[SR-12939] Xcode 11.4: CGRPCZlib.o malformed object (string table at offset 0 with a size of 8, overlaps Mach-O headers at offset 0 with a size of 160)

[weissi]

Previous ID	SR-12939
Radar	rdar://problem/64023875
Original Reporter	@weissi
Type	Bug

Environment

Xcode 11.4/11.5beta

Additional Detail from JIRA

Votes	0
Component/s	Compiler
Labels	Bug
Assignee	None
Priority	Medium

md5: c4bbb39446bbe080a7969174c719d12f

Issue Description:

The contributor mRs- reported a very easy to reproduce failure of Xcode to compile gRPC Swift. This is a regression as it worked in 11.3.

The build produces at least two object files which fail with

CGRPCZlib.o malformed object (string table at offset 0 with a size of 8, overlaps Mach-O headers at offset 0 with a size of 160)

in otool, libtool, strings, ...

Repro:

1. clone https://github.com/mRs-/Xcode-11.4-Libtool-Regression
2. Product -> Archive

[weissi]

@swift-ci create

[weissi]

Thanks to @abertelrud I found a simple workaround: Just make the C files non-empty (useless symbol) in NIO & gRPC and everything compiles 🙂

[weissi]

workarounds in NIO & gRPC Swift:

• workaround SR-12939 grpc/grpc-swift#826

• workaround SR-12939 apple/swift-nio#1546