Add soname to libShowMySky

[mattiaverga]

To meet criteria for packaging CalcMySky into Fedora, I'd like to propose to add soname to libShowMySky.
Ref: https://bugzilla.redhat.com/show_bug.cgi?id=2131842

[DarthGandalf]

Reading the bug linked, I don't think soname by itself will help. You'll also need to patch Stellarium to open libShowMySky.so.0 in runtime instead of libShowMySky.so

[10110111]

Reading the bug linked, I don't think soname by itself will help.

Why? The bug talks about policy (comment 3) and package splitting (comment 6), not solving technical problems, and in this case adding soname seems to be sufficient.

[DarthGandalf]

The libShowMySky.so would be in -devel package, and libShowMySky.so.0 would be in the main package. So if stellarium tries to open libShowMySky.so, it still needs to depend on the devel package.

Libraries which link during build time, don't have this problem because the executable remembers that it needs to load .so.0. That's why .so is only useful during build time to resolve -lShowMySky-like flag to ld

[10110111]

Hmm, you're right. Just checked, indeed it doesn't load if I remove libShowMySky.so.

[DarthGandalf]

/usr/bin/showmysky itself also opens it like that, so would also need to be moved to the devel package, or patched

[10110111]

I think I'll add a version argument to the QLibrary constructor. This way it should work in the same manner as direct linking does. A quick check shows that it works.

[10110111]

Pushed 8e535d2.

[mattiaverga]

Sorry, I admit I know nearly nothing of programming and I did a shot in the dark here.

So, I assume that also stellarium needs a way to read the value of ShowMySky_ABI_version during build time and add it to the QLibrary constructor?

[10110111]

With current master of CalcMySky the patch for vanilla Stellarium v1.0 should look something like this:

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 902239662d..ef21a6b872 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -685,10 +685,10 @@ SET(CMAKE_AUTOUIC ON) # ?
 SET(CMAKE_INCLUDE_CURRENT_DIR ON)
 
 IF(ENABLE_SHOWMYSKY)
-    FIND_PACKAGE(ShowMySky REQUIRED)
+    FIND_PACKAGE(ShowMySky-Qt${QT_VERSION_MAJOR} REQUIRED)
     ADD_DEFINITIONS(-DENABLE_SHOWMYSKY)
-    GET_TARGET_PROPERTY(ShowMySky_INCLUDE_DIRECTORIES ShowMySky::ShowMySky INTERFACE_INCLUDE_DIRECTORIES)
-    GET_TARGET_PROPERTY(ShowMySky_LIBRARY ShowMySky::ShowMySky LOCATION)
+    GET_TARGET_PROPERTY(ShowMySky-Qt${QT_VERSION_MAJOR}_INCLUDE_DIRECTORIES ShowMySky::ShowMySky INTERFACE_INCLUDE_DIRECTORIES)
+    GET_TARGET_PROPERTY(ShowMySky-Qt${QT_VERSION_MAJOR}_LIBRARY ShowMySky::ShowMySky LOCATION)
     IF(EXISTS ${ShowMySky_LIBRARY})
     MESSAGE(STATUS "Found ShowMySky library: ${ShowMySky_LIBRARY}")
     ELSE()
diff --git a/src/core/modules/AtmosphereShowMySky.cpp b/src/core/modules/AtmosphereShowMySky.cpp
index 41b3538ca3..f58406d09c 100644
--- a/src/core/modules/AtmosphereShowMySky.cpp
+++ b/src/core/modules/AtmosphereShowMySky.cpp
@@ -407,7 +407,7 @@ void AtmosphereShowMySky::resolveFunctions()
 }
 
 AtmosphereShowMySky::AtmosphereShowMySky()
-    : showMySkyLib("ShowMySky")
+    : showMySkyLib(SHOWMYSKY_LIB_NAME, ShowMySky_ABI_version)
     , viewport(0,0,0,0)
     , gridMaxY(44)
     , gridMaxX(44)