FP `no method on type` impl super::Trait for super::Struct

The following code

trait Trait<T> {
    fn method(&self) {
        println!("method for {}", std::any::type_name::<T>());
    }
}

struct Foo;

fn _nested_mod_trait() {
    mod func_inner {
        pub(super) struct Nested;
        impl super::Trait<Nested> for super::Foo {}
    }
}

fn main() {
    Foo.method()
}

comiled with rustc (cargo check):

    Checking _snippet_706 v0.1.0 (/tmp/icemaker_global_tempdir.Te0xd0qSST2p/rustc_testrunner_tmpdir.HcNwnaeEZEXF/_snippet_706)
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.21s

but errors were issued by rust-analyzer diagnostics

at crate _snippet_706, file /tmp/icemaker_global_tempdir.Te0xd0qSST2p/rustc_testrunner_tmpdir.HcNwnaeEZEXF/_snippet_706/src/main.rs: Error RustcHardError("E0599") from LineCol { line: 16, col: 8 } to LineCol { line: 16, col: 14 }: no method `method` on type `Foo`

diagnostic scan complete


Error: diagnostic error detected

Stack backtrace:
   0: <anyhow::Error>::msg::<&str>
             at /home/matthias/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/anyhow-1.0.102/src/backtrace.rs:10:14
   1: anyhow::__private::format_err
             at /home/matthias/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/anyhow-1.0.102/src/lib.rs:687:13
   2: <rust_analyzer::cli::flags::Diagnostics>::run_
             at /home/matthias/vcs/github/rust-analyzer/crates/rust-analyzer/src/cli/diagnostics.rs:123:13
   3: <rust_analyzer::cli::flags::Diagnostics>::run::{closure#0}
             at /home/matthias/vcs/github/rust-analyzer/crates/rust-analyzer/src/cli/diagnostics.rs:20:29
   4: <stdx::thread::Builder>::spawn::<<rust_analyzer::cli::flags::Diagnostics>::run::{closure#0}, core::result::Result<(), anyhow::Error>>::{closure#0}
             at /home/matthias/vcs/github/rust-analyzer/crates/stdx/src/thread.rs:74:13
   5: std::sys::backtrace::__rust_begin_short_backtrace::<<stdx::thread::Builder>::spawn<<rust_analyzer::cli::flags::Diagnostics>::run::{closure#0}, core::result::Result<(), anyhow::Error>>::{closure#0}, core::result::Result<(), anyhow::Error>>
             at /home/matthias/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/sys/backtrace.rs:166:18
   6: std::thread::lifecycle::spawn_unchecked::<<stdx::thread::Builder>::spawn<<rust_analyzer::cli::flags::Diagnostics>::run::{closure#0}, core::result::Result<(), anyhow::Error>>::{closure#0}, core::result::Result<(), anyhow::Error>>::{closure#1}::{closure#0}
             at /home/matthias/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/thread/lifecycle.rs:70:13
   7: <core::panic::unwind_safe::AssertUnwindSafe<std::thread::lifecycle::spawn_unchecked<<stdx::thread::Builder>::spawn<<rust_analyzer::cli::flags::Diagnostics>::run::{closure#0}, core::result::Result<(), anyhow::Error>>::{closure#0}, core::result::Result<(), anyhow::Error>>::{closure#1}::{closure#0}> as core::ops::function::FnOnce<()>>::call_once
             at /home/matthias/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/panic/unwind_safe.rs:275:9
   8: std::panicking::catch_unwind::do_call::<core::panic::unwind_safe::AssertUnwindSafe<std::thread::lifecycle::spawn_unchecked<<stdx::thread::Builder>::spawn<<rust_analyzer::cli::flags::Diagnostics>::run::{closure#0}, core::result::Result<(), anyhow::Error>>::{closure#0}, core::result::Result<(), anyhow::Error>>::{closure#1}::{closure#0}>, core::result::Result<(), anyhow::Error>>
             at /home/matthias/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/panicking.rs:576:43
   9: std::panicking::catch_unwind::<core::result::Result<(), anyhow::Error>, core::panic::unwind_safe::AssertUnwindSafe<std::thread::lifecycle::spawn_unchecked<<stdx::thread::Builder>::spawn<<rust_analyzer::cli::flags::Diagnostics>::run::{closure#0}, core::result::Result<(), anyhow::Error>>::{closure#0}, core::result::Result<(), anyhow::Error>>::{closure#1}::{closure#0}>>
             at /home/matthias/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/panicking.rs:544:19
  10: std::panic::catch_unwind::<core::panic::unwind_safe::AssertUnwindSafe<std::thread::lifecycle::spawn_unchecked<<stdx::thread::Builder>::spawn<<rust_analyzer::cli::flags::Diagnostics>::run::{closure#0}, core::result::Result<(), anyhow::Error>>::{closure#0}, core::result::Result<(), anyhow::Error>>::{closure#1}::{closure#0}>, core::result::Result<(), anyhow::Error>>
             at /home/matthias/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/panic.rs:359:14
  11: std::thread::lifecycle::spawn_unchecked::<<stdx::thread::Builder>::spawn<<rust_analyzer::cli::flags::Diagnostics>::run::{closure#0}, core::result::Result<(), anyhow::Error>>::{closure#0}, core::result::Result<(), anyhow::Error>>::{closure#1}
             at /home/matthias/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/thread/lifecycle.rs:68:26
  12: <std::thread::lifecycle::spawn_unchecked<<stdx::thread::Builder>::spawn<<rust_analyzer::cli::flags::Diagnostics>::run::{closure#0}, core::result::Result<(), anyhow::Error>>::{closure#0}, core::result::Result<(), anyhow::Error>>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
             at /home/matthias/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ops/function.rs:250:5
  13: <alloc::boxed::Box<dyn core::ops::function::FnOnce<(), Output = ()> + core::marker::Send> as core::ops::function::FnOnce<()>>::call_once
             at /rustc/1a98b1e135b254f209c67d447b6d8bcd56a859e0/library/alloc/src/boxed.rs:2318:9
  14: <std::sys::thread::unix::Thread>::new::thread_start
             at /rustc/1a98b1e135b254f209c67d447b6d8bcd56a859e0/library/std/src/sys/thread/unix.rs:123:17
  15: <unknown>
  16: <unknown>

version information

rust-analyzer 0.0.0 (352d11db5c 2026-08-08)

Start with the reproduction in the issue and compare cargo check with the rust-analyzer diagnostics command. Inspect crates/rust-analyzer/src/cli/diagnostics.rs, which appears in the reported stack trace, then trace how the nested impl is resolved. Done means rust-analyzer no longer reports a false E0599 for Foo.method().