Improving error messages

cedar-policy-core/src/error_macros.rs

@@ -32,6 +32,29 @@ macro_rules! impl_diagnostic_from_source_loc_field {
     };
 }
 
+/// Macro which implements the `.labels()` and `.source_code()` methods of
+/// `miette::Diagnostic` by using the parameters `$i` and `$j` which must be the name
+/// of fields of type `Loc`.
+/// Both spans are underlined, only the first span is reported as the source code location
+#[macro_export]
+macro_rules! impl_diagnostic_from_source_loc_fields {
+    ( $i:ident , $j:ident ) => {
+        fn source_code(&self) -> Option<&dyn miette::SourceCode> {
+            Some(&self.$i.src as &dyn miette::SourceCode)
+        }
+
+        fn labels(&self) -> Option<Box<dyn Iterator<Item = miette::LabeledSpan> + '_>> {
+            Some(Box::new(
+                [
+                    miette::LabeledSpan::underline(self.$i.span),
+                    miette::LabeledSpan::underline(self.$j.span),
+                ]
+                .into_iter(),
+            ) as _)
+        }
+    };
+}
+
 /// Macro which implements the `.labels()` and `.source_code()` methods of
 /// `miette::Diagnostic` by using the parameter `$i` which must be the name
 /// of a field of type `Option<Loc>`
@@ -52,6 +75,42 @@ macro_rules! impl_diagnostic_from_source_loc_opt_field {
     };
 }
 
+/// Macro which implements the `.labels()` and `.source_code()` methods of
+/// `miette::Diagnostic` by using the parameters `$i` and `$j` which must be the name
+/// of fields of type `Option<Loc>`
+#[macro_export]
+macro_rules! impl_diagnostic_from_source_loc_opt_fields {
+    ( $i:ident , $j:ident ) => {
+        fn source_code(&self) -> Option<&dyn miette::SourceCode> {
+            self.$i
+                .as_ref()
+                .map(|loc| &loc.src as &dyn miette::SourceCode)
+                .or_else(|| {
+                    self.$j
+                        .as_ref()
+                        .map(|loc| &loc.src as &dyn miette::SourceCode)
+                })
+        }
+
+        fn labels(&self) -> Option<Box<dyn Iterator<Item = miette::LabeledSpan> + '_>> {
+            let x = self
+                .$i
+                .as_ref()
+                .map(|loc| miette::LabeledSpan::underline(loc.span));
+            let y = self
+                .$j
+                .as_ref()
+                .map(|loc| miette::LabeledSpan::underline(loc.span));
+
+            match (x, y) {
+                (None, None) => None,
+                (Some(span), None) | (None, Some(span)) => Some(Box::new(std::iter::once(span))),
+                (Some(span_a), Some(span_b)) => Some(Box::new([span_a, span_b].into_iter()) as _),
+            }
+        }
+    };
+}
+
 /// Macro which implements the `.labels()` and `.source_code()` methods of
 /// `miette::Diagnostic` by using the parameter `$i` which must be an `Expr`
 /// (or `Box<Expr>`) type field.

cedar-policy-validator/src/cedar_schema/ast.rs

@@ -262,7 +262,7 @@ pub struct AttrDecl {
 }
 
 /// The target of a [`PRAppDecl`]
-#[derive(Debug, Clone, PartialEq, Eq)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum PR {
     /// Applies to the `principal` variable
     Principal,