(arrow) branch main updated: GH-51343: [C++][CI][Packaging] Disable Precompile Headers on simdjson to avoid not reproducible artifacts (#51355)

[kou]

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The following commit(s) were added to refs/heads/main by this push:
     new 0bd8def07f GH-51343: [C++][CI][Packaging] Disable Precompile Headers 
on simdjson to avoid not reproducible artifacts (#51355)
0bd8def07f is described below

commit 0bd8def07f87443df4f96ade5917b268d2ff01d0
Author: Raúl Cumplido <raulcumpl...@gmail.com>
AuthorDate: Thu Sep 17 02:32:13 2026 +0200

    GH-51343: [C++][CI][Packaging] Disable Precompile Headers on simdjson to 
avoid not reproducible artifacts (#51355)
    
    ### Rationale for this change
    
    Reproducible builds are currently failing since simdjson changes were 
merged.
    
    ### What changes are included in this PR?
    
    Disable Precompiled Headers on simdjson to avoid failing reproducible 
builds.
    
    ### Are these changes tested?
    
    Yes on CI
    
    ### Are there any user-facing changes?
    
    No
    
    ### Was AI used for this PR?
    
    In accordance to the [AI generation 
guidelines](https://arrow.apache.org/docs/dev/developers/overview.html#ai-generated-code),
 please disclose below whether and how AI was used in this PR.
    
    **PR code and description written by:**
    
    - [x] Human
    - [ ] AI
    
    **Reviewed before submission by:**
    
    - [x] Human
    - [ ] AI
    - [ ] Not reviewed
    
    Note: AI was used to diagnose the reproducible build failure otuput from 
diffoscope, failure on this gist:
    https://gist.github.com/raulcd/b2961cc053ae2d3033742e790d474b5b
    * GitHub Issue: #51343
    
    Authored-by: Raúl Cumplido <raulcumpl...@gmail.com>
    Signed-off-by: Sutou Kouhei <k...@clear-code.com>
---
 cpp/cmake_modules/ThirdpartyToolchain.cmake | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/cpp/cmake_modules/ThirdpartyToolchain.cmake 
b/cpp/cmake_modules/ThirdpartyToolchain.cmake
index 56f781bb7c..4b442990aa 100644
--- a/cpp/cmake_modules/ThirdpartyToolchain.cmake
+++ b/cpp/cmake_modules/ThirdpartyToolchain.cmake
@@ -2834,6 +2834,11 @@ function(build_simdjson)
 
   prepare_fetchcontent()
 
+  # simdjson enables precompiled headers unconditionally.
+  # Recompiling simdjson.cpp against it produces differing artifacts
+  # Disable precompiled headers to avoid reproducible build failures.
+  set(CMAKE_DISABLE_PRECOMPILE_HEADERS ON)
+
   fetchcontent_makeavailable(simdjson)
 
   target_compile_definitions(simdjson PUBLIC SIMDJSON_EXCEPTIONS=0)