Substrate: cargo build -> librocksdb-sys v5.14.2 -> unable to find libclang ... libclang.so

[drandreaskrueger]

summary of the problem:

cargo build -> librocksdb-sys v5.14.2 -> Unable to find libclang ... libclang.so

what I did:

git clone https://github.com/paritytech/substrate.git paritytech_substrate
cd paritytech_substrate/
git checkout v0.9.2

./scripts/init.sh
./scripts/build.sh
cargo build

about git checkout v0.9.2 see https://github.com/paritytech/substrate/issues/3066

system is Debian 9

uname -a; rustc --version
Linux ... 4.9.0-9-amd64 #1 SMP Debian 4.9.168-1+deb9u3 (2019-06-16) x86_64 GNU/Linux
rustc 1.36.0 (a53f9df32 2019-07-03)

details:

cargo build
[...]

Compiling librocksdb-sys v5.14.2
error: failed to run custom build command for `librocksdb-sys v5.14.2`

Caused by:
  process didn't exit successfully: `~/paritytech_substrate/target/debug/build/librocksdb-sys-a0f791c907b0f400/build-script-build` (exit code: 101)
--- stdout
cargo:rerun-if-changed=build.rs
cargo:rerun-if-changed=rocksdb/
cargo:rerun-if-changed=snappy/

--- stderr
thread 'main' panicked at 'Unable to find libclang: "couldn\'t find any of [\'libclang.so\', \'libclang.so.*\', \'libclang-*.so\'], set the LIBCLANG_PATH environment variable to a path where one of these files can be found (skipped: [])"', src/libcore/result.rs:999:5
note: Run with `RUST_BACKTRACE=1` environment variable to display a backtrace.

warning: build failed, waiting for other jobs to finish...
warning: unused import: `ConstructRuntimeApi`
  --> core/client/src/client.rs:33:51
   |
33 | use runtime_api::{Core as CoreAPI, CallRuntimeAt, ConstructRuntimeApi};
   |                                                   ^^^^^^^^^^^^^^^^^^^

warning: variable does not need to be mutable
   --> core/client/src/client.rs:578:9
    |
578 |                 let mut r = self.executor.call_at_state(
    |                     ----^
    |                     |
    |                     help: remove this `mut`
    |
    = note: #[warn(unused_mut)] on by default

warning: static variable `__CacheGetByteStructAccountNonce` should have an upper case name
   --> srml/system/src/lib.rs:187:7
    |
187 |         pub AccountNonce get(account_nonce): map T::AccountId => T::Index;
    |             ^^^^^^^^^^^^ help: convert the identifier to upper case: `__CACHE_GET_BYTE_STRUCT_ACCOUNT_NONCE`
    |
    = note: #[warn(non_upper_case_globals)] on by default

warning: static variable `__CacheGetByteStructExtrinsicCount` should have an upper case name
   --> srml/system/src/lib.rs:189:3
    |
189 |         ExtrinsicCount: Option<u32>;
    |         ^^^^^^^^^^^^^^ help: convert the identifier to upper case: `__CACHE_GET_BYTE_STRUCT_EXTRINSIC_COUNT`

warning: static variable `__CacheGetByteStructBlockHash` should have an upper case name
   --> srml/system/src/lib.rs:190:7
    |
190 |         pub BlockHash get(block_hash) build(|_| vec![(T::BlockNumber::zero(), [69u8; 32])]): map T::BlockNumber => T::Hash;
    |             ^^^^^^^^^ help: convert the identifier to upper case: `__CACHE_GET_BYTE_STRUCT_BLOCK_HASH`

warning: static variable `__CacheGetByteStructExtrinsicData` should have an upper case name
   --> srml/system/src/lib.rs:191:3
    |
191 |         ExtrinsicData get(extrinsic_data): map u32 => Vec<u8>;
    |         ^^^^^^^^^^^^^ help: convert the identifier to upper case: `__CACHE_GET_BYTE_STRUCT_EXTRINSIC_DATA`

warning: static variable `__CacheGetByteStructRandomSeed` should have an upper case name
   --> srml/system/src/lib.rs:192:3
    |
192 |         RandomSeed get(random_seed) build(|_| [0u8; 32]): T::Hash;
    |         ^^^^^^^^^^ help: convert the identifier to upper case: `__CACHE_GET_BYTE_STRUCT_RANDOM_SEED`

warning: static variable `__CacheGetByteStructNumber` should have an upper case name
   --> srml/system/src/lib.rs:194:3
    |
194 |         Number get(block_number) build(|_| 1u64): T::BlockNumber;
    |         ^^^^^^ help: convert the identifier to upper case: `__CACHE_GET_BYTE_STRUCT_NUMBER`

warning: static variable `__CacheGetByteStructParentHash` should have an upper case name
   --> srml/system/src/lib.rs:195:3
    |
195 |         ParentHash get(parent_hash) build(|_| [69u8; 32]): T::Hash;
    |         ^^^^^^^^^^ help: convert the identifier to upper case: `__CACHE_GET_BYTE_STRUCT_PARENT_HASH`

warning: static variable `__CacheGetByteStructExtrinsicsRoot` should have an upper case name
   --> srml/system/src/lib.rs:196:3
    |
196 |         ExtrinsicsRoot get(extrinsics_root): T::Hash;
    |         ^^^^^^^^^^^^^^ help: convert the identifier to upper case: `__CACHE_GET_BYTE_STRUCT_EXTRINSICS_ROOT`

warning: static variable `__CacheGetByteStructDigest` should have an upper case name
   --> srml/system/src/lib.rs:197:3
    |
197 |         Digest get(digest): T::Digest;
    |         ^^^^^^ help: convert the identifier to upper case: `__CACHE_GET_BYTE_STRUCT_DIGEST`

warning: static variable `__CacheGetByteStructEvents` should have an upper case name
   --> srml/system/src/lib.rs:199:3
    |
199 |         Events get(events): Vec<EventRecord<T::Event>>;
    |         ^^^^^^ help: convert the identifier to upper case: `__CACHE_GET_BYTE_STRUCT_EVENTS`

error: build failed

what is libclang, and why don't I have that?

locate libclang.so
/var/lib/flatpak/runtime/org.gnome.Sdk/x86_64/3.26/980d2621abd9214c354c9f1a40286d366d8687cfa4066eb21ccb5e7083df80fd/files/lib/libclang.so
/var/lib/flatpak/runtime/org.gnome.Sdk/x86_64/3.26/980d2621abd9214c354c9f1a40286d366d8687cfa4066eb21ccb5e7083df80fd/files/lib/libclang.so.4
/var/lib/flatpak/runtime/org.gnome.Sdk/x86_64/3.26/980d2621abd9214c354c9f1a40286d366d8687cfa4066eb21ccb5e7083df80fd/files/lib/libclang.so.4.0

so it's there, but deep inside flatpak.

What to do?

[drandreaskrueger]

was easy to fix:

 sudo apt-get install -y clang

I guess, that dependency was missing from some initialization file, perhaps your

./scripts/init.sh

?

[andresilva]

It's specified in the README (https://github.com/paritytech/substrate#6-building). Our scripts don't manage system dependencies.

[drandreaskrueger]

Thanks. Eventually I found it out myself anyways.

I suggest you add that info to this page then: https://substrate.dev/docs/en/getting-started/installing-substrate#manual-build ... that is what I was following, as part of the official instructions.

Oh, and yey, what a relief: I found a way to get rid of all those -for me- useless warnings:

RUSTFLAGS=-Awarnings cargo build

Anyways, thanks.

[andresilva]

Agreed it probably makes sense to be there. cc @shawntabrizi

[shawntabrizi]

Ack. In general, you should make sure all dependencies needed for your computer are installed using:

curl https://getsubstrate.io -sSf | bash -s -- --fast

If you want to see what it does, you can simply go to https://getsubstrate.io

[drandreaskrueger]

Yes, now I got it: cmake pkg-config libssl-dev git gcc build-essential clang libclang-dev

If you want to avoid redundancy, why not just put the same sentence "... want to see what it does ..." into the "Manual Build" chapter.

Thanks!