`-Z terminal-width` should account for compiler-generated text, not just user-supplied text

[shepmaster]

With source code with a long line (64 columns) but that is less than the chosen width (80 columns):

fn main() {
    a_very_long_function_name_that_pushes(and_then_an_argument);
}

fn a_very_long_function_name_that_pushes<T>(_: T) {}

The error message produced by rustc exceeds (90 columns) the width:

% rustc +nightly long.rs -Z terminal-width=80
error[E0425]: cannot find value `and_then_an_argument` in this scope
 --> long.rs:2:43
  |
2 |     a_very_long_function_name_that_pushes(and_then_an_argument);
  |                                           ^^^^^^^^^^^^^^^^^^^^ not found in this scope

/cc #84673

[ehuss]

I think it would be nice if the diagnostic system could world-wrap text in general. For example:

could be rendered something like:

error: incremental compilation: could not create session directory lock file:
       Operation not supported (os error 45)
  |
  = note: the filesystem for the incremental path at
          /Volumes/home/Temp/a/target/debug/incremental/a-2ayqbks3yzri8/s-gb4y1p66hp-to8nz4-working
          does not appear to support locking, consider changing the
          incremental path to a filesystem that supports locking or disable
          incremental compilation
  = help: incremental compilation can be disabled by setting the environment
          variable CARGO_INCREMENTAL=0 (see
          https://doc.rust-lang.org/cargo/reference/profiles.html#incremental)
  = help: the entire build directory can be changed to a different filesystem
          by setting the environment variable CARGO_TARGET_DIR to a different
          path (see
          https://doc.rust-lang.org/cargo/reference/config.html#buildtarget-dir)