build: actually set LDFLAGS/LIBS & stop overriding CFLAGS/LDFLAGS #5504
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Currently, only EXTRA_CFLAGS and EXTRA_LDFLAGS are printed. See also the variables defined on config.mk.in.
Both variables are used inside on src/prog.mk and src/so.mk, but they are not currently defined in any makefile, so their values cannot be substituted by ./configure. This means that the variables can be set when running make (such as with `make LDFLAGS=-Lfoo`), but changing them in configure.ac has no effect. The same applies when trying to set them when running ./configure (such as with `./configure LDFLAGS=-Lfoo`).
LIBS is the variable that Autoconf uses to put library flags. From the
manual of GNU Autoconf (version 2.69):
> -- Variable: LDFLAGS
>
> [...]
>
> This variable's contents should contain options like '-s' and '-L'
> that affect only the behavior of the linker. Please see the
> explanation of 'CFLAGS' for what you can do if an option also
> affects other phases of the compiler.
>
> Don't use this variable to pass library names ('-l') to the linker;
> use 'LIBS' instead.
>
> -- Variable: LIBS
>
> '-l' options to pass to the linker. The default value is empty,
> but some Autoconf macros may prepend extra libraries to this
> variable if those libraries are found and provide necessary
> functions, see *note Libraries::. 'configure' uses this variable
> when linking programs to test for C, C++, Objective C, Objective
> C++, Fortran, and Go features.
|
Reproducing the last commit message here as these details might not be commonly makefiles: stop overriding CFLAGS/LDFLAGS From the manual of GNU Automake (version 1.16.5)[1] [2]:
See also the description of CFLAGS in the GNU Autoconf manual[3]. Note: We do not use automake (save for aclocal) nor generally follow the [1] https://www.gnu.org/software/automake/manual/1.16.5/html_node/User-Variables.html |
From the manual of GNU Automake (version 1.16.5)[1] [2]: > 3.6 Variables reserved for the user > > Some `Makefile` variables are reserved by the GNU Coding Standards for > the use of the "user"—the person building the package. For instance, > `CFLAGS` is one such variable. > > Sometimes package developers are tempted to set user variables such > as `CFLAGS` because it appears to make their job easier. However, the > package itself should never set a user variable, particularly not to > include switches that are required for proper compilation of the > package. Since these variables are documented as being for the > package builder, that person rightfully expects to be able to override > any of these variables at build time. > > To get around this problem, Automake introduces an > automake-specific shadow variable for each user flag variable. > (Shadow variables are not introduced for variables like `CC`, where > they would make no sense.) The shadow variable is named by prepending > `AM_` to the user variable's name. For instance, the shadow variable > for `YFLAGS` is `AM_YFLAGS`. The package maintainer—that is, the > author(s) of the `Makefile.am` and `configure.ac` files—may adjust > these shadow variables however necessary. > > Note Flag Variables Ordering::, for more discussion about these > variables and how they interact with per-target variables. See also the description of CFLAGS in the GNU Autoconf manual[3]. Note: We do not use automake (save for aclocal) nor generally follow the GNU Coding Standards, but the concept still applies. Also, the closest analogous in the project to the `AM_` prefix would currently likely be `EXTRA_`. [1] https://www.gnu.org/software/automake/manual/1.16.5/html_node/User-Variables.html [2] https://www.gnu.org/software/automake/manual/1.16.5/html_node/Flag-Variables-Ordering.html [3] https://www.gnu.org/software/autoconf/manual/autoconf-2.69/html_node/Preset-Output-Variables.html
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Force-pushed to remove commit e7be30a ("makefiles: set It technically changes the behavior in more ways than intended (depending on |
With this, CFLAGS and CPPFLAGS are used when compiling and LDFLAGS when
linking, just like in the built-in GNU make rules. From `make -p`:
COMPILE.c = $(CC) $(CFLAGS) $(CPPFLAGS) $(TARGET_ARCH) -c
LINK.c = $(CC) $(CFLAGS) $(CPPFLAGS) $(LDFLAGS) $(TARGET_ARCH)
LINK.o = $(CC) $(LDFLAGS) $(TARGET_ARCH)
Note: It is unclear where the `INCLUDE` variable comes from; it is not
documented in autoconf nor GNU make and automake (which itself is not
used in this repository) only mentions `INCLUDES`:
`INCLUDES`
This does the same job as `AM_CPPFLAGS` (or any per-target
`_CPPFLAGS` variable if it is used). It is an older name for
the same functionality. This variable is deprecated; we
suggest using `AM_CPPFLAGS` and per-target `_CPPFLAGS` instead.
Environment: automake 1.16.5-2 and GNU make 4.4.1 on Artix Linux.
See also commit 671c3f2 ("build: actually set LDFLAGS and LIBS in
makefiles", 2022-11-30) / PR netblue30#5504.
With this, CFLAGS and CPPFLAGS are used when compiling and LDFLAGS when
linking, just like in the built-in GNU make rules. From `make -p`:
COMPILE.c = $(CC) $(CFLAGS) $(CPPFLAGS) $(TARGET_ARCH) -c
LINK.c = $(CC) $(CFLAGS) $(CPPFLAGS) $(LDFLAGS) $(TARGET_ARCH)
LINK.o = $(CC) $(LDFLAGS) $(TARGET_ARCH)
Note: It is unclear where the `INCLUDE` variable comes from; it is not
documented in autoconf nor GNU make and automake (which itself is not
used in this repository) only mentions `INCLUDES`:
`INCLUDES`
This does the same job as `AM_CPPFLAGS` (or any per-target
`_CPPFLAGS` variable if it is used). It is an older name for
the same functionality. This variable is deprecated; we
suggest using `AM_CPPFLAGS` and per-target `_CPPFLAGS` instead.
Environment: automake 1.16.5-2 and GNU make 4.4.1 on Artix Linux.
See also commit 671c3f2 ("build: actually set LDFLAGS and LIBS in
makefiles", 2022-11-30) / PR netblue30#5504.
With this, CFLAGS and CPPFLAGS are used when compiling and LDFLAGS when
linking, just like in the built-in GNU make rules. From `make -p`:
COMPILE.c = $(CC) $(CFLAGS) $(CPPFLAGS) $(TARGET_ARCH) -c
LINK.c = $(CC) $(CFLAGS) $(CPPFLAGS) $(LDFLAGS) $(TARGET_ARCH)
LINK.o = $(CC) $(LDFLAGS) $(TARGET_ARCH)
Note: It is unclear where the `INCLUDE` variable comes from; it is not
documented in autoconf nor GNU make and automake (which itself is not
used in this repository) only mentions `INCLUDES`:
`INCLUDES`
This does the same job as `AM_CPPFLAGS` (or any per-target
`_CPPFLAGS` variable if it is used). It is an older name for
the same functionality. This variable is deprecated; we
suggest using `AM_CPPFLAGS` and per-target `_CPPFLAGS` instead.
Environment: automake 1.16.5-2 and GNU make 4.4.1 on Artix Linux.
See also commit 671c3f2 ("build: actually set LDFLAGS and LIBS in
makefiles", 2022-11-30) / PR netblue30#5504.
Commits:
This is a follow-up to #5478 and #5488.