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introduce future-compatibility warning for forbidden lint groups

We used to ignore `forbid(group)` scenarios completely. This changed
in #78864, but that led to a number of regressions (#80988, #81218).

This PR introduces a future compatibility warning for the case where
a group is forbidden but then an individual lint within that group
is allowed. We now issue a FCW when we see the "allow", but permit
it to take effect.
This commit is contained in:
Niko Matsakis 2021-01-29 19:06:00 -05:00
parent c0b64d97be
commit b6b897b02c
19 changed files with 554 additions and 54 deletions

View file

@ -5,7 +5,10 @@ use rustc_data_structures::fx::FxHashMap;
use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
use rustc_errors::{DiagnosticBuilder, DiagnosticId};
use rustc_hir::HirId;
use rustc_session::lint::{builtin, Level, Lint, LintId};
use rustc_session::lint::{
builtin::{self, FORBIDDEN_LINT_GROUPS},
Level, Lint, LintId,
};
use rustc_session::{DiagnosticMessageId, Session};
use rustc_span::hygiene::MacroKind;
use rustc_span::source_map::{DesugaringKind, ExpnKind, MultiSpan};
@ -89,7 +92,12 @@ impl LintLevelSets {
// If we're about to issue a warning, check at the last minute for any
// directives against the warnings "lint". If, for example, there's an
// `allow(warnings)` in scope then we want to respect that instead.
if level == Level::Warn {
//
// We exempt `FORBIDDEN_LINT_GROUPS` from this because it specifically
// triggers in cases (like #80988) where you have `forbid(warnings)`,
// and so if we turned that into an error, it'd defeat the purpose of the
// future compatibility warning.
if level == Level::Warn && LintId::of(lint) != LintId::of(FORBIDDEN_LINT_GROUPS) {
let (warnings_level, warnings_src) =
self.get_lint_id_level(LintId::of(builtin::WARNINGS), idx, aux);
if let Some(configured_warning_level) = warnings_level {