no-std compilation breaks if target actually doesn't have std

[lvella]

Tried to build with all features disabled ("std" among them) for target riscv32imc-unknown-none-elf, which actually doesn't have std, and compilation fails in many libraries that does require std.

I may be missing something, but I don't think there is a point in having a library supporting #![no-std] if their mandatory dependencies are only available on std-enabled targets, so I guess this is a bug?

[rakita]

tried it and it does fail.

All libs have no_std but for some reason the compiler does include core traits by default.

Do you have maybe solution for this?

[rakita]

ruint does not have support for no_std, it is being worked on to support it.

[lvella]

I have spent some time trying to track down the origin of std dependency, and the following command was helpful:

cargo tree --target=riscv32imc-unknown-none-elf -e features,normal

It seems the libraries with std feature enabled were included by the dependency paths:

• revm-interpreter→revm-primitives→ruint→...
• revm-precompile→once_cell

Unfortunately this analysis relied on crates having an std feature. It sounds simple enough, but I couldn't find a command/tool to follow the dependency tree and actually tell if each library was built with #![no-std] or not.

[lvella]

It seems that ruint does have no-std support now.

[rakita]

It seems that ruint does have no-std support now.

Here is transition to alloy that uses newest ruint lib: #617

[rakita]

fixed in multiple transitions but last PR was this #669