Flutter's Android tools ignore NDK symlinks and copy files instead, leading to huge disk usage

While investigating disk space shortages, I discovered that Flutter’s Android tools package includes a large NDK copy where all symlinks have been resolved into actual files.

Normal NDK from the official Android site:

[/path/to/ndk/28.2.13676358/toolchains/llvm/prebuilt/linux-x86_64/bin]$ ls -al | grep ^l
lrwxrwxrwx.  1 user user         8 Jul 27 07:59 clang -> clang-19
lrwxrwxrwx.  1 user user         5 Jul 27 07:59 clang++ -> clang
lrwxrwxrwx.  1 user user         6 Jul 27 07:59 ld -> ld.lld
lrwxrwxrwx.  1 user user         3 Jul 27 07:59 ld64.lld -> lld
lrwxrwxrwx.  1 user user         3 Jul 27 07:59 ld.lld -> lld
lrwxrwxrwx.  1 user user         3 Jul 27 07:59 lld-link -> lld
lrwxrwxrwx.  1 user user        15 Jul 27 07:59 llvm-addr2line -> llvm-symbolizer
lrwxrwxrwx.  1 user user         7 Jul 27 07:59 llvm-dlltool -> llvm-ar
lrwxrwxrwx.  1 user user         7 Jul 27 07:59 llvm-lib -> llvm-ar
lrwxrwxrwx.  1 user user         7 Jul 27 07:59 llvm-ranlib -> llvm-ar
lrwxrwxrwx.  1 user user        12 Jul 27 07:59 llvm-readelf -> llvm-readobj
lrwxrwxrwx.  1 user user        12 Jul 27 07:59 llvm-strip -> llvm-objcopy
lrwxrwxrwx.  1 user user         7 Jul 27 07:59 llvm-windres -> llvm-rc
lrwxrwxrwx.  1 user user         3 Jul 27 07:59 wasm-ld -> lld

NDK bundled with Flutter’s Android tools:

[/path/to/flutter/engine/src/flutter/third_party/android_tools/ndk/toolchains/llvm/prebuilt/linux-x86_64/bin]$ ls -al | grep ^l
[/path/to/flutter/engine/src/flutter/third_party/android_tools/ndk/toolchains/llvm/prebuilt/linux-x86_64/bin]$ ls -al clang*
-r-xr-xr-x. 1 user user 135276024 Oct  2 04:29 clang
-r-xr-xr-x. 1 user user 135276024 Oct  2 04:29 clang++
-r-xr-xr-x. 1 user user 135276024 Oct  2 04:29 clang-19
-r-xr-xr-x. 1 user user  75759408 Oct  2 04:29 clang-check
-r-xr-xr-x. 1 user user  44910272 Oct  2 04:29 clangd
-r-xr-xr-x. 1 user user   3817168 Oct  2 04:29 clang-format
-r-xr-xr-x. 1 user user  75664920 Oct  2 04:29 clang-scan-deps
-r-xr-xr-x. 1 user user  53089504 Oct  2 04:29 clang-tidy

As shown above, clang, clang++, and clang-19 are all separate files of ~135 MB each.
In the official NDK, they are symlinks to the same file.

This means Flutter’s Android tools are effectively duplicating large binaries, inflating the NDK’s size by hundreds (if not thousands) of megabytes.

Expected behavior

NDK binaries in Flutter’s Android tools should preserve symlinks instead of copying file contents.
This would significantly reduce disk usage and improve developer experience.

Environment

Flutter version: 9dff19e

@bc-lee

Hi @bc-lee
To be clear, does this issue only happen when compiling engine for Android?

I think this happens even when I don’t compile for Android.
For reference, the .gclient file of my machine is the unmodified one.

$ cat .gclient
# Copy this file to the root of your Flutter checkout to bootstrap gclient
# or just run "gclient sync" in an empty directory with this file.
solutions = [
  {
    "custom_deps": {},
    "deps_file": "DEPS",
    "managed": False,
    "name": ".",
    "safesync_url": "",

    # If you are using SSH to connect to GitHub, change the URL to:
    # [email protected]:flutter/flutter.git
    "url": "https://github.com/flutter/flutter.git",

    # Uncomment the custom_vars section below if you plan to build the web engine.
    # "custom_vars": {
    #   "download_emsdk": True,
    # },
  },
]

Thanks for confirming it. Labeling this for further insights.

@gaaclarke

@gaaclarke or @chinmaygarde is this something the engine team can take a look at? It feels like a gclient configuration thing not a android tooling thing. My guess is that any symlink would copy.

Confirmed that the symlinks are preserved with the above change, will request CIPD access and update the bundle

Confirmed that the symlinks are preserved with the above change, will request CIPD access and update the bundle

Having some mechanical trouble getting CIPD access, will upload the bundle when that gets sorted out

Copy symlinks when creating android cipd package, and update to packa…

This thread has been automatically locked since there has not been any recent activity after it was closed. If you are still experiencing a similar issue, please open a new bug, including the output of flutter doctor -v and a minimal reproduction of the issue.

Copy symlinks when creating android cipd package, and update to packa…

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Flutter's Android tools ignore NDK symlinks and copy files instead, leading to huge disk usage #177286

Normal NDK from the official Android site:

NDK bundled with Flutter’s Android tools:

Expected behavior

Environment

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Flutter's Android tools ignore NDK symlinks and copy files instead, leading to huge disk usage #177286

Description

Normal NDK from the official Android site:

NDK bundled with Flutter’s Android tools:

Expected behavior

Environment

Activity

huycozy commented on Oct 21, 2025

bc-lee commented on Oct 21, 2025

huycozy commented on Oct 22, 2025

reidbaker commented on Oct 22, 2025

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gmackall commented on Oct 28, 2025

gmackall commented on Oct 29, 2025

github-actions commented on Nov 13, 2025

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