
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It looks like that the system defines default CFLAGS (probably in "/etc/portage/make.conf" as said in https://wiki.gentoo.org/wiki/GCC_optimization#What_are_CFLAGS_and_CXXFLAGS.3F). |
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I'm working on the fix, along with some more refactoring |
(fix of commit f7cfa9d) Issue #483 (bdwgc). Some hosts (e.g. FreeBSD ones) predefine CFLAGS variable (to e.g. -O2), thus the options required to build libgc (e.g. -I) should be appended to CFLAGS. If there is a need to alter the default macros added to CFLAGS in Makefile.direct, then the client should provide the full list of -D options in CFLAGS_DEFAULT_MACROS variable. * Makefile.direct (CFLAGS_FOR_PIC): Set to empty (if unset). * Makefile.direct (CFLAGS_DEFAULT_MACROS): New variable (move all -D options from CFLAGS) which could be customized by client. * Makefile.direct (CFLAGS): Add comment; split assignment into two steps (assign "-O" value first using "?=" operator, then append the remaining options using "+=" operator); use CFLAGS_DEFAULT_MACROS.
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Should be fixed now. The required -I and other options are appended to CFLAGS, From now on, if you need some custom -D passed to Makefile.direct, it is better to set CFLAGS_DEFAULT_MACROS. |
Issue #483 (bdwgc). * Makefile.direct (CC, CXX): Assign value using operator "?=" instead of "=" one.
(fix of commit f7cfa9d) Issue #483 (bdwgc). AIX Make seems not to recognize "?=" operator properly. The proposed workaround to duplicate all flags of CFLAGS to CXXFLAGS (appended to the user-supplied CXXFLAGS if any). * Makefile.direct (CXXFLAGS): Set to empty value (using "?="); append all flags of CFLAGS (i.e., expand CFLAGS manually).
By using ?= we only set the CFLAGS variable in case it doesn't already have a value. This means it is now possible for someone to control the way bdwgc is compiled by feeding in the CFLAGS variable whereas previously one had to modify the Makefile.direct file. Further, since we consider the CFLAGS a reasonable default, the primary means of injecting control flags is by setting CFLAGS_EXTRA, where we now also allow passing in a value and the stuff in Makefile.direct is appended to that input.
This is very useful for using bdwgc from another repo, like you can just mirror bdwgc and then compile by feeding in all the compilation options as environment variables rather than having to first write them to the Makefile.direct file, which can be rather tricky to do programmatically. The normal mode of working is probably to CFLAGS_EXTRA, since that gets merged with the CFLAGS in Makefile.direct, but it also allows to directly set CFLAGS, thus overriding the default value of CFLAGS for total control.