Disable LTO for ZLIB

[jviotti]

Signed-off-by: Juan Cruz Viotti jv@jviotti.com

[augmentcode]

🤖 Augment PR Summary

Summary: Disables LTO when building the vendored zlib target under GCC.

Motivation: Works around a GCC LTO linker plugin issue where the zlib archive may not be rescanned for transitive dependencies, leading to link failures in LTO builds.

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[augmentcode]

Review completed. 1 suggestion posted.

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[augmentcode]

If the project enables LTO globally (e.g., via INTERPROCEDURAL_OPTIMIZATION/CMAKE_INTERPROCEDURAL_OPTIMIZATION), it’s worth double-checking that adding -fno-lto here reliably overrides any injected -flto so zlib is truly built non-LTO in those configurations. Otherwise the GCC LTO plugin issue this comment mentions could still reproduce.

Severity: medium

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[cubic-dev-ai]

1 issue found across 1 file

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="cmake/FindZLIB.cmake">

<violation number="1" location="cmake/FindZLIB.cmake:70">
P2: Scope this LTO workaround to static zlib builds; as written it also disables LTO for shared builds that are not affected by the archive-rescan issue.</violation>
</file>

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[cubic-dev-ai]

P2: Scope this LTO workaround to static zlib builds; as written it also disables LTO for shared builds that are not affected by the archive-rescan issue.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At cmake/FindZLIB.cmake, line 70:

<comment>Scope this LTO workaround to static zlib builds; as written it also disables LTO for shared builds that are not affected by the archive-rescan issue.</comment>

<file context>
@@ -64,6 +64,12 @@ if(NOT ZLIB_FOUND)
+
+    # Disable LTO for zlib to work around GCC LTO linker plugin not
+    # properly rescanning this archive for transitive dependencies
+    if(HYDRA_COMPILER_GCC)
+      target_compile_options(zlib PRIVATE -fno-lto)
+    endif()
</file context>

Suggested change

	if(HYDRA_COMPILER_GCC)
	if(HYDRA_COMPILER_GCC AND NOT BUILD_SHARED_LIBS)