Validate #[stable(feature = "…")] identifier

Author: dtolnay

compiler/rustc_attr/src/builtin.rs

@@ -3,6 +3,7 @@
 use rustc_ast::{self as ast, attr};
 use rustc_ast::{Attribute, LitKind, MetaItem, MetaItemKind, MetaItemLit, NestedMetaItem, NodeId};
 use rustc_ast_pretty::pprust;
+use rustc_errors::ErrorGuaranteed;
 use rustc_feature::{find_gated_cfg, is_builtin_attr_name, Features, GatedCfg};
 use rustc_macros::HashStable_Generic;
 use rustc_session::config::ExpectedValues;
@@ -48,33 +49,27 @@ pub(crate) enum UnsupportedLiteralReason {
     DeprecatedKvPair,
 }
 
-fn handle_errors(sess: &ParseSess, span: Span, error: AttrError) {
+fn handle_errors(sess: &ParseSess, span: Span, error: AttrError) -> ErrorGuaranteed {
     match error {
         AttrError::MultipleItem(item) => {
-            sess.emit_err(session_diagnostics::MultipleItem { span, item });
+            sess.emit_err(session_diagnostics::MultipleItem { span, item })
         }
         AttrError::UnknownMetaItem(item, expected) => {
-            sess.emit_err(session_diagnostics::UnknownMetaItem { span, item, expected });
-        }
-        AttrError::MissingSince => {
-            sess.emit_err(session_diagnostics::MissingSince { span });
-        }
-        AttrError::NonIdentFeature => {
-            sess.emit_err(session_diagnostics::NonIdentFeature { span });
-        }
-        AttrError::MissingFeature => {
-            sess.emit_err(session_diagnostics::MissingFeature { span });
+            sess.emit_err(session_diagnostics::UnknownMetaItem { span, item, expected })
         }
+        AttrError::MissingSince => sess.emit_err(session_diagnostics::MissingSince { span }),
+        AttrError::NonIdentFeature => sess.emit_err(session_diagnostics::NonIdentFeature { span }),
+        AttrError::MissingFeature => sess.emit_err(session_diagnostics::MissingFeature { span }),
         AttrError::MultipleStabilityLevels => {
-            sess.emit_err(session_diagnostics::MultipleStabilityLevels { span });
+            sess.emit_err(session_diagnostics::MultipleStabilityLevels { span })
         }
         AttrError::UnsupportedLiteral(reason, is_bytestr) => {
             sess.emit_err(session_diagnostics::UnsupportedLiteral {
                 span,
                 reason,
                 is_bytestr,
                 start_point_span: sess.source_map().start_point(span),
-            });
+            })
         }
     }
 }
@@ -411,19 +406,23 @@ fn parse_stability(sess: &Session, attr: &Attribute) -> Option<(Symbol, Stabilit
         since = Some(rust_version_symbol());
     }
 
+    let feature = match feature {
+        Some(feature) if rustc_lexer::is_ident(feature.as_str()) => Ok(feature),
+        Some(_bad_feature) => {
+            Err(handle_errors(&sess.parse_sess, attr.span, AttrError::NonIdentFeature))
+        }
+        None => Err(handle_errors(&sess.parse_sess, attr.span, AttrError::MissingFeature)),
+    };
+
+    let since =
+        since.ok_or_else(|| handle_errors(&sess.parse_sess, attr.span, AttrError::MissingSince));
+
     match (feature, since) {
-        (Some(feature), Some(since)) => {
+        (Ok(feature), Ok(since)) => {
             let level = StabilityLevel::Stable { since, allowed_through_unstable_modules: false };
             Some((feature, level))
         }
-        (None, _) => {
-            handle_errors(&sess.parse_sess, attr.span, AttrError::MissingFeature);
-            None
-        }
-        _ => {
-            handle_errors(&sess.parse_sess, attr.span, AttrError::MissingSince);
-            None
-        }
+        (Err(ErrorGuaranteed { .. }), _) | (_, Err(ErrorGuaranteed { .. })) => None,
     }
 }
 
@@ -497,12 +496,19 @@ fn parse_unstability(sess: &Session, attr: &Attribute) -> Option<(Symbol, Stabil
         }
     }
 
-    match (feature, reason, issue) {
-        (Some(feature), reason, Some(_)) => {
-            if !rustc_lexer::is_ident(feature.as_str()) {
-                handle_errors(&sess.parse_sess, attr.span, AttrError::NonIdentFeature);
-                return None;
-            }
+    let feature = match feature {
+        Some(feature) if rustc_lexer::is_ident(feature.as_str()) => Ok(feature),
+        Some(_bad_feature) => {
+            Err(handle_errors(&sess.parse_sess, attr.span, AttrError::NonIdentFeature))
+        }
+        None => Err(handle_errors(&sess.parse_sess, attr.span, AttrError::MissingFeature)),
+    };
+
+    let issue =
+        issue.ok_or_else(|| sess.emit_err(session_diagnostics::MissingIssue { span: attr.span }));
+
+    match (feature, issue) {
+        (Ok(feature), Ok(_)) => {
             let level = StabilityLevel::Unstable {
                 reason: UnstableReason::from_opt_reason(reason),
                 issue: issue_num,
@@ -511,14 +517,7 @@ fn parse_unstability(sess: &Session, attr: &Attribute) -> Option<(Symbol, Stabil
             };
             Some((feature, level))
         }
-        (None, _, _) => {
-            handle_errors(&sess.parse_sess, attr.span, AttrError::MissingFeature);
-            return None;
-        }
-        _ => {
-            sess.emit_err(session_diagnostics::MissingIssue { span: attr.span });
-            return None;
-        }
+        (Err(ErrorGuaranteed { .. }), _) | (_, Err(ErrorGuaranteed { .. })) => None,
     }
 }