esp-alloc: extern crate alloc; can't find crate

[frederictobiasc]

Hi,

I'd like to use esp-alloc. However, I get the following compile error when trying to run the psram.rs example example.

error[E0463]: can't find crate for `alloc`
  --> src/main.rs:11:1
   |
11 | extern crate alloc;
   | ^^^^^^^^^^^^^^^^^^^ can't find crate

For more information about this error, try `rustc --explain E0463`.

Am I missing a feature here? The example only lists psram-2m.

[frederictobiasc]

I decided to create a new project using cargo generate esp-rs/esp-template and noticed, that there is a prompt regarding alloc.

So my old project missed a feature in .cargo/config.toml:

--- a/.cargo/config.toml
+++ b/.cargo/config.toml
@@ -13,4 +13,4 @@ rustflags = [
 target = "xtensa-esp32-none-elf"
 
 [unstable]
-build-std = ["core"]
+build-std = ["alloc","core"]