Remove replacing -I with -isystem #1130
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Building OLA with a GCC 6 cross-toolchain fails:
```
/usr/bin/arm-linux-g++ -DHAVE_CONFIG_H -I. -D_LARGEFILE_SOURCE
-D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -I./include -I./include
-Wall -Wformat -W -isystem
/usr/arm-buildroot-linux-gnueabihf/sysroot/usr/include -pthread
-D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os
-pthread -c -o libs/acn/e131_transmit_test.o
libs/acn/e131_transmit_test.cpp
/usr/bin/arm-linux-g++ -DHAVE_CONFIG_H -I. -D_LARGEFILE_SOURCE
-D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -I./include -I./include
-Wall -Wformat -W -isystem
/usr/arm-buildroot-linux-gnueabihf/sysroot/usr/include -pthread
-D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -Os
-pthread -c -o libs/acn/E131TestFramework.o
libs/acn/E131TestFramework.cpp
In file included from
/opt/ext-toolchain/arm-buildroot-linux-gnueabihf/include/c++/6.1.0/ext/string_conversions.h:41:0,
from
/opt/ext-toolchain/arm-buildroot-linux-gnueabihf/include/c++/6.1.0/bits/basic_string.h:5402,
from
/opt/ext-toolchain/arm-buildroot-linux-gnueabihf/include/c++/6.1.0/string:52,
from ./tools/ola_trigger/config.ypp:2:
/opt/ext-toolchain/arm-buildroot-linux-gnueabihf/include/c++/6.1.0/cstdlib:75:25:
fatal error: stdlib.h: No such file or directory
#include_next <stdlib.h>
^
compilation terminated.
```
The C++ library in GCC 6 now provides its own `<stdlib.h>` header that
wraps the C library header of the same name, so in `<cstdlib>` the
header include
```
```
has become
```
```
`#include_next` is sensitive to the order of directories in the
preprocessor's search path, so if that order is changed with `-isystem`
then the compiler can't find the right header:
```
[1] /usr/arm-buildroot-linux-gnueabihf/sysroot/usr/include
[2] /opt/ext-toolchain/arm-buildroot-linux-gnueabihf/include/c++/6.1.0
[..]
End of search list.
```
`<cstdlib>` is located in [2] whereas `<stdlib.h>` (C library header) is
in [1]. In this case, the `#include_next <stdlib.h>` statement in
`<cstdlib>`, located in [2], is evaluated **after** the search path [1],
so the compiler does not find the right system header.
The problem is that the OLA build system replaces the `-I` in the CFLAGS
from libprotobuf with `-isystem` to fix some warnings treated as errors
in the libprotobuf header files.
`-isystem` should be used to suppress warnings in system headers only
and the libprotobuf header files are not system files.
The correct fix is to compile with less restrictions and remove
`-Werror` for the build.
As using `-isystem` is reordering GCCs search path and using `-isystem`
is really not necessary, remove the faulty replacement of `-I`.
Closes: #1125
|
Sorry @joerg-krause please can you target our 0.10 branch; 0.10.2 is just branched off and NEWS updated just before we release, where as 0.10 will get a branch that becomes 0.10.3. |
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Building OLA with a GCC 6 cross-toolchain fails:
The C++ library in GCC 6 now provides its own
<stdlib.h>header thatwraps the C library header of the same name, so in
<cstdlib>theheader include
has become
#include_nextis sensitive to the order of directories in thepreprocessor's search path, so if that order is changed with
-isystemthen the compiler can't find the right header:
<cstdlib>is located in [2] whereas<stdlib.h>(C library header) isin [1]. In this case, the
#include_next <stdlib.h>statement in<cstdlib>, located in [2], is evaluated after the search path [1],so the compiler does not find the right system header.
The problem is that the OLA build system replaces the
-Iin the CFLAGSfrom libprotobuf with
-isystemto fix some warnings treated as errorsin the libprotobuf header files.
-isystemshould be used to suppress warnings in system headers onlyand the libprotobuf header files are not system files.
The correct fix is to compile with less restrictions and remove
-Werrorfor the build.As using
-isystemis reordering GCCs search path and using-isystemis really not necessary, remove the faulty replacement of
-I.Closes: #1125