Ninja hangs when I try to build

I tried my first build after switching to origin main. I did the switch by renaming my master branch and then pointing it at origin main.

I just tried to build llvm-tblgen. It fails building RandomNumberGenerator.cpp.obj with "C1902: Program database manager mismatch; please check your installation" Then it hangs; Ctrl+C does nothing.

I killed the window and started it up again. This time I tried a full build. It hangs building DebugCounter.cpp.obj.

I'm running Visual Studio 2019 on Windows 7. Has anyone else seen this?

The program database manager is a separate process VS uses to compile debug info into a PDB. The error happens when it’s trying to update a PDB that was created (or last modified) by a newer version of the PDB manager.

I suspect you have more than one version of VS installed.

I would close all instances of Visual Studio, check your environment to ensure that your build is set up to use the specific version you’re expecting, and make sure there are no lingering processes running mspdbsrv.exe, and then try again. If the problem recurs after that, I’d repeat but also delete the PDB files in question and force the compiler to rebuild them from scratch.

Thank you! I killed mspdbsrv and things got much further. Now I'm getting the usual message about switching from the 32-bit to the 64-bit linker, and then an "Unexpected PDB error; RPC (23)" message. This has been going on for awhile.

Is there an easy way to turn off PDB creation?

Sorry, I’m not familiar with “the usual message about switching from the 32-bit to the 64-bit linker.” Can you elaborate?

Is there an easy way to turn off PDB creation?

Probably, but I don’t know it offhand. The MS linker is going to produce a PDB by default if /DEBUG is specified, and it’s pretty common to generate them for “release” builds as well.

My guess is that you’re building multiple configurations at once, and different configurations (e.g., 32- and 64-bit, or debug and release) are trying to write their own PDBs to the same file name. I generally only build one configuration at a time, and I use ninja (even with MSVC) rather than the Visual Studio solution. Off the top of my head, exactly where the Cmake-generated build configurations try to place the PDBs.

I think the linker message occurs because Paul is compiling a 32-bit target (x86). When the 32-bit linker is out-of-space it automatically falls back to the 64-bit linker (x64), thus the message.

Paul, there are several options here. You could perhaps use the 64-bit target instead? Such as:

mkdir buildVS && cd buildVS

cmake -G"Visual Studio 16 2019" -Thost=x64 …/llvm (your other cmake options)

The default scenario you’re seeing is cl.exe using /Zi which offloads the PDB generation to mspdbsrv.exe. Since the LLVM libs are quite big, something in there might be running out of memory in a 32-bit process. You should be fine if switching to 64-bit host processes.

Another option is to build with Clang instead of MSVC in which case /Zi is like /Z7.

There’s already LLVM 10.0 embedded into Visual Studio (ensure it is installed through the VS Installer, click Modify):

cmake -G “Visual Studio 16 2019” -TClangCL …/llvm (your other cmake options)

Or download & install the LLVM 11.0 release (and install the “llvm2019” extension in Visual Studio: Extensions menu, Manage Extensions, click “Online” on the left, and use the search box):

cmake -G “Visual Studio 16 2019” -Tllvm …/llvm (your other cmake options)

Another other option is to create a secondary build folder and use ninja for building, and VS for editing & debugging. This is the best in terms of iteration times I would say.

To use MSVC & Ninja you would do:

mkdir buildninja && cd buildninja


ninja check-all

Or if you want to use LLVM 11.0 & Ninja:

cmake -G Ninja …/llvm -DCMAKE_BUILD_TYPE=Debug -DLLVM_OPTIMIZED_TABLEGEN=ON -DCMAKE_C_COMPILER=”C:/Program Files/LLVM/bin/clang-cl.exe” -DCMAKE_CXX_COMPILER=”C:/Program Files/LLVM/bin/clang-cl.exe” -DCMAKE_LINKER=”C:/Program Files/LLVM/bin/lld-link.exe” -DLLVM_ENABLE_PROJECTS=“clang;lld;llvm” -DLLVM_ENABLE_ASSERTIONS=ON -DLLVM_ENABLE_LIBXML2=OFF

Important - ensure all the above commands run in a Visual Studio cmd prompt, by first launching “x64 Native Tools Command Prompt for VS 2019” from your start menu.


Envoyé : December 8, 2020 5:14 PM

The 32-bit linker runs out of heap and something (Ninja?) switches to the 64-bit linker.

I'm not sure what you mean by building multiple configurations at once. I'm new here. :wink: I am using Ninja to do the build, which builds just one configuration, I assume.

I deleted all the PDB files and the build finished. I need to do some more research.

I currently build with Ninja, having run cmake as follows:


I just added -Thost=x64 to that command and got this:

CMake Error: Error: generator toolset: host=x64
Does not match the toolset used previously:
Either remove the CMakeCache.txt file and CMakeFiles directory or choose a different binary directory.

Shall I just go ahead and follow those instructions?

Forgive my lack of knowledge; this is all new to me.

No worries - yes please, delete the build folder and re-create it, you should be fine.

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