fail to use a no_std friendly dependence in smart contract

Question

I try to use barebones-x509 which is no_std friendly to parse x509 certificate. But encounter the mistake. Will you have some advice?

error: duplicate lang item in crate `std` (which `barebones_x509` depends on): `panic_impl`.                                                                                          
  |
  = note: the lang item is first defined in crate `ink_env` (which `blbc` depends on)
  = note: first definition in `ink_env` loaded from \\?\F:\CLIONproject\github\blbc\target\ink\wasm32-unknown-unknown\release\deps\libink_env-08ee0ee200503572.rlib, \\?\F:\CLIONproject\github\blbc\target\ink\wasm32-unknown-unknown\release\deps\libink_env-08ee0ee200503572.rmeta
  = note: second definition in `std` loaded from \\?\F:\CLIONproject\github\blbc\target\ink\wasm32-unknown-unknown\release\deps\libstd-5c2faf671e59e752.rlib, \\?\F:\CLIONproject\github\blbc\target\ink\wasm32-unknown-unknown\release\deps\libstd-5c2faf671e59e752.rmeta

error: duplicate lang item in crate `std` (which `barebones_x509` depends on): `oom`.
  |
  = note: the lang item is first defined in crate `ink_allocator` (which `ink_env` depends on)
  = note: first definition in `ink_allocator` loaded from \\?\F:\CLIONproject\github\blbc\target\ink\wasm32-unknown-unknown\release\deps\libink_allocator-3d57f925da559e39.rlib, \\?\F:\CLIONproject\github\blbc\target\ink\wasm32-unknown-unknown\release\deps\libink_allocator-3d57f925da559e39.rmeta
  = note: second definition in `std` loaded from \\?\F:\CLIONproject\github\blbc\target\ink\wasm32-unknown-unknown\release\deps\libstd-5c2faf671e59e752.rlib, \\?\F:\CLIONproject\github\blbc\target\ink\wasm32-unknown-unknown\release\deps\libstd-5c2faf671e59e752.rmeta

Answer 1

This is likely because you are not using the correct features for barebones-x509 in your Cargo.toml. To be sure you would have to post it.

I suspect that you are missing something like this:

@@ -11,6 +11,8 @@ ink = { path = "../../crates/ink", default-features = false }
 scale = { package = "parity-scale-codec", version = "3", default-features = false, features = ["derive"] }
 scale-info = { version = "2.3", default-features = false, features = ["derive"], optional = true }
 
+barebones-x509 = { version = "0.5.2", default-features = false }
+
 [dev-dependencies]
 ink_e2e = { path = "../../crates/e2e" }
 
@@ -25,6 +27,7 @@ std = [
     "ink/std",
     "scale/std",
     "scale-info/std",
+    "barebones-x509/std"
 ]
 ink-as-dependency = []

It's hard to tell though without knowing how you depend on the crate. Please post your Cargo.toml if it still doesn't work.