New libclang dependency!

[Hoverbear]

Heads up! A recent change introduced a new libclang build time dependency. I had to add libclang after updating Vector from 0.6.1 to the master.

In 0.6.1 I did not need libclang so this seems like a new undocumented dependency and @iximeow said I should open an issue. :)

    Checking wabt v0.9.2
error: failed to run custom build command for `userfaultfd-sys v0.2.0`

Caused by:
  process didn't exit successfully: `/git/timberio/vector/target/debug/build/userfaultfd-sys-f6b2cf3cce5b4db1/build-script-build` (exit code: 101)
--- stderr
thread 'main' panicked at 'Unable to find libclang: "couldn\'t find any valid shared libraries matching: [\'libclang.so\', \'libclang-*.so\', \'libclang.so.*\'], set the `LIBCLANG_PATH` environment variable to a path where one of these files can be found (invalid: [])"', /home/hoverbear/.cargo/registry/src/github.com-1ecc6299db9ec823/bindgen-0.51.1/src/lib.rs:1731:13
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

warning: build failed, waiting for other jobs to finish...
error: build failed

I found in this checkout: https://github.com/timberio/vector/tree/f13723d4a8d82c164150fa78e0167c9e92c334c3

After applying this diff:

vector on  wasm-engine [$!?] is 📦 v0.9.1 via 🦀 v1.43.0 via ❄️  impure 
❯ git diff
diff --git a/default.nix b/default.nix
index 03634999..77917307 100644
--- a/default.nix
+++ b/default.nix
@@ -32,7 +32,7 @@ pkgs.buildEnv {
         ref = "refs/heads/nixpkgs-unstable";
         rev = "f61b3e02c05d36c58cb5f5fc793c38df5a79e490";
       }) {}).wabt
-      llvmPackages.libclang
+      # llvmPackages.libclang
     ]  ++ stdenv.lib.optional stdenv.isDarwin [ Security libiconv ];
     passthru = {
         shellHook = ''
@@ -42,7 +42,7 @@ pkgs.buildEnv {
             export LC_ALL="en_US.UTF-8";
             export OPENSSL_DIR="${pkgs.openssl.dev}";
             export OPENSSL_LIB_DIR="${pkgs.openssl.out}/lib";
-            export LIBCLANG_PATH ="${pkgs.llvmPackages.libclang}/lib";
+            # export LIBCLANG_PATH ="${pkgs.llvmPackages.libclang}/lib";
         '';
         PROTOC="${pkgs.protobuf}/bin/protoc";
         PROTOC_INCLUDE="${pkgs.protobuf}/include";
@@ -50,6 +50,6 @@ pkgs.buildEnv {
         LC_ALL="en_US.UTF-8";
         OPENSSL_DIR="${pkgs.openssl.dev}";
         OPENSSL_LIB_DIR="${pkgs.openssl.out}/lib";
-        LIBCLANG_PATH ="${pkgs.llvmPackages.libclang}/lib";
+        # LIBCLANG_PATH ="${pkgs.llvmPackages.libclang}/lib";
     };
 }
diff --git a/shell.nix b/shell.nix
index f31d0171..17c971ac 100644
--- a/shell.nix
+++ b/shell.nix
@@ -10,5 +10,5 @@ pkgs.mkShell {
   buildInputs = [ (import ./default.nix { inherit pkgs; }) ];
   OPENSSL_DIR="${pkgs.openssl.dev}";
   OPENSSL_LIB_DIR="${pkgs.openssl.out}/lib";
-  LIBCLANG_PATH ="${pkgs.llvmPackages.libclang}/lib";
+  # LIBCLANG_PATH ="${pkgs.llvmPackages.libclang}/lib";
 }

If you checkout https://github.com/timberio/vector/tree/1d88625ce5c35708a42d612c7abc6b4087676f78 then run the same shell build, it'll work since 0.6.1 didn't need libclang. :)

[iximeow]

for context/flavor: my suspicion is that we happened to not notice this in, say, testing, because our tests are run with clang-6.0 installed for fuzz bitrot testing in the first place. So we should probably verify that being the case or not and see if we need to update installation/Getting Started docs appropriately.

[williamoverton]

I've just ran into this issue after following these docs: https://bytecodealliance.github.io/lucet/Compiling-on-Linux.html

They seem to state that llvm and clang will be installed for you but I had to install them myself.