[Mlir-commits] [mlir] e3c0454 - [CMake] Propagate dependencies to OBJECT libraries in `add_llvm_library` (#183541)

[llvmlistbot at llvm.org]

Author: Johannes de Fine Licht
Date: 2026-02-28T02:05:38+02:00
New Revision: e3c045415ae52167e197d4a6ed4ad5a04e49423a

URL: https://github.com/llvm/llvm-project/commit/e3c045415ae52167e197d4a6ed4ad5a04e49423a
DIFF: https://github.com/llvm/llvm-project/commit/e3c045415ae52167e197d4a6ed4ad5a04e49423a.diff

LOG: [CMake] Propagate dependencies to OBJECT libraries in `add_llvm_library` (#183541)

Previously, transitively inherited calls to
`target_include_directories(foo SYSTEM ...)` were being squashed into a
flat list of includes, effectively stripping off `-isystem` and
unintentionally forwarding warnings from such dependencies.

To correctly propagate `SYSTEM` dependencies, use
`target_link_libraries` to forward the parent target's link dependencies
to the OBJECT library (similar to the `_static` flow below). Unlike a
flat `target_include_directories`, this lets CMake resolve transitive
SYSTEM include directories through the proper dependency chain.

Note that `target_link_libraries` on an OBJECT library propagates all
usage requirements, not just includes. This also brings in transitive
`INTERFACE_COMPILE_DEFINITIONS`, `INTERFACE_COMPILE_OPTIONS`, and
`INTERFACE_COMPILE_FEATURES`. This is arguably more correct, as the
OBJECT library compiles the same sources and should see the same flags.

The existing `target_include_directories` call is retained for include
directories set directly on the target (not through link dependencies).
CMake deduplicates include directories that appear through both paths.
Compile definitions and options may technically appear twice (once via
the OBJECT library, once via the consuming target), but duplicate `-D`
and flag entries should be harmless in practice.

Also fix `clang_target_link_libraries` and `mlir_target_link_libraries`
to forward the link type (PUBLIC/PRIVATE/INTERFACE) to `obj.*` targets.
Previously the type keyword was silently dropped, resulting in
plain-signature `target_link_libraries` calls. This is now required
because the new keyword-signature call in `llvm_add_library` would
otherwise conflict (CMake requires all calls on a target to use the same
signature).

Added: 
    

Modified: 
    clang/cmake/modules/AddClang.cmake
    llvm/cmake/modules/AddLLVM.cmake
    mlir/cmake/modules/AddMLIR.cmake

Removed: 
    


################################################################################
diff  --git a/clang/cmake/modules/AddClang.cmake b/clang/cmake/modules/AddClang.cmake
index c811b7f459126..e2112d7c326e2 100644
--- a/clang/cmake/modules/AddClang.cmake
+++ b/clang/cmake/modules/AddClang.cmake
@@ -217,7 +217,7 @@ endmacro()
 
 function(clang_target_link_libraries target type)
   if (TARGET obj.${target})
-    target_link_libraries(obj.${target} ${ARGN})
+    target_link_libraries(obj.${target} ${type} ${ARGN})
   endif()
 
   get_property(LLVM_DRIVER_TOOLS GLOBAL PROPERTY LLVM_DRIVER_TOOLS)

diff  --git a/llvm/cmake/modules/AddLLVM.cmake b/llvm/cmake/modules/AddLLVM.cmake
index f59002bc6c837..386ffd99c570b 100644
--- a/llvm/cmake/modules/AddLLVM.cmake
+++ b/llvm/cmake/modules/AddLLVM.cmake
@@ -636,7 +636,12 @@ function(llvm_add_library name)
     # Do add_dependencies(obj) later due to CMake issue 14747.
     list(APPEND objlibs ${obj_name})
 
-    # Bring in the target include directories from our original target.
+    # Bring in the target include directories and link info from our original
+    # target. target_link_libraries propagates transitive dependencies with
+    # proper SYSTEM include handling from IMPORTED targets.
+    # target_include_directories propagates include directories set directly on
+    # the target.
+    target_link_libraries(${obj_name} PRIVATE $<TARGET_PROPERTY:${name},LINK_LIBRARIES>)
     target_include_directories(${obj_name} PRIVATE $<TARGET_PROPERTY:${name},INCLUDE_DIRECTORIES>)
 
     set_target_properties(${obj_name} PROPERTIES FOLDER "${subproject_title}/Object Libraries")

diff  --git a/mlir/cmake/modules/AddMLIR.cmake b/mlir/cmake/modules/AddMLIR.cmake
index b240aeba23109..60b73876d53fe 100644
--- a/mlir/cmake/modules/AddMLIR.cmake
+++ b/mlir/cmake/modules/AddMLIR.cmake
@@ -769,7 +769,7 @@ endfunction(mlir_check_all_link_libraries)
 # used.
 function(mlir_target_link_libraries target type)
   if (TARGET obj.${target})
-    target_link_libraries(obj.${target} ${ARGN})
+    target_link_libraries(obj.${target} ${type} ${ARGN})
   endif()
 
   if (MLIR_LINK_MLIR_DYLIB)