CMake build fails if samples enabled but webready disabled, due to conntest sample dependency

[ferdnyc]

Describe the bug

At least in the CMake build, samples/CMakeLists.txt configures building of the conntest application unconditionally when the EXIV2_BUILD_SAMPLES option is enabled. But if EXIV2_ENABLE_WEBREADY is OFF, there will be no Exiv2::http class in the library (heck, exiv2.hpp won't even include exiv2/http.hpp), and the conntest code requires Exiv2::http.

To Reproduce

Steps to reproduce the behavior:

git clone https://github.com/Exiv2/exiv2
cd exiv2
cmake -B _build -S . -DEXIV2_BUILD_SAMPLES=1 \
    -DEXIV2_ENABLE_WEBREADY=0
cmake --build _build -j6

Full compile output

[  1%] Building CXX object xmpsdk/CMakeFiles/exiv2-xmp.dir/src/ExpatAdapter.cpp.o
[  1%] Building CXX object xmpsdk/CMakeFiles/exiv2-xmp.dir/src/MD5.cpp.o
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[  2%] Building CXX object src/CMakeFiles/exiv2lib_int.dir/canonmn_int.cpp.o
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[  5%] Building CXX object xmpsdk/CMakeFiles/exiv2-xmp.dir/src/ParseRDF.cpp.o
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[  6%] Building CXX object xmpsdk/CMakeFiles/exiv2-xmp.dir/src/UnicodeConversions.cpp.o
[  7%] Building CXX object xmpsdk/CMakeFiles/exiv2-xmp.dir/src/WXMPIterator.cpp.o
[  7%] Building CXX object src/CMakeFiles/exiv2lib_int.dir/image_int.cpp.o
[  8%] Building CXX object src/CMakeFiles/exiv2lib_int.dir/jp2image_int.cpp.o
[  8%] Building CXX object src/CMakeFiles/exiv2lib_int.dir/makernote_int.cpp.o
[  9%] Building CXX object xmpsdk/CMakeFiles/exiv2-xmp.dir/src/WXMPMeta.cpp.o
[ 10%] Building CXX object src/CMakeFiles/exiv2lib_int.dir/minoltamn_int.cpp.o
[ 10%] Building CXX object xmpsdk/CMakeFiles/exiv2-xmp.dir/src/WXMPUtils.cpp.o
[ 11%] Building CXX object src/CMakeFiles/exiv2lib_int.dir/nikonmn_int.cpp.o
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[ 12%] Building CXX object xmpsdk/CMakeFiles/exiv2-xmp.dir/src/XML_Node.cpp.o
[ 13%] Building CXX object src/CMakeFiles/exiv2lib_int.dir/orfimage_int.cpp.o
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[ 15%] Building CXX object xmpsdk/CMakeFiles/exiv2-xmp.dir/src/XMPIterator.cpp.o
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[ 17%] Building CXX object xmpsdk/CMakeFiles/exiv2-xmp.dir/src/XMPMeta-GetSet.cpp.o
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[ 21%] Building CXX object xmpsdk/CMakeFiles/exiv2-xmp.dir/src/XMPMeta-Serialize.cpp.o
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[ 23%] Building CXX object src/CMakeFiles/exiv2lib_int.dir/utils.cpp.o
[ 23%] Building CXX object xmpsdk/CMakeFiles/exiv2-xmp.dir/src/XMPMeta.cpp.o
[ 24%] Building CXX object xmpsdk/CMakeFiles/exiv2-xmp.dir/src/XMPUtils-FileInfo.cpp.o
[ 25%] Building CXX object xmpsdk/CMakeFiles/exiv2-xmp.dir/src/XMPUtils.cpp.o
[ 25%] Building CXX object src/CMakeFiles/exiv2lib_int.dir/pngchunk_int.cpp.o
.../exiv2/xmpsdk/src/XMPUtils.cpp: In static member function ‘static XMP_Int64 XMPUtils::ConvertToInt64(XMP_StringPtr)’:
.../exiv2/xmpsdk/src/XMPUtils.cpp:1221:48: warning: format ‘%lld’ expects argument of type ‘long long int*’, but argument 3 has type ‘XMP_Int64*’ {aka ‘long int*’} [-Wformat=]
 1221 |                 count = sscanf ( strValue, "%lld%c", &result, &nextCh );
      |                                             ~~~^     ~~~~~~~
      |                                                |     |
      |                                                |     XMP_Int64* {aka long int*}
      |                                                long long int*
      |                                             %ld
.../exiv2/xmpsdk/src/XMPUtils.cpp:1223:48: warning: format ‘%llx’ expects argument of type ‘long long unsigned int*’, but argument 3 has type ‘XMP_Int64*’ {aka ‘long int*’} [-Wformat=]
 1223 |                 count = sscanf ( strValue, "%llx%c", &result, &nextCh );
      |                                             ~~~^     ~~~~~~~
      |                                                |     |
      |                                                |     XMP_Int64* {aka long int*}
      |                                                long long unsigned int*
      |                                             %lx
.../exiv2/xmpsdk/src/XMPMeta.cpp: In function ‘XMP_Status DumpNodeOptions(XMP_OptionBits, XMP_TextOutputProc, void*)’:
.../exiv2/xmpsdk/src/XMPMeta.cpp:90:70: warning: format ‘%lX’ expects argument of type ‘long unsigned int’, but argument 4 has type ‘XMP_OptionBits’ {aka ‘unsigned int’} [-Wformat=]
   90 | #define OutProcHexInt(num)      { snprintf ( buffer, sizeof(buffer), "%lX", (num) ); /* AUDIT: Using sizeof for snprintf length is safe */      \
      |                                                                      ^~~~~  ~~~~~
.../exiv2/xmpsdk/src/XMPMeta.cpp:241:17: note: in expansion of macro ‘OutProcHexInt’
  241 |                 OutProcHexInt ( options );
      |                 ^~~~~~~~~~~~~
.../exiv2/xmpsdk/src/XMPMeta.cpp:90:73: note: format string is defined here
   90 | #define OutProcHexInt(num)      { snprintf ( buffer, sizeof(buffer), "%lX", (num) ); /* AUDIT: Using sizeof for snprintf length is safe */      \
      |                                                                       ~~^
      |                                                                         |
      |                                                                         long unsigned int
      |                                                                       %X
[ 25%] Built target exiv2-xmp
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[ 30%] Building CXX object src/CMakeFiles/exiv2lib.dir/datasets.cpp.o
[ 30%] Building CXX object src/CMakeFiles/exiv2lib.dir/easyaccess.cpp.o
[ 31%] Building CXX object src/CMakeFiles/exiv2lib.dir/epsimage.cpp.o
[ 32%] Building CXX object src/CMakeFiles/exiv2lib.dir/error.cpp.o
[ 32%] Building CXX object src/CMakeFiles/exiv2lib.dir/exif.cpp.o
[ 33%] Building CXX object src/CMakeFiles/exiv2lib.dir/futils.cpp.o
[ 33%] Building CXX object src/CMakeFiles/exiv2lib.dir/gifimage.cpp.o
[ 34%] Building CXX object src/CMakeFiles/exiv2lib.dir/image.cpp.o
[ 35%] Building CXX object src/CMakeFiles/exiv2lib.dir/iptc.cpp.o
[ 35%] Building CXX object src/CMakeFiles/exiv2lib.dir/jp2image.cpp.o
[ 36%] Building CXX object src/CMakeFiles/exiv2lib.dir/jpgimage.cpp.o
[ 37%] Building CXX object src/CMakeFiles/exiv2lib.dir/metadatum.cpp.o
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[ 38%] Building CXX object src/CMakeFiles/exiv2lib.dir/orfimage.cpp.o
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[ 46%] Building CXX object src/CMakeFiles/exiv2lib.dir/version.cpp.o
[ 46%] Building CXX object src/CMakeFiles/exiv2lib.dir/webpimage.cpp.o
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[ 50%] Building CXX object src/CMakeFiles/exiv2lib.dir/quicktimevideo.cpp.o
[ 50%] Building CXX object src/CMakeFiles/exiv2lib.dir/riffvideo.cpp.o
[ 51%] Linking CXX shared library ../lib/libexiv2.so
[ 51%] Built target exiv2lib
[ 52%] Building CXX object samples/CMakeFiles/convert-test.dir/convert-test.cpp.o
[ 52%] Building CXX object app/CMakeFiles/exiv2.dir/exiv2.cpp.o
[ 53%] Building CXX object samples/CMakeFiles/exifdata-test.dir/exifdata-test.cpp.o
[ 54%] Building CXX object samples/CMakeFiles/exifcomment.dir/exifcomment.cpp.o
[ 55%] Building CXX object samples/CMakeFiles/addmoddel.dir/addmoddel.cpp.o
[ 55%] Building CXX object samples/CMakeFiles/easyaccess-test.dir/easyaccess-test.cpp.o
[ 56%] Linking CXX executable ../bin/exifcomment
[ 56%] Built target exifcomment
[ 57%] Building CXX object app/CMakeFiles/exiv2.dir/actions.cpp.o
[ 57%] Linking CXX executable ../bin/convert-test
[ 57%] Built target convert-test
[ 57%] Building CXX object samples/CMakeFiles/exifdata.dir/exifdata.cpp.o
[ 57%] Linking CXX executable ../bin/easyaccess-test
[ 57%] Built target easyaccess-test
[ 58%] Building CXX object app/CMakeFiles/exiv2.dir/getopt.cpp.o
[ 59%] Linking CXX executable ../bin/addmoddel
[ 59%] Linking CXX executable ../bin/exifdata-test
[ 59%] Built target addmoddel
[ 60%] Building CXX object samples/CMakeFiles/exifprint.dir/exifprint.cpp.o
[ 60%] Built target exifdata-test
[ 60%] Building CXX object app/CMakeFiles/exiv2.dir/app_utils.cpp.o
[ 61%] Building CXX object samples/CMakeFiles/exifvalue.dir/exifvalue.cpp.o
[ 62%] Building CXX object samples/CMakeFiles/ini-test.dir/ini-test.cpp.o
[ 63%] Linking CXX executable ../bin/exifdata
[ 63%] Built target exifdata
[ 63%] Building CXX object samples/CMakeFiles/iotest.dir/iotest.cpp.o
[ 64%] Linking CXX executable ../bin/exifvalue
[ 64%] Linking CXX executable ../bin/exifprint
[ 64%] Built target exifvalue
[ 65%] Linking CXX executable ../bin/ini-test
[ 66%] Building CXX object samples/CMakeFiles/iptceasy.dir/iptceasy.cpp.o
[ 66%] Built target exifprint
[ 66%] Built target ini-test
[ 67%] Building CXX object samples/CMakeFiles/iptcprint.dir/iptcprint.cpp.o
[ 68%] Building CXX object samples/CMakeFiles/iptctest.dir/iptctest.cpp.o
[ 69%] Linking CXX executable ../bin/iotest
[ 69%] Linking CXX executable ../bin/iptcprint
[ 69%] Linking CXX executable ../bin/iptceasy
[ 69%] Built target iotest
[ 69%] Building CXX object samples/CMakeFiles/jpegparsetest.dir/jpegparsetest.cpp.o
[ 69%] Built target iptceasy
[ 69%] Built target iptcprint
[ 70%] Building CXX object samples/CMakeFiles/key-test.dir/key-test.cpp.o
[ 71%] Building CXX object samples/CMakeFiles/largeiptc-test.dir/largeiptc-test.cpp.o
[ 72%] Linking CXX executable ../bin/iptctest
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[ 73%] Building CXX object samples/CMakeFiles/mmap-test.dir/mmap-test.cpp.o
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[ 75%] Linking CXX executable ../bin/jpegparsetest
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[ 75%] Building CXX object samples/CMakeFiles/prevtest.dir/prevtest.cpp.o
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[ 76%] Linking CXX executable ../bin/exiv2
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[ 77%] Built target exiv2
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[ 78%] Linking CXX executable ../bin/mmap-test
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[ 80%] Linking CXX executable ../bin/stringto-test
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[ 81%] Linking CXX executable ../bin/taglist
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[ 81%] Built target taglist
[ 81%] Building CXX object samples/CMakeFiles/xmpparser-test.dir/xmpparser-test.cpp.o
[ 82%] Linking CXX executable ../bin/prevtest
[ 82%] Built target prevtest
[ 83%] Building CXX object samples/CMakeFiles/xmpprint.dir/xmpprint.cpp.o
[ 84%] Linking CXX executable ../bin/tiff-test
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[ 85%] Linking CXX executable ../bin/write2-test
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[ 92%] Linking CXX executable ../bin/xmpparser-test
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[ 93%] Building CXX object samples/CMakeFiles/geotag.dir/geotag.cpp.o
[ 94%] Linking CXX executable ../bin/xmpsample
[ 94%] Linking CXX executable ../bin/getopt-test
[ 95%] Linking CXX executable ../bin/xmpdump
[ 95%] Built target xmpsample
[ 96%] Building CXX object samples/CMakeFiles/path-test.dir/__/app/getopt.cpp.o
[ 96%] Building CXX object samples/CMakeFiles/conntest.dir/conntest.cpp.o
[ 96%] Built target xmpdump
[ 96%] Built target getopt-test
[ 96%] Building CXX object samples/CMakeFiles/remotetest.dir/remotetest.cpp.o
[ 96%] Linking CXX executable ../bin/metacopy
[ 96%] Built target metacopy
[ 97%] Linking CXX executable ../bin/path-test
[ 97%] Built target path-test
.../exiv2/samples/conntest.cpp: In function ‘void httpcon(const std::string&, bool)’:
.../exiv2/samples/conntest.cpp:25:27: error: ‘http’ is not a member of ‘Exiv2’
   25 |   int serverCode = Exiv2::http(request, response, errors);
      |                           ^~~~
gmake[2]: *** [samples/CMakeFiles/conntest.dir/build.make:76: samples/CMakeFiles/conntest.dir/conntest.cpp.o] Error 1
gmake[1]: *** [CMakeFiles/Makefile2:1996: samples/CMakeFiles/conntest.dir/all] Error 2
gmake[1]: *** Waiting for unfinished jobs....

Relevant compile error:

[ 96%] Building CXX object samples/CMakeFiles/conntest.dir/conntest.cpp.o
.../exiv2/samples/conntest.cpp: In function ‘void httpcon(const std::string&, bool)’:
.../exiv2/samples/conntest.cpp:25:27: error: ‘http’ is not a member of ‘Exiv2’
   25 |   int serverCode = Exiv2::http(request, response, errors);
      |                           ^~~~
gmake[2]: *** [samples/CMakeFiles/conntest.dir/build.make:76: samples/CMakeFiles/conntest.dir/conntest.cpp.o] Error 1
gmake[1]: *** [CMakeFiles/Makefile2:1996: samples/CMakeFiles/conntest.dir/all] Error 2
gmake[1]: *** Waiting for unfinished jobs....

Expected behavior

The conntest sample isn't built, because the library lacks HTTP support.

Desktop (please complete the following information):

• OS and version: Fedora Linux 39
• Exiv2 version and source: repo main branch
• Compiler and version: gcc (GCC) 13.2.1 20240316 (Red Hat 13.2.1-7)
• Compilation mode and/or compiler flags: CMake-config defaults

Additional context

This change to samples/CMakeLists.txt enabled the build to complete:

diff --git a/samples/CMakeLists.txt b/samples/CMakeLists.txt
index 3e990fbdd..bc948a1ad 100644
--- a/samples/CMakeLists.txt
+++ b/samples/CMakeLists.txt
@@ -92,10 +92,9 @@ endif()
 
 # ******************************************************************************
 # connection test application
-add_executable(conntest conntest.cpp)
-list(APPEND APPLICATIONS conntest)
-
 if(EXIV2_ENABLE_WEBREADY)
+  add_executable(conntest conntest.cpp)
+  list(APPEND APPLICATIONS conntest)
   if(EXIV2_ENABLE_CURL)
     target_include_directories(conntest SYSTEM PRIVATE ${CURL_INCLUDE_DIR})
     target_link_libraries(conntest PRIVATE ${CURL_LIBRARIES})

[ferdnyc]

Meson doesn't have the same issue, because the fake curl_dep is configured as a disabler when get_option('webready') is false. So, setting it as a dependency of conntest automatically removes it from the list of executables to be compiled.

exiv2/meson.build

Lines 70 to 74 in 41959b4

	if get_option('webready')
	curl_dep = dependency('libcurl', disabler: true, required: get_option('curl'))
	else
	curl_dep = dependency('', disabler: true, required: false)
	endif

exiv2/meson.build

Lines 158 to 165 in 41959b4

	samples = {
	'addmoddel': [],
	'conntest': curl_dep,
	'convert-test': [],
	'easyaccess-test': [],
	'exifcomment': [],
	'exifdata-test': [],
	'exifdata': [],

exiv2/meson.build

Lines 192 to 194 in 41959b4

	foreach s, d : samples
	executable(s, 'samples/@0@.cpp'.format(s), dependencies: [exiv2_dep, d], include_directories: exiv2inc)
	endforeach

[kmilos]

Thank you for the report and the suggested fix. Are you able to submit a PR directly perhaps?

[ferdnyc]

...Actually, that Meson code seems strange to me — curl_dep is also set as a disabler when get_option('webready') is true, but it's also set required. (The first branch of the conditional is a bit odd there, as we already know get_option('webready') is true if we're on that branch.)

But dependency(..., disabler: true, required: true) seems like a nonsensical combination of options. In fact I'll be a bit surprised if Meson doesn't grumble about it, if the build is configured that way.

The net effect of all that is that curl is required when building a webready exiv2, which isn't the case in the CMake configuration. There, it's permissible to build with -DEXIV2_ENABLE_WEBREADY=1 -DEXIV2_ENABLE_CURL=0, and conntest does build and work (supporting http:// URLs only) even without curl.

[ferdnyc]

Thank you for the report and the suggested fix. Are you able to submit a PR directly perhaps?

Sure, will do.

[kmilos]

Actually, that Meson code seems strange to me

@neheb can best comment on Meson...

[ferdnyc]

(The first branch of the conditional is a bit odd there, as we already know get_option('webready') is true if we're on that branch.)

But dependency(..., disabler: true, required: true) seems like a nonsensical combination of options. In fact I'll be a bit surprised if Meson doesn't grumble about it, if the build is configured that way.

Nope, I read that wrong. I had it in my head that the code was,

if get_option('webready')
  curl_dep = dependency(
    'libcurl', disabler: true, required: get_option('webready'))

But it's not, it's

  curl_dep = dependency(
    'libcurl', disabler: true, required: get_option('curl'))

My mistake, sorry.

But the curl-is-effectively-required thing is still somewhat the case. (It will only affect conntest, though, since curl_dep isn't set as a library dependency unless curl_dep.found() is true. That way it will never disable the library build.)

But a disabler curl_dep will prevent the build of conntest when libcurl isn't available. In CMake, conntest — like libexiv2 itself — can be built "webready" with limited, HTTP-only support, even if it's not linked to curl.