MSVC: cannot link multiple staticlibs from the same workspace because of IMAGE_COMDAT_SELECT_NODUPLICATES

I tried: linking the GStreamer Rust plugins gstaws and gstrswebrtc, both built statically.

I expected to see this happen: linking success

Instead, this happened: some 5k lines of function clashes from shared dependencies e.g.:

libgstrswebrtc.a(gstrswebrtc.h2-9527afd107b48849.h2.4898c1e7831a741c-cgu.0.rcgu.o.rcgu.o) : error LNK2005: ya se definió _ZN102_$LT$core..iter..adapters..map..Map$LT$I$C$F$GT$$u20$as$u20$core..iter..traits..iterator..Iterator$GT$4fold17h30be9aebf26ab811E en libgstaws.a(gstaws.h2-9527afd107b48849.h2.4898c1e7831a741c-cgu.0.rcgu.o.rcgu.o)
libgstrswebrtc.a(gstrswebrtc.h2-9527afd107b48849.h2.4898c1e7831a741c-cgu.0.rcgu.o.rcgu.o) : error LNK2005: ya se definió _ZN111_$LT$core..iter..adapters..zip..Zip$LT$A$C$B$GT$$u20$as$u20$core..iter..adapters..zip..ZipImpl$LT$A$C$B$GT$$GT$3new17h21a4a1e578e1b030E en libgstaws.a(gstaws.h2-9527afd107b48849.h2.4898c1e7831a741c-cgu.0.rcgu.o.rcgu.o)

I believe this is caused by LLVM assuming IMAGE_COMDAT_SELECT_NODUPLICATES for all function COMDATS, which is too restrictive for MSVC: https://github.com/llvm/llvm-project/blob/llvmorg-20.1.5/llvm/lib/Transforms/Utils/Instrumentation.cpp#L102-L107.

This should perhaps be changed to IMAGE_COMDAT_SELECT_EXACT_MATCH on the Rust side; I tried it locally, but I got an impossibly long panic stacktrace which I attach below.

Meta

rustc --version --verbose:

rustc 1.87.0 (17067e9ac 2025-05-09)
binary: rustc
commit-hash: 17067e9ac6d7ecb70e50f92c1944e545188d2359
commit-date: 2025-05-09
host: x86_64-pc-windows-msvc
release: 1.87.0
LLVM version: 20.1.1

Backtrace: rustc-ice-2025-07-14T01_44_18-10920.txt

Reproduce the failure on x86_64-pc-windows-msvc by linking the statically built GStreamer Rust plugins gstaws and gstrswebrtc. Read LLVM's Instrumentation.cpp at the linked COMDAT-selection code, compare the attempted Rust-side change with the attached rustc ICE backtrace, and verify that linking succeeds without duplicate-symbol errors or a compiler panic.