-C default-linker-libraries breaks the build at link time (pthread multiple symbols) with recent ESP IDF toolchains

[ivmarkov]

Also see this.

Need to get to the bottom of this but the most likely hypothesis is as per the comment above. It does happen at least with riscv targets, and with ESP IDF 5.X. Unsure yet if xtensa targets are affected, or any targets with ESP IDF 4.4.

WORKAROUND: Remove -C default-linker-libraries from .cargo/config.toml.

[ivmarkov]

Seems to me that linking to libnosys.a is the culprit.

[ivmarkov]

Digging a bit further: seems that the problem is with ESP IDF's own fork of newlib. Specifically, this thing: espressif/newlib-esp32@ff0b7d9

Still need to understand
(a) why this code was necessary in the first place - perhaps - to fill in the gaps in ESP IDF's own pthread implementation?
(b) why it does not link with weak syms
(c) why it does break only when default-linker-libraries is used

[mrchantey]

fyi in my case after removing -C default-linker-libraries I got all kinds of errors when trying to use esp_idf_svc 0.47.3 features like wifi. All good after doing a full clean including removing .embuild, then updating dependencies.

My current dependencies are working and look like this:

#[dependencies]
embedded-svc = "0.27"
embedded-hal = "1.0.0"
esp-idf-hal = "0.43"
esp-idf-svc = { version = "0.48", default-features = false,features = ["std"] }