Cannot compile contract with rust stable (cosmwasm master)

[webmaster128]

After upgrading cosmwasm and cosmwasm-vm in my contract with

diff --git a/erc20/Cargo.lock b/erc20/Cargo.lock
index 976eba7..a6f2ed3 100644
--- a/erc20/Cargo.lock
+++ b/erc20/Cargo.lock
@@ -161,8 +161,8 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "cosmwasm"
-version = "0.5.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
+version = "0.5.2"
+source = "git+https://github.com/confio/cosmwasm?rev=a7e02c8b77f472906bb2b92c2c0406c7b01b751f#a7e02c8b77f472906bb2b92c2c0406c7b01b751f"
 dependencies = [
  "schemars 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.103 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -172,10 +172,10 @@ dependencies = [
 
 [[package]]
 name = "cosmwasm-vm"
-version = "0.5.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
+version = "0.5.2"
+source = "git+https://github.com/confio/cosmwasm?rev=a7e02c8b77f472906bb2b92c2c0406c7b01b751f#a7e02c8b77f472906bb2b92c2c0406c7b01b751f"
 dependencies = [
- "cosmwasm 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "cosmwasm 0.5.2 (git+https://github.com/confio/cosmwasm?rev=a7e02c8b77f472906bb2b92c2c0406c7b01b751f)",
  "hex 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "lru 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "memmap 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -327,8 +327,8 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 name = "erc20"
 version = "0.1.0"
 dependencies = [
- "cosmwasm 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "cosmwasm-vm 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "cosmwasm 0.5.2 (git+https://github.com/confio/cosmwasm?rev=a7e02c8b77f472906bb2b92c2c0406c7b01b751f)",
+ "cosmwasm-vm 0.5.2 (git+https://github.com/confio/cosmwasm?rev=a7e02c8b77f472906bb2b92c2c0406c7b01b751f)",
  "hex 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "schemars 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde 1.0.103 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1157,8 +1157,8 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum const-random 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)" = "7b641a8c9867e341f3295564203b1c250eb8ce6cb6126e007941f78c4d2ed7fe"
 "checksum const-random-macro 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)" = "c750ec12b83377637110d5a57f5ae08e895b06c4b16e2bdbf1a94ef717428c59"
 "checksum constant_time_eq 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)" = "995a44c877f9212528ccc74b21a232f66ad69001e40ede5bcee2ac9ef2657120"
-"checksum cosmwasm 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)" = "421795f63fb6b5b176ff9c0147d04eab4b450b3af3b9f058f9d5ee4acaff2c2b"
-"checksum cosmwasm-vm 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)" = "82682509b316b6d033b240fcbdbc647c39c2ab85453a2bea8765f2e4187a430c"
+"checksum cosmwasm 0.5.2 (git+https://github.com/confio/cosmwasm?rev=a7e02c8b77f472906bb2b92c2c0406c7b01b751f)" = "<none>"
+"checksum cosmwasm-vm 0.5.2 (git+https://github.com/confio/cosmwasm?rev=a7e02c8b77f472906bb2b92c2c0406c7b01b751f)" = "<none>"
 "checksum cranelift-bforest 0.44.0 (registry+https://github.com/rust-lang/crates.io-index)" = "fff04f4ad82c9704a22e753c6268cc6a89add76f094b837cefbba1c665411451"
 "checksum cranelift-codegen 0.44.0 (registry+https://github.com/rust-lang/crates.io-index)" = "6ff4a221ec1b95df4b1d20a99fec4fe92a28bebf3a815f2eca72b26f9a627485"
 "checksum cranelift-codegen-meta 0.44.0 (registry+https://github.com/rust-lang/crates.io-index)" = "dd47f665e2ee8f177b97d1f5ce2bd70f54d3b793abb26d92942bfaa4a381fe9f"
diff --git a/erc20/Cargo.toml b/erc20/Cargo.toml
index d1fd543..96578e1 100644
--- a/erc20/Cargo.toml
+++ b/erc20/Cargo.toml
@@ -28,7 +28,7 @@ cranelift = [ "cosmwasm-vm/default-cranelift"]
 singlepass = [ "cosmwasm-vm/default-singlepass"]
 
 [dependencies]
-cosmwasm = { version = "0.5.1" }
+cosmwasm = { git = "https://github.com/confio/cosmwasm", rev = "a7e02c8b77f472906bb2b92c2c0406c7b01b751f" }
 schemars = "0.5"
 serde = { version = "1.0.60", default-features = false, features = ["derive"] }
 snafu = { version = "0.5.0", default-features = false, features = ["rust_1_30"] }
@@ -38,5 +38,5 @@ hex = "0.4.0"
 wasm-bindgen = "0.2"
 
 [dev-dependencies]
-cosmwasm-vm = { version = "0.5.1", default-features = false }
+cosmwasm-vm = { git = "https://github.com/confio/cosmwasm", rev = "a7e02c8b77f472906bb2b92c2c0406c7b01b751f" }
 serde_json = "1.0"

and adapting my code according to the API changes,

1. cargo build works
2. cargo wasm works
3. cargo unit-test fails to compile with

$ cargo unit-test
   Compiling dynasm v0.5.2
   Compiling wasmer-clif-fork-frontend v0.44.0
   Compiling cranelift-native v0.44.0
   Compiling wasmer-clif-fork-wasm v0.44.0
error[E0554]: `#![feature]` may not be used on the stable release channel
 --> /myhome/.cargo/registry/src/github.com-1ecc6299db9ec823/dynasm-0.5.2/src/lib.rs:1:1
  |
1 | #![feature(proc_macro_diagnostic)]
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error[E0554]: `#![feature]` may not be used on the stable release channel
 --> /myhome/.cargo/registry/src/github.com-1ecc6299db9ec823/dynasm-0.5.2/src/lib.rs:2:1
  |
2 | #![feature(proc_macro_span)]
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^

   Compiling wasmer-clif-backend v0.11.0
   Compiling wasmer-runtime v0.11.0
error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0554`.
error: could not compile `dynasm`.

where dynasm is known to work on rust nightly only.

There are two things I wonder:

1. Why does this error occur now, even if my dynasm and wasmer-singlepass-backend entries in erc20/Cargo.lock did not change.
2. Crate cosmwasm_vm is only used for integration tests. Why does the command cargo unit-test even need to compile it?

[webmaster128]

The dependency tree looks as expected

$ cargo tree -p dynasm -i
dynasm v0.5.2
└── wasmer-singlepass-backend v0.11.0
    └── cosmwasm-vm v0.5.2 (https://github.com/confio/cosmwasm?rev=a7e02c8b77f472906bb2b92c2c0406c7b01b751f#a7e02c8b)
        [dev-dependencies]
        └── erc20 v0.1.0 (/myhome/opensource/cosmwasm/cosmwasm-examples/erc20)

Is there any change in https://github.com/confio/cosmwasm/compare/v0.5.1...a7e02c8b77f472906bb2b92c2c0406c7b01b751f that adds wasmer-singlepass-backend as build requirement for the unit-tests?

[webmaster128]

I accidentally removed the , default-features = false } part of the cosmwasm-vm dependency during the upgrade. All good now :)

[ethanfrey]

Yeah, singlepass is the default for the production vm (gas metering), but I swap the defaults in the contracts for easier testing on stable. Gas metering is only a secondary concern there.

[ethanfrey]

Feel free to make this more explicit in the cosmwasm template repo if you think it will help others