[llvm-dev] Code Coverage Compile Issue LLVM 10

[Fangrui Song via llvm-dev]

On 2020-09-09, Aaron via llvm-dev wrote:
>Hello,
>
>I recently updated LLVM from version 6.0.0 to 10.0.0.
>
>I see the following issue when I compile an application only with code
>coverage compiler options. Thes issue does not appear in any other build
>type.
>
>*...:(__llvm_prf_data[__profv__**ZNK4llvm3cfg6UpdateIPNS_**10BasicBlockEE4dumpEv]+0x18):
>**undefined reference to `llvm::cfg::Update<llvm::**BasicBlock*>::dump()
>const'*
>
>I see this issue only when I compile the app with the following compiler
>options:
>
>*-g -O2 -fprofile-instr-generate -fcoverage-mapping*
>
>I don't use any special flags when I build LLVM. I used g++-7 (or
>clang++-9) to compile LLVM static libs. The issue does not appear with LLVM
>6.0.0.
>
>I included all LLVM libraries in the same order whatever *llvm-config
>--libs *outputs.
>
>What lib am I missing? Or is this a known issue?
>
>Thank you,
>Aaron

llvm::cfg::Update<llvm::**BasicBlock*>::dump() is guarded by 
!defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)

I cannot find anywhere it is referenced.
It seems that you call this function but do not provide the definition.