Improve error messages for unknown variables in evalerror

crates/simplexpr/src/eval.rs

@@ -10,7 +10,7 @@ use std::collections::HashMap;
 #[derive(Debug, thiserror::Error)]
 pub enum EvalError {
     #[error("Tried to reference variable `{0}`, but we cannot access variables here")]
-    NoVariablesAllowed(String),
+    NoVariablesAllowed(VarName),
 
     #[error("Invalid regex: {0}")]
     InvalidRegex(#[from] regex::Error),
@@ -28,7 +28,7 @@ pub enum EvalError {
     UnknownFunction(String),
 
     #[error("Unknown variable {0}")]
-    UnknownVariable(String),
+    UnknownVariable(VarName),
 
     #[error("Unable to index into value {0}")]
     CannotIndex(String),
@@ -116,7 +116,7 @@ impl SimplExpr {
             )),
             VarRef(span, ref name) => match variables.get(name) {
                 Some(value) => Ok(Literal(span, value.clone())),
-                None => Err(EvalError::UnknownVariable(name.to_string()).at(span)),
+                None => Err(EvalError::UnknownVariable(name.clone()).at(span)),
             },
         }
     }

crates/yuck/src/format_diagnostic.rs

@@ -11,6 +11,9 @@ use crate::{
 use super::parser::parse_error;
 use eww_shared_util::{AttrName, Span, Spanned, VarName};
 
+fn span_to_primary_label(span: Span) -> Label<usize> {
+    Label::primary(span.2, span.0..span.1)
+}
 fn span_to_secondary_label(span: Span) -> Label<usize> {
     Label::secondary(span.2, span.0..span.1)
 }
@@ -189,7 +192,15 @@ impl ToDiagnostic for simplexpr::parser::lexer::LexicalError {
 
 impl ToDiagnostic for simplexpr::eval::EvalError {
     fn to_diagnostic(&self) -> Diagnostic<usize> {
-        gen_diagnostic!(self, self.span())
+        use simplexpr::eval::EvalError::*;
+        match self {
+            UnresolvedVariable(name) | UnknownVariable(name) | NoVariablesAllowed(name) => gen_diagnostic! {
+                msg = self,
+                note = format!("If you meant to use the literal value \"{}\", surround the value in quotes", name)
+            },
+            Spanned(span, error) => error.as_ref().to_diagnostic().with_label(span_to_primary_label(*span)),
+            _ => gen_diagnostic!(self, self.span()),
+        }
     }
 }
 

crates/yuck/src/parser/lexer.rs

@@ -92,6 +92,8 @@ impl Lexer {
     }
 }
 
+// TODO string literal interpolation stuff by looking for indexes of {{ and }}?
+
 impl Iterator for Lexer {
     type Item = Result<(usize, Token, usize), parse_error::ParseError>;
 

examples/eww-bar/eww.yuck

@@ -45,11 +45,11 @@
 (defpoll music :interval "5s" "playerctl metadata --format '{{ artist }} - {{ title }}' || true")
 (defpoll volume :interval "16s" "scripts/getvol")
 
-(defpoll number_day :interval "5h" "date '+%d'")
-(defpoll month :interval "10h" "date '+%b'")
-(defpoll min :interval "10s" "date '+%M'")
-(defpoll hour :interval "1m" "date '+%H'")
-(defpoll year_full :interval "15h" "date '+%Y'")
+(defpoll number_day :interval "5h"  "date '+%d'")
+(defpoll month      :interval "10h" "date '+%b'")
+(defpoll min        :interval "10s" "date '+%M'")
+(defpoll hour       :interval "1m"  "date '+%H'")
+(defpoll year_full  :interval "15h" "date '+%Y'")
 
 (deflisten battery-remaining "/sys/class/power_supply/BAT0/capacity")