Linking to rustc_llvm with --llvm-root

[Zoxc]

If you link to rustc_llvm with a rustc configured with --llvm-root the path to the LLVM libraries is not passed to the linker resulting in linking errors

[Zoxc]

There are no static libraries which depend on LLVM right? So there is no reason linking to rustc_plugin would require linking in LLVM libraries?

[Zoxc]

Linking to LLVM doesn't happen on OS X or debian, but it does on x86_64-mingw-w64 with msys2

[Zoxc]

@DiamondLovesYou Do you think this is related to #27937? I know this used to work on one of your earlier llvm-root-and-shared branches.

Linking errors:

   Compiling assembly v0.1.0 (file:///B:/Programmering/SandboxOS/AveryRust/kernel/arch/x64/multiboot)
error: linking with `gcc` failed: exit code: 1
note: "gcc" "-Wl,--enable-long-section-names" "-fno-use-linker-plugin" "-Wl,--nxcompat" "-nostdlib" "-m64" "B:\\Programmering\\SandboxOS\\AveryRust\\vendor\\rust\\install\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib\\dllcrt2.o" "B:\\Programmering\\SandboxOS\\AveryRust\\vendor\\rust\\install\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib\\rsbegin.o" "-L" "B:\\Programmering\\SandboxOS\\AveryRust\\vendor\\rust\\install\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib" "B:/Programmering/SandboxOS/AveryRust/build/cargo/target\\release\\deps\\assembly-bb6051f47b5bc242.0.o" "-o" "B:/Programmering/SandboxOS/AveryRust/build/cargo/target\\release\\deps\\assembly-bb6051f47b5bc242.dll" "B:/Programmering/SandboxOS/AveryRust/build/cargo/target\\release\\deps\\assembly-bb6051f47b5bc242.metadata.o" "-nodefaultlibs" "-L" "B:/Programmering/SandboxOS/AveryRust/build/cargo/target\\release\\deps" "-L" "B:/Programmering/SandboxOS/AveryRust/build/cargo/target\\release\\deps" "-L" "B:\\Programmering\\SandboxOS\\AveryRust\\vendor\\rust\\install\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib" "-Wl,-Bstatic" "-Wl,-Bdynamic" "-L" "B:\\Programmering\\SandboxOS\\AveryRust\\vendor\\rust\\install\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib" "-l" "rustc_plugin-ca1c970e" "-L" "B:\\Programmering\\SandboxOS\\AveryRust\\vendor\\rust\\install\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib" "-l" "rustc_metadata-ca1c970e" "-L" "B:\\Programmering\\SandboxOS\\AveryRust\\vendor\\rust\\install\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib" "-l" "rustc-ca1c970e" "-L" "B:\\Programmering\\SandboxOS\\AveryRust\\vendor\\rust\\install\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib" "-l" "rustc_data_structures-ca1c970e" "-L" "B:\\Programmering\\SandboxOS\\AveryRust\\vendor\\rust\\install\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib" "-l" "graphviz-ca1c970e" "-L" "B:\\Programmering\\SandboxOS\\AveryRust\\vendor\\rust\\install\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib" "-l" "fmt_macros-ca1c970e" "-L" "B:\\Programmering\\SandboxOS\\AveryRust\\vendor\\rust\\install\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib" "-l" "arena-ca1c970e" "-L" "B:\\Programmering\\SandboxOS\\AveryRust\\vendor\\rust\\install\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib" "-l" "getopts-ca1c970e" "-L" "B:\\Programmering\\SandboxOS\\AveryRust\\vendor\\rust\\install\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib" "-l" "flate-ca1c970e" "-L" "B:\\Programmering\\SandboxOS\\AveryRust\\vendor\\rust\\install\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib" "-l" "rustc_back-ca1c970e" "-L" "B:\\Programmering\\SandboxOS\\AveryRust\\vendor\\rust\\install\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib" "-l" "rustc_front-ca1c970e" "-L" "B:\\Programmering\\SandboxOS\\AveryRust\\vendor\\rust\\install\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib" "-l" "syntax-ca1c970e" "-L" "B:\\Programmering\\SandboxOS\\AveryRust\\vendor\\rust\\install\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib" "-l" "term-ca1c970e" "-L" "B:\\Programmering\\SandboxOS\\AveryRust\\vendor\\rust\\install\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib" "-l" "rustc_llvm-ca1c970e" "-L" "B:\\Programmering\\SandboxOS\\AveryRust\\vendor\\rust\\install\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib" "-l" "rbml-ca1c970e" "-L" "B:\\Programmering\\SandboxOS\\AveryRust\\vendor\\rust\\install\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib" "-l" "serialize-ca1c970e" "-L" "B:\\Programmering\\SandboxOS\\AveryRust\\vendor\\rust\\install\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib" "-l" "log-ca1c970e" "-L" "B:\\Programmering\\SandboxOS\\AveryRust\\vendor\\rust\\install\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib" "-l" "std-ca1c970e" "-l" "psapi" "-l" "kernel32" "-l" "ole32" "-l" "LLVMInterpreter" "-l" "LLVMMCJIT" "-l" "LLVMExecutionEngine" "-l" "LLVMRuntimeDyld" "-l" "LLVMipo" "-l" "LLVMVectorize" "-l" "LLVMLinker" "-l" "LLVMIRReader" "-l" "LLVMAsmParser" "-l" "LLVMX86Disassembler" "-l" "LLVMX86AsmParser" "-l" "LLVMX86CodeGen" "-l" "LLVMSelectionDAG" "-l" "LLVMAsmPrinter" "-l" "LLVMCodeGen" "-l" "LLVMTarget" "-l" "LLVMScalarOpts" "-l" "LLVMInstCombine" "-l" "LLVMInstrumentation" "-l" "LLVMProfileData" "-l" "LLVMTransformUtils" "-l" "LLVMBitWriter" "-l" "LLVMAnalysis" "-l" "LLVMX86Desc" "-l" "LLVMObject" "-l" "LLVMMCParser" "-l" "LLVMBitReader" "-l" "LLVMMCDisassembler" "-l" "LLVMX86Info" "-l" "LLVMX86AsmPrinter" "-l" "LLVMMC" "-l" "LLVMX86Utils" "-l" "LLVMCore" "-l" "LLVMSupport" "-l" "psapi" "-l" "shell32" "-l" "ole32" "-l" "uuid" "-l" "stdc++" "-l" "gcc_eh" "-l" "ws2_32" "-l" "userenv" "-l" "shell32" "-l" "advapi32" "-shared" "-l" "compiler-rt" "-lmingwex" "-lmingw32" "-lgcc" "-lmsvcrt" "-luser32" "-lkernel32" "B:\\Programmering\\SandboxOS\\AveryRust\\vendor\\rust\\install\\lib\\rustlib\\x86_64-pc-windows-gnu\\lib\\rsend.o"
note: X:/Programmer/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lLLVMInterpreter
X:/Programmer/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lLLVMMCJIT
X:/Programmer/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lLLVMExecutionEngine
X:/Programmer/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lLLVMRuntimeDyld
X:/Programmer/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lLLVMipo
X:/Programmer/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lLLVMVectorize
X:/Programmer/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lLLVMLinker
X:/Programmer/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lLLVMIRReader
X:/Programmer/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lLLVMAsmParser
X:/Programmer/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lLLVMX86Disassembler
X:/Programmer/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lLLVMX86AsmParser
X:/Programmer/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lLLVMX86CodeGen
X:/Programmer/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lLLVMSelectionDAG
X:/Programmer/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lLLVMAsmPrinter
X:/Programmer/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lLLVMCodeGen
X:/Programmer/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lLLVMTarget
X:/Programmer/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lLLVMScalarOpts
X:/Programmer/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lLLVMInstCombine
X:/Programmer/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lLLVMInstrumentation
X:/Programmer/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lLLVMProfileData
X:/Programmer/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lLLVMTransformUtils
X:/Programmer/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lLLVMBitWriter
X:/Programmer/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lLLVMAnalysis
X:/Programmer/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lLLVMX86Desc
X:/Programmer/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lLLVMObject
X:/Programmer/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lLLVMMCParser
X:/Programmer/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lLLVMBitReader
X:/Programmer/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lLLVMMCDisassembler
X:/Programmer/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lLLVMX86Info
X:/Programmer/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lLLVMX86AsmPrinter
X:/Programmer/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lLLVMMC
X:/Programmer/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lLLVMX86Utils
X:/Programmer/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lLLVMCore
X:/Programmer/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/5.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: cannot find -lLLVMSupport
collect2.exe: error: ld returned 1 exit status

[DiamondLovesYou]

@Zoxc The error you've provided is the result of a missing -L path, specifically the one pointing to where LLVM's *.libs are located. In the normal case w.r.t. Rust's linking model, LLVM is statically linked into librustc_llvm (meaning an -L path to LLVM libs isn't needed/expected); however when LLVM is dynamic Rust will try to transitively link all shared/dynamic dependencies. Meaning every crate and their downstream dependencies which use any part of rustc_llvm will have the LLVM *.libs added to their linker args.

Rust doesn't install any LLVM static or shared libraries (this includes MSVCs .lib files) into its target specific rustlibs folder (which, as you've discovered, is quite an issue for shared LLVM + MSVC Rust), let alone at all, which I bet is the underlying issue.

[Zoxc]

You should only transitively link to dependencies of a dependency if the immediate dependency is a a static library. rustc_llvm is shared so it does not need its dependencies to be linked.

[Zoxc]

Well there is the case were an upstream Rust shared library has generic code which links to a native library. So I guess the behavior is justified.

That means we have to ensure LLVM's lib path is passed to the linker with rustc_llvm. Can the metadata hold paths to libraries or do we need some other way of making this happen?

[DiamondLovesYou]

@Zoxc

That means we have to ensure LLVM's lib path is passed to the linker with rustc_llvm. Can the metadata hold paths to libraries or do we need some other way of making this happen?

Metadata should not hold paths to deps. The path must be provided by cargo or rustc.

[alexcrichton]

I believe in the transition to rustbuild everything about LLVM changed enough that this is either likely fixed or no longe relevant, so closing.

[Zoxc]

@alexcrichton I doubt that is true.