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cmd/link: linker fails on linux/amd64 when gcc's lto options are used [1.19 backport] #59050

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gopherbot opened this issue Mar 15, 2023 · 3 comments
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cmd/link: linker fails on linux/amd64 when gcc's lto options are used [1.19 backport] #59050

gopherbot opened this issue Mar 15, 2023 · 3 comments
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@thanm
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CherryPickApproved Used during the release process for point releases compiler/runtime Issues related to the Go compiler and/or runtime. FrozenDueToAge GoCommand cmd/go
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Go1.19.8

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@thanm requested issue #58619 to be considered for backport to the next 1.19 minor release.

@gopherbot please open backport issues
@gopherbot gopherbot added the CherryPickCandidate Used during the release process for point releases label Mar 15, 2023
@gopherbot gopherbot mentioned this issue Mar 15, 2023
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@gopherbot gopherbot added the compiler/runtime Issues related to the Go compiler and/or runtime. label Mar 15, 2023
@gopherbot gopherbot added this to the Go1.19.8 milestone Mar 15, 2023
@thanm thanm self-assigned this Mar 15, 2023
@thanm thanm added the GoCommand cmd/go label Mar 15, 2023
@cherrymui cherrymui added the CherryPickApproved Used during the release process for point releases label Mar 15, 2023
@gopherbot gopherbot removed the CherryPickCandidate Used during the release process for point releases label Mar 15, 2023
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cherrymui commented Mar 15, 2023 •
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For 1.19, it is less of a problem compared to 1.20 (where we stopped shipping binary package archives), but still can be a problem if user explicitly set C flags (e.g. via CGO_CFLAGS) that is not known to be internal linking compatible. In this case, it will switch to external linking. And that is safe because the user would already have a C toolchain (otherwise the C compilation would fail regardless of this change). Given that we support last two releases equally, it is fine to backport this to 1.19. Approved.

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Change https://go.dev/cl/476576 mentions this issue: [release-branch.go1.19] cmd/go,cmd/link: prefer external linking when strange cgo flags seen

gopherbot pushed a commit that referenced this issue Mar 17, 2023
@thanm @cherrymui
[release-branch.go1.19] cmd/go,cmd/link: prefer external linking when…
2094fd0 
… strange cgo flags seen

This patch changes the Go command to examine the set of compiler
flags feeding into the C compiler when packages that use cgo are built.
If any of a specific set of strange/dangerous flags are in use,
then the Go command generates a token file ("preferlinkext") and
embeds it into the compiled package's archive.

When the Go linker reads the archives of the packages feeding into the
link and detects a "preferlinkext" token, it will then use external
linking for the program by default (although this default can be
overridden with an explicit "-linkmode" flag).

The intent here is to avoid having to teach the Go linker's host object
reader to grok/understand the various odd symbols/sections/types that
can result from boutique flag use, but rather to just boot the objects
in question over to the C linker instead.

Fixes #59050.
Updates #58619.
Updates #58620.
Updates #58848.

Change-Id: I56382dd305de8dac3841a7a7e664277826061eaa
Reviewed-on: https://go-review.googlesource.com/c/go/+/475375
Reviewed-by: Cherry Mui <[email protected]>
Reviewed-by: Bryan Mills <[email protected]>
Run-TryBot: Than McIntosh <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
(cherry picked from commit 035db07)
Reviewed-on: https://go-review.googlesource.com/c/go/+/476576
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Closed by merging 2094fd0 to release-branch.go1.19.

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CherryPickApproved Used during the release process for point releases compiler/runtime Issues related to the Go compiler and/or runtime. FrozenDueToAge GoCommand cmd/go
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