Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Include zconf.h in example binary in order to fix CMake's add_subdirectory() #132

Open
wants to merge 1 commit into
base: master
Choose a base branch
from
Open

Include zconf.h in example binary in order to fix CMake's add_subdirectory() #132

wants to merge 1 commit into from

Conversation

Qix-
Copy link

@Qix- Qix- commented Feb 8, 2016

Alright so this probably isn't the best way to fix this.

When including zlib from a parent project using CMake's add_subdirectory() function, the build fails - but only in test/example.c.

It whines about z_const and not being able to find it. Turns out, for some reason, zconf.h isn't being included. This PR fixes that.

The other option is to have someone more familiar with the library figure out why this is happening in the first place. If I'm understanding the header hierarchy correctly, zconf.h should be included with zlib.h - but that doesn't seem to be the case with test/example.c.

Alternatively, we could also add an option to disable building the examples.

I'm at least submitting the PR so if someone else runs across the issue prior to it being fixed they'll know what to do.

@madler
Copy link
Owner

madler commented Feb 8, 2016

Yes, you are correct, this is definitely not the fix. I don't see how zconf.h would not be included without some sort of error at the include statement.

@Qix-
Copy link
Author

Qix- commented Feb 8, 2016

That's what I was wondering. As well, including zlib.h by itself in my consuming project was giving me the same errors. Didn't seem like it had anything to do with the test/example.c file being the problem.

The weird thing, indeed, is that it's including something from somewhere and not erroring out at build time regarding the include.

You can test this yourself by cloning zlib into a directory somewhere, and in a different directory creating a CMakeLists.txt file with the following line:

add_subdirectory("/path/to/zlib")

and then building it.

For instance, here's the output using Makefiles:

Scanning dependencies of target zlib
[  2%] Building C object zlib/CMakeFiles/zlib.dir/adler32.o
[  5%] Building C object zlib/CMakeFiles/zlib.dir/compress.o
[  8%] Building C object zlib/CMakeFiles/zlib.dir/crc32.o
[ 11%] Building C object zlib/CMakeFiles/zlib.dir/deflate.o
[ 13%] Building C object zlib/CMakeFiles/zlib.dir/gzclose.o
[ 16%] Building C object zlib/CMakeFiles/zlib.dir/gzlib.o
[ 19%] Building C object zlib/CMakeFiles/zlib.dir/gzread.o
[ 22%] Building C object zlib/CMakeFiles/zlib.dir/gzwrite.o
[ 25%] Building C object zlib/CMakeFiles/zlib.dir/inflate.o
[ 27%] Building C object zlib/CMakeFiles/zlib.dir/infback.o
[ 30%] Building C object zlib/CMakeFiles/zlib.dir/inftrees.o
[ 33%] Building C object zlib/CMakeFiles/zlib.dir/inffast.o
[ 36%] Building C object zlib/CMakeFiles/zlib.dir/trees.o
[ 38%] Building C object zlib/CMakeFiles/zlib.dir/uncompr.o
[ 41%] Building C object zlib/CMakeFiles/zlib.dir/zutil.o
[ 44%] Linking C shared library libz.dylib
[ 44%] Built target zlib
Scanning dependencies of target example
[ 47%] Building C object zlib/CMakeFiles/example.dir/test/example.o
/tmp/zlib/test/example.c:29:1: error: unknown type name 'z_const'; did you mean 'const'?
z_const char hello[] = "hello, hello!";
^~~~~~~
const
/tmp/zlib/test/example.c:215:26: error: use of undeclared identifier 'z_const'; did you mean 'const'?
    c_stream.next_in  = (z_const unsigned char *)hello;
                         ^~~~~~~
                         const
/tmp/zlib/test/example.c:215:26: error: expected expression
/tmp/zlib/test/example.c:390:26: error: use of undeclared identifier 'z_const'; did you mean 'const'?
    c_stream.next_in  = (z_const unsigned char *)hello;
                         ^~~~~~~
                         const
/tmp/zlib/test/example.c:390:26: error: expected expression
/tmp/zlib/test/example.c:479:25: error: use of undeclared identifier 'z_const'; did you mean 'const'?
    c_stream.next_in = (z_const unsigned char *)hello;
                        ^~~~~~~
                        const
/tmp/zlib/test/example.c:479:25: error: expected expression
7 errors generated.
make[2]: *** [zlib/CMakeFiles/example.dir/test/example.o] Error 1
make[1]: *** [zlib/CMakeFiles/example.dir/all] Error 2
make: *** [all] Error 2

@mtl1979
Copy link

mtl1979 commented Apr 21, 2016

add_subdirectory() should have two parameters... second parameter specifies directory where sub-cmake creates all output files, including zconf.h, it is also used to construct include path when compiling.

I tested with simple CMakeLists.txt:

cmake_minimum_required(VERSION 3.4)
project(TEST)

add_subdirectory("../zlib" "bin")

@jorgehatccrma
Copy link

My two cents: I also tried zlib from a parent project using add_subdirectory directive and came across the same error for example.c.

The quick way to solve it was to change #include "zlib.h" to #include "../zlib.h" in example.c. That gave me the clue of the error.

I think the proper solution is to add the following line to zlib's CMakeLists.txt, keeping example.c as it was originally (#include "zlib.h"):

target_include_directories(${PROJECT_NAME} PUBLIC ${PROJECT_BINARY_DIR})

At least that fixed it for me.

@LebedevRI LebedevRI mentioned this pull request Feb 7, 2017
Open
@LebedevRI
Copy link

@Qix-
I have also just tried using zlib via ExternalProject_Add() + add_subdirectory().
The problem is, it included zconf.h from system, not from subdirectory.

So basically, you need to do:

include_directories(BEFORE ${CMAKE_BINARY_DIR}/zlib/zlib-build)

I also do

include_directories(BEFORE ${CMAKE_BINARY_DIR}/zlib/zlib-src)`

for obivious reasons, e.g. #218

before doing add_subdirectory(${CMAKE_BINARY_DIR}/zlib/zlib-src ${CMAKE_BINARY_DIR}/zlib/zlib-build)

@lalo lalo mentioned this pull request May 31, 2017
Closed
@ptc-tgamper ptc-tgamper mentioned this pull request Dec 3, 2020
Merged
@Vollstrecker Vollstrecker mentioned this pull request Dec 11, 2024
Open
@Neustradamus Neustradamus mentioned this pull request Jan 1, 2025
Open
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Reviewers
No reviews
Assignees
No one assigned
Labels
None yet
Projects
None yet
Milestone
No milestone
Development

Successfully merging this pull request may close these issues.
5 participants
@Qix- @madler @mtl1979 @jorgehatccrma @LebedevRI