Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

macOS linking -flat_namespace changes user-facing behavior #11937

Closed
Axel-Naumann opened this issue Dec 20, 2022 · 5 comments · Fixed by #12045
Closed

macOS linking -flat_namespace changes user-facing behavior #11937

Axel-Naumann opened this issue Dec 20, 2022 · 5 comments · Fixed by #12045
Assignees
@Axel-Naumann
Labels
affects:master affects:6.26 bug in:Build System priority:critical
Milestone
6.28/00

Comments

@Axel-Naumann
Copy link
Member

From @henryiii :

ROOT can't pass homebrew's audit any more because it is now injecting -flat_namespace. Flat namespaces have been deprecated since the move to Intel. I believe this was done due to -undefined dynamic_lookup producing a warning - Apple plans to add something to replace this in the future, but it's not the old -flat_namespace. See Homebrew/homebrew-core#114543 (comment)
Flat namespace makes major changes to the layout, is more deprecated than dynamic_lookup, and isn't supposed to even work in conda-forge. See also pybind/pybind11#4301 .
-undefined dynamic_lookup does silence the linker on missing symbols, that's what it's for. The problem is that the method it uses is deprecated, producing a warning (and already broken in iOS) -flat_namespace doesn't just silence the linker, it changes the binary layout for every symbol. You could always just silence the warning -Wl,-w or -Wl,-no_fixup_chains; this will eventually break, but is less deprecated than -flat_namespace.
Apple's official statement is basically "live with the warning for now, we'll find a way to not break all CPython extensions eventually" from what I gather.
@Axel-Naumann Axel-Naumann added this to the 6.28/00 milestone Dec 20, 2022
@Axel-Naumann Axel-Naumann self-assigned this Dec 20, 2022
@Axel-Naumann Axel-Naumann modified the milestones: 6.28/00, 6.26/12 Dec 20, 2022
Axel-Naumann added a commit to Axel-Naumann/root that referenced this issue Jan 17, 2023
@Axel-Naumann
Revert "[cmake] Xcode 14 warns about -undefined dynamic_lookup; sim…
351a0a0 
…ply suppress:"

See root-project#11937
for why `-flat_namespace` is bad.

This reverts commit a05d4be.
Axel-Naumann added a commit to Axel-Naumann/root that referenced this issue Jan 17, 2023
@Axel-Naumann
[cmake] Silence macOS linker warnings on -undefined dynamic_lookup:
060091c 
See root-project#11937
for why that is currently needed. `flat_namespace` is not a solution.
@Axel-Naumann Axel-Naumann mentioned this issue Jan 17, 2023
Merged
Axel-Naumann added a commit to Axel-Naumann/root that referenced this issue Jan 18, 2023
@Axel-Naumann
[cmake] Silence macOS linker warnings on -undefined dynamic_lookup:
fccb8de 
See root-project#11937
for why that is currently needed. `flat_namespace` is not a solution.
Axel-Naumann added a commit that referenced this issue Jan 19, 2023
@Axel-Naumann
Revert "[cmake] Xcode 14 warns about -undefined dynamic_lookup; sim…
0e03b6a 
…ply suppress:"

See #11937
for why `-flat_namespace` is bad.

This reverts commit a05d4be.
Axel-Naumann added a commit that referenced this issue Jan 19, 2023
@Axel-Naumann
[cmake] Silence macOS linker warnings on -undefined dynamic_lookup:
5ad4ab9 
See #11937
for why that is currently needed. `flat_namespace` is not a solution.
FonsRademakers pushed a commit to root-project/cling that referenced this issue Jan 19, 2023
@Axel-Naumann
Revert "[cmake] Xcode 14 warns about -undefined dynamic_lookup; sim…
0c98219 
…ply suppress:"

See root-project/root#11937
for why `-flat_namespace` is bad.

This reverts commit a05d4beded1481a86a65e450826352eb528b03e7.
FonsRademakers pushed a commit to root-project/cling that referenced this issue Jan 19, 2023
@Axel-Naumann
Silence macOS linker warnings on -undefined dynamic_lookup:
931552f 
See root-project/root#11937
for why that is currently needed. `flat_namespace` is not a solution.
@github-actions
Copy link

Hi @Axel-Naumann,

It appears this issue is closed, but wasn't yet added to a project. Please add upcoming versions that will include the fix, or 'not applicable' otherwise.

Sincerely,
🤖

Axel-Naumann added a commit to Axel-Naumann/root that referenced this issue Jan 23, 2023
@Axel-Naumann
Revert "[cmake] Xcode 14 warns about -undefined dynamic_lookup; sim…
330b4bc 
…ply suppress:"

See root-project#11937
for why `-flat_namespace` is bad.

This reverts commit a05d4be.

(cherry picked from commit 0e03b6a)
Axel-Naumann added a commit to Axel-Naumann/root that referenced this issue Jan 23, 2023
@Axel-Naumann
[cmake] Silence macOS linker warnings on -undefined dynamic_lookup:
571a83d 
See root-project#11937
for why that is currently needed. `flat_namespace` is not a solution.

(cherry picked from commit 5ad4ab9)
@Axel-Naumann Axel-Naumann mentioned this issue Jan 23, 2023
Merged
2 tasks
@github-actions
Copy link

Hi @Axel-Naumann,

It appears this issue is closed, but wasn't yet added to a project. Please add upcoming versions that will include the fix, or 'not applicable' otherwise.

Sincerely,
🤖

2 similar comments
@github-actions
Copy link

Hi @Axel-Naumann,

It appears this issue is closed, but wasn't yet added to a project. Please add upcoming versions that will include the fix, or 'not applicable' otherwise.

Sincerely,
🤖

@github-actions
Copy link

Hi @Axel-Naumann,

It appears this issue is closed, but wasn't yet added to a project. Please add upcoming versions that will include the fix, or 'not applicable' otherwise.

Sincerely,
🤖

@Axel-Naumann Axel-Naumann reopened this Jan 26, 2023
Axel-Naumann added a commit that referenced this issue Jan 27, 2023
@Axel-Naumann
Revert "[cmake] Xcode 14 warns about -undefined dynamic_lookup; sim…
a567664 
…ply suppress:"

See #11937
for why `-flat_namespace` is bad.

This reverts commit a05d4be.

(cherry picked from commit 0e03b6a)
Axel-Naumann added a commit that referenced this issue Jan 27, 2023
@Axel-Naumann
[cmake] Silence macOS linker warnings on -undefined dynamic_lookup:
23e406f 
See #11937
for why that is currently needed. `flat_namespace` is not a solution.

(cherry picked from commit 5ad4ab9)
@henryiii
Copy link
Contributor

Apple's solution was to default "no-fixup-chains" to on when undefined dynamic_lookup is passed; you can enable it for older versions to hide the warning as well, see pybind/pybind11#4301 (comment) and the linked CPython issue. Not sure yet if it causes issues for older versions that don't produce the warning in the first place.

omazapa pushed a commit to omazapa/root that referenced this issue Apr 13, 2023
@Axel-Naumann @omazapa
Revert "[cmake] Xcode 14 warns about -undefined dynamic_lookup; sim…
4cb4cf3 
…ply suppress:"

See root-project#11937
for why `-flat_namespace` is bad.

This reverts commit a05d4be.
omazapa pushed a commit to omazapa/root that referenced this issue Apr 13, 2023
@Axel-Naumann @omazapa
[cmake] Silence macOS linker warnings on -undefined dynamic_lookup:
ce50d45 
See root-project#11937
for why that is currently needed. `flat_namespace` is not a solution.
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Assignees

@Axel-Naumann Axel-Naumann

Labels
affects:master affects:6.26 bug in:Build System priority:critical
Projects
None yet
Milestone
6.28/00
Development

Successfully merging a pull request may close this issue.

Revert "[cmake] Xcode 14 warns about -undefined dynamic_lookup; simply suppress:" Axel-Naumann/root
2 participants
@Axel-Naumann @henryiii