PyROOT macro compilation fails on macOS due to libffi-trampolines.dylib linking restriction

[diegobaronm]

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• Checked for duplicates

Description

When using PyROOT to compile a macro with .L macro.C+, compilation fails with the following linker error:

ld: cannot link directly with 'libffi-trampolines.dylib' because product being built is not an allowed client of it
clang++: error: linker command failed with exit code 1 (use -v to see invocation)

Standalone ROOT compiles the same macro fine (root -l .L macro.C+), so this only occurs when running ROOT inside Python.

Environment:
• ROOT version: 6.38.04 (Homebrew)
• Installation method: Homebrew (brew install root)
• Python version: 3.14.3 (Homebrew)
• macOS version: 26.3.1 (Apple Silicon)

Reproducer

Create a minimal macro test_macro.C:

#include <iostream>
void test() {
    std::cout << "hello" << std::endl;
}

in a python session:

import ROOT
ROOT.gROOT.ProcessLine(".L test_macro.C+")

ROOT version

---

| Welcome to ROOT 6.38.04 https://root.cern |
| (c) 1995-2025, The ROOT Team; conception: R. Brun, F. Rademakers |
| Built for macosxarm64 on Mar 11 2026, 21:39:24 |
| From tags/6-38-04@6-38-04 |
| With Apple clang version 17.0.0 (clang-1700.6.4.2) std201703 |
| Try '.help'/'.?', '.demo', '.license', '.credits', '.quit'/'.q' |

Installation method

Homebrew

Operating system

macOS version: 26.3.1 (Apple Silicon)

Additional context

Doing this solves the problem

export DYLD_LIBRARY_PATH=/opt/homebrew/opt/libffi/lib:$DYLD_LIBRARY_PATH

[vepadulano]

Hi @diegobaronm ,

Thanks for reaching out. I will try to reproduce this situation on one of our MacOS CI nodes. Meanwhile, I got a doubt by reading this last part of your issue

Doing this solves the problem
export DYLD_LIBRARY_PATH=/opt/homebrew/opt/libffi/lib:$DYLD_LIBRARY_PATH

That sounds like this could be an issue with how homebrew packages ROOT, do the homebrew maintainers know about this issue?

[diegobaronm]

Hi @vepadulano ,

Thanks for having a look. They do not know. Can you confirm this the place to report it?

Cheers, Diego

[vepadulano]

Hi @diegobaronm ,

Yes indeed that is the correct github issue tracker.

[diegobaronm]

Hi @vepadulano ,

Reported to the homebrew maintainers. See here.

[vepadulano]

First attempt is inconclusive. I built ROOT on one of the MacOS nodes of the CI:

$: sw_vers
ProductName:		macOS
ProductVersion:		15.7.4
BuildVersion:		24G517
$: git clone https://github.com/root-project/root
$: cmake -B build -S root
$: cmake --build build
$: PYTHONPATH=build/lib python3
Python 3.11.0 (v3.11.0:deaf509e8f, Oct 24 2022, 14:43:23) [Clang 13.0.0 (clang-1300.0.29.30)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import ROOT
>>> ROOT.gInterpreter.ProcessLine(".L test.C")
0
>>> ROOT.gInterpreter.ProcessLine("test()")
hello
0

So there seems to be something different at least between this node and the homebrew package.

[diegobaronm]

Hi @vepadulano ,

Thanks for investigating. This means that building ROOT from source is fine. But the problem I saw appears when using the homebrew formula.