Revert "Allow yeeting context selectors to generate errors"

This reverts commit d826e6a.

We found type inference regressions in the lead up to 0.8. This
feature doesn't pull its weight yet and is easiest to revert for
now. When `yeet` moves along, we can revisit.

See #431

.cirrus.yml

@@ -159,10 +159,6 @@ nightly_test_task:
     - cd compatibility-tests/backtrace-provider-api/
     - rustc --version
     - cargo test
-  yeet_selectors_test_script:
-    - cd compatibility-tests/yeet-selectors/
-    - rustc --version
-    - cargo test
   before_cache_script: rm -rf $CARGO_HOME/registry/index
 
 # Our Minimal Supported Rust Version (MSRV)

snafu-derive/src/shared.rs

@@ -294,16 +294,6 @@ pub mod context_selector {
                         ::core::result::Result::Err(self.build())
                     }
                 }
-
-                impl<#(#original_generics_without_defaults,)* #(#user_field_generics,)*> ::core::convert::From<#parameterized_selector_name> for #parameterized_error_name
-                where
-                    #(#extended_where_clauses),*
-                {
-                    #[track_caller]
-                    fn from(other: #parameterized_selector_name) -> Self {
-                        other.build()
-                    }
-                }
             }
         }
 

tests/build-leaf-error.rs

@@ -22,9 +22,3 @@ fn implements_error() {
 
     map_result().unwrap_err();
 }
-
-#[test]
-fn build_via_from_and_into() {
-    let _e = Error::from(MineSnafu);
-    let _e: Error = MineSnafu.into();
-}