[llvm][cmake] Add clang if not already present when building lldb#149055
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DavidSpickett merged 2 commits intollvm:mainfrom Jul 17, 2025
Merged
[llvm][cmake] Add clang if not already present when building lldb#149055DavidSpickett merged 2 commits intollvm:mainfrom
DavidSpickett merged 2 commits intollvm:mainfrom
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Fixes llvm#54555 We could do what flang does and enable clang automatically, but I personally prefer making the user make the choice. Also from a buld requirements perspective, flang is a bigger build than clang. So if you're already set on building flang, clang should be within your budget too. lldb is smaller than clang.
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As suggested by @labath #54555 (comment). |
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@llvm/pr-subscribers-lldb Author: David Spickett (DavidSpickett) ChangesFixes #54555 We could do what flang does and enable clang automatically, but I personally prefer making the user make the choice. Also from a buld requirements perspective, flang is a bigger build than clang. So if you're already set on building flang, clang should be within your budget too. lldb is smaller than clang. Full diff: https://github.com/llvm/llvm-project/pull/149055.diff 1 Files Affected:
diff --git a/llvm/CMakeLists.txt b/llvm/CMakeLists.txt
index 3f8201fa426fe..bf52533abe525 100644
--- a/llvm/CMakeLists.txt
+++ b/llvm/CMakeLists.txt
@@ -179,6 +179,12 @@ if ("flang" IN_LIST LLVM_ENABLE_PROJECTS)
endif ()
endif()
+if ("lldb" IN_LIST LLVM_ENABLE_PROJECTS)
+ if (NOT "clang" IN_LIST LLVM_ENABLE_PROJECTS)
+ message(FATAL_ERROR "Clang is not enabled, but is required for lldb.")
+ endif ()
+endif ()
+
if ("libc" IN_LIST LLVM_ENABLE_PROJECTS)
message(WARNING "Using LLVM_ENABLE_PROJECTS=libc is deprecated. Please use "
"-DLLVM_ENABLE_RUNTIMES=libc or see the instructions at "
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You might wonder what a standalone build does when clang isn't in the base build, I also wonder this because I have not been able to get it to build at all :) So I might do a follow up for standalone if I can work around the problems. |
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I would prefer that too, but I think there's also value in consistency. Unless you're really set on this, I think we should do what flang does. |
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I've done it the flang way. |
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User error on my part, it works fine and because it uses CMake's config mechanism to find clang it does fail in a reasonable way. |
JDevlieghere
approved these changes
Jul 16, 2025
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LGTM. IIUC this works for the standalone build because when building LLDB, we point it to llvm-project/lldb as the CMake root and don't specify LLVM_ENABLE_PROJECTS
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I think that's right. I will double check that this doesn't make the "standalone" lldb in fact build clang as well. |
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I'm okay with merging this and keeping an eye on https://ci.swift.org/view/all/job/llvm.org/view/LLDB/job/lldb-cmake-standalone/ which covers all the standalone scenarios we officially support. |
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It does not. |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/18/builds/19135 Here is the relevant piece of the build log for the reference |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/198/builds/6231 Here is the relevant piece of the build log for the reference |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/153/builds/38425 Here is the relevant piece of the build log for the reference |
This was referenced Jul 23, 2025
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Fixes #54555
This follows flang's pattern, it adds clang if you don't have it in LLVM_ENABLE_PROJECTS.