diff options
Diffstat (limited to 'compiler/rustc_span/src/lib.rs')
| -rw-r--r-- | compiler/rustc_span/src/lib.rs | 82 |
1 files changed, 46 insertions, 36 deletions
diff --git a/compiler/rustc_span/src/lib.rs b/compiler/rustc_span/src/lib.rs index dbc67da37b5..3f72ccd9f89 100644 --- a/compiler/rustc_span/src/lib.rs +++ b/compiler/rustc_span/src/lib.rs @@ -716,12 +716,17 @@ impl Span { (!ctxt.is_root()).then(|| ctxt.outer_expn_data().call_site) } - /// Walk down the expansion ancestors to find a span that's contained within `outer`. + /// Find the first ancestor span that's contained within `outer`. /// - /// The span returned by this method may have a different [`SyntaxContext`] as `outer`. + /// This method traverses the macro expansion ancestors until it finds the first span + /// that's contained within `outer`. + /// + /// The span returned by this method may have a different [`SyntaxContext`] than `outer`. /// If you need to extend the span, use [`find_ancestor_inside_same_ctxt`] instead, /// because joining spans with different syntax contexts can create unexpected results. /// + /// This is used to find the span of the macro call when a parent expr span, i.e. `outer`, is known. + /// /// [`find_ancestor_inside_same_ctxt`]: Self::find_ancestor_inside_same_ctxt pub fn find_ancestor_inside(mut self, outer: Span) -> Option<Span> { while !outer.contains(self) { @@ -730,8 +735,10 @@ impl Span { Some(self) } - /// Walk down the expansion ancestors to find a span with the same [`SyntaxContext`] as - /// `other`. + /// Find the first ancestor span with the same [`SyntaxContext`] as `other`. + /// + /// This method traverses the macro expansion ancestors until it finds a span + /// that has the same [`SyntaxContext`] as `other`. /// /// Like [`find_ancestor_inside_same_ctxt`], but specifically for when spans might not /// overlap. Take care when using this, and prefer [`find_ancestor_inside`] or @@ -747,9 +754,12 @@ impl Span { Some(self) } - /// Walk down the expansion ancestors to find a span that's contained within `outer` and + /// Find the first ancestor span that's contained within `outer` and /// has the same [`SyntaxContext`] as `outer`. /// + /// This method traverses the macro expansion ancestors until it finds a span + /// that is both contained within `outer` and has the same [`SyntaxContext`] as `outer`. + /// /// This method is the combination of [`find_ancestor_inside`] and /// [`find_ancestor_in_same_ctxt`] and should be preferred when extending the returned span. /// If you do not need to modify the span, use [`find_ancestor_inside`] instead. @@ -763,43 +773,43 @@ impl Span { Some(self) } - /// Recursively walk down the expansion ancestors to find the oldest ancestor span with the same - /// [`SyntaxContext`] the initial span. + /// Find the first ancestor span that does not come from an external macro. /// - /// This method is suitable for peeling through *local* macro expansions to find the "innermost" - /// span that is still local and shares the same [`SyntaxContext`]. For example, given + /// This method traverses the macro expansion ancestors until it finds a span + /// that is either from user-written code or from a local macro (defined in the current crate). /// - /// ```ignore (illustrative example, contains type error) - /// macro_rules! outer { - /// ($x: expr) => { - /// inner!($x) - /// } - /// } + /// External macros are those defined in dependencies or the standard library. + /// This method is useful for reporting errors in user-controllable code and avoiding + /// diagnostics inside external macros. /// - /// macro_rules! inner { - /// ($x: expr) => { - /// format!("error: {}", $x) - /// //~^ ERROR mismatched types - /// } - /// } + /// # See also /// - /// fn bar(x: &str) -> Result<(), Box<dyn std::error::Error>> { - /// Err(outer!(x)) - /// } - /// ``` + /// - [`Self::find_ancestor_not_from_macro`] + /// - [`Self::in_external_macro`] + pub fn find_ancestor_not_from_extern_macro(mut self, sm: &SourceMap) -> Option<Span> { + while self.in_external_macro(sm) { + self = self.parent_callsite()?; + } + Some(self) + } + + /// Find the first ancestor span that does not come from any macro expansion. /// - /// if provided the initial span of `outer!(x)` inside `bar`, this method will recurse - /// the parent callsites until we reach `format!("error: {}", $x)`, at which point it is the - /// oldest ancestor span that is both still local and shares the same [`SyntaxContext`] as the - /// initial span. - pub fn find_oldest_ancestor_in_same_ctxt(self) -> Span { - let mut cur = self; - while cur.eq_ctxt(self) - && let Some(parent_callsite) = cur.parent_callsite() - { - cur = parent_callsite; + /// This method traverses the macro expansion ancestors until it finds a span + /// that originates from user-written code rather than any macro-generated code. + /// + /// This method is useful for reporting errors at the exact location users wrote code + /// and providing suggestions at directly editable locations. + /// + /// # See also + /// + /// - [`Self::find_ancestor_not_from_extern_macro`] + /// - [`Span::from_expansion`] + pub fn find_ancestor_not_from_macro(mut self) -> Option<Span> { + while self.from_expansion() { + self = self.parent_callsite()?; } - cur + Some(self) } /// Edition of the crate from which this span came. |