Turn unresolved references and citations into warnings

crates/typst/src/model/cite.rs

@@ -1,3 +1,5 @@
+use ecow::eco_format;
+
 use crate::diag::{error, At, HintedString, SourceResult};
 use crate::engine::Engine;
 use crate::foundations::{
@@ -5,7 +7,7 @@ use crate::foundations::{
 };
 use crate::introspection::Locatable;
 use crate::model::bibliography::Works;
-use crate::model::CslStyle;
+use crate::model::{unresolved_reference, BibliographyElem, CslStyle};
 use crate::text::{Lang, Region, TextElem};
 
 /// Cite a work from the bibliography.
@@ -40,7 +42,7 @@ use crate::text::{Lang, Region, TextElem};
 /// This function indirectly has dedicated syntax. [References]($ref) can be
 /// used to cite works from the bibliography. The label then corresponds to the
 /// citation key.
-#[elem(Synthesize)]
+#[elem(Synthesize, Show)]
 pub struct CiteElem {
     /// The citation key that identifies the entry in the bibliography that
     /// shall be cited, as a label.
@@ -117,6 +119,26 @@ impl Synthesize for Packed<CiteElem> {
     }
 }
 
+impl Show for Packed<CiteElem> {
+    #[typst_macros::time(name = "cite", span = self.span())]
+    fn show(&self, engine: &mut Engine, _: StyleChain) -> SourceResult<Content> {
+        if !BibliographyElem::has(engine, self.key) {
+            return Ok(unresolved_reference(
+                engine,
+                eco_format!(
+                    "key `{}` does not exist in the bibliography",
+                    self.key.as_str()
+                ),
+                "cite",
+                self.key,
+                self.span(),
+            ));
+        }
+
+        Ok(self.clone().pack())
+    }
+}
+
 cast! {
     CiteElem,
     v: Content => v.unpack::<Self>().map_err(|_| "expected citation")?,

crates/typst/src/model/reference.rs

@@ -1,18 +1,20 @@
 use comemo::Track;
-use ecow::eco_format;
+use ecow::{eco_format, EcoString};
 
-use crate::diag::{bail, At, Hint, SourceResult};
+use crate::diag::{bail, At, Hint, SourceDiagnostic, SourceResult};
 use crate::engine::Engine;
 use crate::foundations::{
-    cast, elem, Content, Context, Func, IntoValue, Label, NativeElement, Packed, Show,
-    Smart, StyleChain, Synthesize,
+    cast, elem, Content, Context, Func, IntoValue, Label, NativeElement, Packed, Repr,
+    Show, Smart, StyleChain, Synthesize,
 };
-use crate::introspection::{Counter, Locatable};
+use crate::introspection::{Counter, Locatable, QueryError};
 use crate::math::EquationElem;
 use crate::model::{
     BibliographyElem, CiteElem, Destination, Figurable, FootnoteElem, Numbering,
 };
-use crate::text::TextElem;
+use crate::syntax::{is_valid_label_literal, Span};
+use crate::text::{RawContent, RawElem, TextElem};
+use crate::visualize::Color;
 
 /// A reference to a label or bibliography.
 ///
@@ -163,22 +165,25 @@ impl Synthesize for Packed<RefElem> {
 impl Show for Packed<RefElem> {
     #[typst_macros::time(name = "ref", span = self.span())]
     fn show(&self, engine: &mut Engine, styles: StyleChain) -> SourceResult<Content> {
-        let target = *self.target();
-        let elem = engine.introspector.query_label(target);
         let span = self.span();
+        let result = engine.introspector.query_label(self.target);
 
-        if BibliographyElem::has(engine, target) {
-            if elem.is_ok() {
+        if BibliographyElem::has(engine, self.target) {
+            if result.is_ok() {
                 bail!(span, "label occurs in the document and its bibliography");
             }
 
             return Ok(to_citation(self, engine, styles)?.pack().spanned(span));
         }
 
-        let elem = elem.at(span)?;
+        if let Err(error @ QueryError::MissingLabel(_)) = result {
+            return Ok(unresolved_reference(engine, error, "ref", self.target, span));
+        }
+
+        let elem = result.at(span)?;
 
         if let Some(footnote) = elem.to_packed::<FootnoteElem>() {
-            return Ok(footnote.into_ref(target).pack().spanned(span));
+            return Ok(footnote.into_ref(self.target).pack().spanned(span));
         }
 
         let elem = elem.clone();
@@ -305,3 +310,26 @@ pub trait Refable {
     /// Returns the numbering of this element.
     fn numbering(&self) -> Option<&Numbering>;
 }
+
+/// Generates a warning for an unresolved reference and returns placeholder
+/// content.
+pub(crate) fn unresolved_reference(
+    engine: &mut Engine,
+    message: impl Into<EcoString>,
+    func: &str,
+    target: Label,
+    span: Span,
+) -> Content {
+    engine.sink.warn(SourceDiagnostic::warning(span, message));
+
+    let text = if is_valid_label_literal(target.as_str()) {
+        eco_format!("@{}", target.as_str())
+    } else {
+        eco_format!("#{func}(label({}))", target.as_str().repr())
+    };
+
+    return RawElem::new(RawContent::Text(text))
+        .pack()
+        .spanned(span)
+        .styled(TextElem::set_fill(Color::RED.into()));
+}

tests/suite/foundations/label.typ

@@ -72,16 +72,16 @@ _Visible_
 // Hint: 1-8 only the last label is used, the rest are ignored
 = Hello <a> <b>
 
-// Warning: 12-19 content labelled multiple times
-// Hint: 12-19 only the last label is used, the rest are ignored
-#let f = [#block()<c>]
+// Warning: 12-26 content labelled multiple times
+// Hint: 12-26 only the last label is used, the rest are ignored
+#let f = [#metadata(none)<c>]
 #f<d>
 
-// Warning: 6-13 content labelled multiple times
-// Hint: 6-13 only the last label is used, the rest are ignored
-#[#[#block()]<e>]<f>
+// Warning: 6-20 content labelled multiple times
+// Hint: 6-20 only the last label is used, the rest are ignored
+#[#[#metadata(none)]<e>]<f>
 
-// Error: 1-3 label `<a>` does not exist in the document
+// Warning: 1-3 label `<a>` does not exist in the document
 @a
 
 --- label-unattached-warn ---

tests/suite/model/cite.typ

@@ -49,6 +49,17 @@ A @netwok @arrgh @quark, B.
 #show bibliography: none
 #bibliography("/assets/bib/works.bib")
 
+--- cite-missing ---
+// Warning: 2-15 key `peter` does not exist in the bibliography
+// Warning: 31-37 label `<extra>` does not exist in the document
+#cite(<peter>) @netwok @arrgh @extra
+
+// Warning: 2-20 key `>?&` does not exist in the bibliography
+#cite(label(">?&"))
+
+#show bibliography: none
+#bibliography("/assets/bib/works.bib")
+
 --- issue-785-cite-locate ---
 // Test citation in other introspection.
 #set page(width: 180pt)

tests/suite/model/ref.typ

@@ -10,9 +10,15 @@ See @setup.
 As seen in @intro, we proceed.
 
 --- ref-label-missing ---
-// Error: 1-5 label `<foo>` does not exist in the document
+// Warning: 1-5 label `<foo>` does not exist in the document
 @foo
 
+--- ref-label-complex-missing ---
+#set page(width: auto)
+
+// Warning: 2-28 label `label("is;/"bad%//#")` does not exist in the document
+#ref(label("is;\"bad%//#"))
+
 --- ref-label-duplicate ---
 = First <foo>
 = Second <foo>