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Rollup merge of #103706 - zbyrn:issue-101637-fix, r=estebank

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Fix E0433 No Typo Suggestions

Fixes #48676
Fixes #87791
Fixes #96625
Fixes #95462
Fixes #101637
Follows up PR #72923

Several open issues refer to the problem that E0433 does not suggest typos like other errors normally do. This fix augments the implementation of PR #72923.

**Background**
When the path of a function call, e.g. `Struct::foo()`, involves names that cannot be resolved, there are two errors that could be emitted by the compiler:
 - If `Struct` is not found, it is ``E0433: failed to resolve: use of undeclared type `Struct` ``.
 - If `foo` is not found in `Struct`, it is ``E0599: no function or associated item named `foo` found for struct `Struct` in the current scope``

When a name is used as a type, `e.g. fn foo() -> Struct`, and the name cannot be resolved, it is ``E0412: cannot find type `Struct` in this scope``.

Before #72923, `E0433` does not implement any suggestions, and the PR introduces suggestions for missing `use`s. When a resolution error occurs in the path of a function call, it tries to smart resolve just the type part of the path, e.g. `module::Struct` of a call to `module::Struct::foo()`. However, along with the suggestions, the smart-resolve function will report `E0412` since it only knows that it is a type that we cannot resolve instead of being a part of the path. So, the original implementation swap out `E0412` errors returned by the smart-resolve function with the real `E0433` error, but keeps the "missing `use`" suggestions to be reported to the programmer.

**Issue**
The current implementation only reports if there are "missing `use`" suggestions returned by the smart-resolve function; otherwise, it would fall back the normal reporting, which does not emit suggestions. But the smart-resolve function could also produce typo suggestions, which are omitted currently.

Also, it seems like that not all info has been swapped out when there are missing suggestions. The error message underlining the name in the snippet still says ``not found in this scope``, which is a `E0412` messages, if there are `use` suggestions, but says the normal `use of undeclared type` otherwise.

**Fixes**
This fix swaps out all fields in `Diagnostic` returned by the smart-resolve function except for `suggestions` with the current error, and merges the `suggestions` of the returned error and that of the current error together. If there are `use` suggestions, the error is saved to `use_injection` to be reported at the end; otherwise, the error is emitted immediately as `Resolver::report_error` does.

Some tests are updated to use the correct underlining error messages, and one additional test for typo suggestion is added to the test suite.

r? rust-lang/diagnostics
This commit is contained in:
Dylan DPC 2022-11-01 14:12:26 +05:30 • committed by GitHub
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12 changed files with 148 additions and 36 deletions
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54
compiler/rustc_resolve/src/late.rs
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@ -32,7 +32,7 @@ use smallvec::{smallvec, SmallVec};
use rustc_span::source_map::{respan, Spanned};
use std::assert_matches::debug_assert_matches;
use std::collections::{hash_map::Entry, BTreeSet};
use std::mem::{replace, take};
use std::mem::{replace, swap, take};
mod diagnostics;
@ -3369,11 +3369,6 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
let (mut err, candidates) =
this.smart_resolve_report_errors(path, path_span, PathSource::Type, None);
if candidates.is_empty() {
err.cancel();
return Some(parent_err);
}
// There are two different error messages user might receive at
// this point:
// - E0412 cannot find type `{}` in this scope
@ -3383,37 +3378,62 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
// latter one - for paths in expression-position.
//
// Thus (since we're in expression-position at this point), not to
// confuse the user, we want to keep the *message* from E0432 (so
// confuse the user, we want to keep the *message* from E0433 (so
// `parent_err`), but we want *hints* from E0412 (so `err`).
//
// And that's what happens below - we're just mixing both messages
// into a single one.
let mut parent_err = this.r.into_struct_error(parent_err.span, parent_err.node);
// overwrite all properties with the parent's error message
err.message = take(&mut parent_err.message);
err.code = take(&mut parent_err.code);
swap(&mut err.span, &mut parent_err.span);
err.children = take(&mut parent_err.children);
err.sort_span = parent_err.sort_span;
err.is_lint = parent_err.is_lint;
// merge the parent's suggestions with the typo suggestions
fn append_result<T, E>(res1: &mut Result<Vec<T>, E>, res2: Result<Vec<T>, E>) {
match res1 {
Ok(vec1) => match res2 {
Ok(mut vec2) => vec1.append(&mut vec2),
Err(e) => *res1 = Err(e),
},
Err(_) => (),
};
}
append_result(&mut err.suggestions, parent_err.suggestions.clone());
parent_err.cancel();
let def_id = this.parent_scope.module.nearest_parent_mod();
if this.should_report_errs() {
this.r.use_injections.push(UseError {
err,
candidates,
def_id,
instead: false,
suggestion: None,
path: path.into(),
is_call: source.is_call(),
});
if candidates.is_empty() {
// When there is no suggested imports, we can just emit the error
// and suggestions immediately. Note that we bypass the usually error
// reporting routine (ie via `self.r.report_error`) because we need
// to post-process the `ResolutionError` above.
err.emit();
} else {
// If there are suggested imports, the error reporting is delayed
this.r.use_injections.push(UseError {
err,
candidates,
def_id,
instead: false,
suggestion: None,
path: path.into(),
is_call: source.is_call(),
});
}
} else {
err.cancel();
}
// We don't return `Some(parent_err)` here, because the error will
// be already printed as part of the `use` injections
// be already printed either immediately or as part of the `use` injections
None
};