1 files changed, 67 insertions, 0 deletions
diff --git a/crates/cargo-platform/src/error.rs b/crates/cargo-platform/src/error.rs
new file mode 100644
index 0000000..bf4b35f
--- /dev/null
+++ b/crates/cargo-platform/src/error.rs
@@ -0,0 +1,67 @@
+use std::fmt;
+
+#[derive(Debug)]
+pub struct ParseError {
+    kind: ParseErrorKind,
+    orig: String,
+}
+
+#[non_exhaustive]
+#[derive(Debug)]
+pub enum ParseErrorKind {
+    UnterminatedString,
+    UnexpectedChar(char),
+    UnexpectedToken {
+        expected: &'static str,
+        found: &'static str,
+    },
+    IncompleteExpr(&'static str),
+    UnterminatedExpression(String),
+    InvalidTarget(String),
+}
+
+impl fmt::Display for ParseError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(
+            f,
+            "failed to parse `{}` as a cfg expression: {}",
+            self.orig, self.kind
+        )
+    }
+}
+
+impl fmt::Display for ParseErrorKind {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        use ParseErrorKind::*;
+        match self {
+            UnterminatedString => write!(f, "unterminated string in cfg"),
+            UnexpectedChar(ch) => write!(
+                f,
+                "unexpected character `{}` in cfg, expected parens, a comma, \
+                 an identifier, or a string",
+                ch
+            ),
+            UnexpectedToken { expected, found } => {
+                write!(f, "expected {}, found {}", expected, found)
+            }
+            IncompleteExpr(expected) => {
+                write!(f, "expected {}, but cfg expression ended", expected)
+            }
+            UnterminatedExpression(s) => {
+                write!(f, "unexpected content `{}` found after cfg expression", s)
+            }
+            InvalidTarget(s) => write!(f, "invalid target specifier: {}", s),
+        }
+    }
+}
+
+impl std::error::Error for ParseError {}
+
+impl ParseError {
+    pub fn new(orig: &str, kind: ParseErrorKind) -> ParseError {
+        ParseError {
+            kind,
+            orig: orig.to_string(),
+        }
+    }
+}