Merge pull request #694 from pest-parser/CAD97-patch-1

Remove trait bound from Error type

pest/src/error.rs

@@ -16,6 +16,7 @@ use alloc::string::String;
 use alloc::string::ToString;
 use alloc::vec::Vec;
 use core::cmp;
+use core::fmt;
 use core::mem;
 
 use crate::position::Position;
@@ -25,8 +26,7 @@ use crate::RuleType;
 /// Parse-related error type.
 #[derive(Clone, Debug, Eq, Hash, PartialEq)]
 #[cfg_attr(feature = "std", derive(thiserror::Error))]
-#[cfg_attr(feature = "std", error("{}", self.format()))]
-pub struct Error<R: RuleType> {
+pub struct Error<R> {
     /// Variant of the error
     pub variant: ErrorVariant<R>,
     /// Location within the input string
@@ -41,17 +41,15 @@ pub struct Error<R: RuleType> {
 /// Different kinds of parsing errors.
 #[derive(Clone, Debug, Eq, Hash, PartialEq)]
 #[cfg_attr(feature = "std", derive(thiserror::Error))]
-pub enum ErrorVariant<R: RuleType> {
+pub enum ErrorVariant<R> {
     /// Generated parsing error with expected and unexpected `Rule`s
-    #[cfg_attr(feature = "std", error("parsing error: {}", self.message()))]
     ParsingError {
         /// Positive attempts
         positives: Vec<R>,
         /// Negative attempts
         negatives: Vec<R>,
     },
     /// Custom error with a message
-    #[cfg_attr(feature = "std", error("{}", self.message()))]
     CustomError {
         /// Short explanation
         message: String,
@@ -520,6 +518,21 @@ impl<R: RuleType> ErrorVariant<R> {
     }
 }
 
+impl<R: RuleType> fmt::Display for Error<R> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}", self.format())
+    }
+}
+
+impl<R: RuleType> fmt::Display for ErrorVariant<R> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            ErrorVariant::ParsingError { .. } => write!(f, "parsing error: {}", self.message()),
+            ErrorVariant::CustomError { .. } => write!(f, "{}", self.message()),
+        }
+    }
+}
+
 fn visualize_whitespace(input: &str) -> String {
     input.to_owned().replace('\r', "␍").replace('\n', "␊")
 }