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D64579.diff
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Mon, Dec 9, 5:26 AM

D64579.diff

Index: cfe/trunk/tools/clang-shlib/CMakeLists.txt
===================================================================
--- cfe/trunk/tools/clang-shlib/CMakeLists.txt
+++ cfe/trunk/tools/clang-shlib/CMakeLists.txt
@@ -7,8 +7,35 @@
foreach (lib ${clang_libs})
list(APPEND _OBJECTS $<TARGET_OBJECTS:obj.${lib}>)
- list(APPEND _DEPS $<TARGET_PROPERTY:${lib},INTERFACE_LINK_LIBRARIES>)
- list(APPEND _DEPS $<TARGET_PROPERTY:${lib},LINK_LIBRARIES>)
+ # Use the static library for its dependencies. The objects that constitute the
+ # static library will appear on the link line before the library, so it'll
+ # just be ignored, but the dependencies of the library will still be linked
+ # correctly.
+ #
+ # We could propagate the dependencies manually using the library's
+ # INTERFACE_LINK_LIBRARIES property, but that will contain $<LINK_ONLY:...>
+ # generator expressions if a static library has a private dependency, so we
+ # can't use a $<TARGET_PROPERTY:...> generator expression to get the property
+ # (since it wouldn't evaluate any generator expressions inside the property).
+ # We could use get_property and do string manipulation to manually evaluate
+ # the $<LINK_ONLY:...>, but that would miss any dependencies added after we
+ # evaluate the get_property. We could also use the LINK_LIBRARIES property
+ # instead, which should be free of any generator expressions, but that's
+ # technically incorrect (it'd most likely work fine in practice, but still).
+ #
+ # Another alternative would be to use --whole-archive or equivalent instead of
+ # using the object library at all. However, CMake reorders static libraries on
+ # the link line so that a library appears after all its dependents, which can
+ # reorder static libraries out of their --whole-archive --no-whole-archive
+ # sandwich. It's really hard to avoid that reordering while still propagating
+ # dependencies, which defeats the whole point.
+ #
+ # The ideal solution here is to bump our minimum CMake requirement to 3.12,
+ # which adds support for dependencies on object libraries. Until then, linking
+ # both the object and the static libraries seems like the least bad solution.
+ #
+ # TODO: Rework this when we bump our minimum CMake version to 3.12 or newer.
+ list(APPEND _DEPS ${lib})
endforeach ()
add_clang_library(clang_shared

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