moved crates in lib/ to src/, renamed crates, modified some files' text (#660)

moved crates in lib/ to src/, renamed crates, modified some files' text (#660)

cranelift/reader/src/error.rs

@@ -0,0 +1,52 @@
+//! Define the `Location`, `ParseError`, and `ParseResult` types.
+
+#![macro_use]
+
+use std::fmt;
+
+/// The location of a `Token` or `Error`.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
+pub struct Location {
+    /// Line number. Command-line arguments are line 0 and source file
+    /// lines start from 1.
+    pub line_number: usize,
+}
+
+/// A parse error is returned when the parse failed.
+#[derive(Debug)]
+pub struct ParseError {
+    /// Location of the error.
+    pub location: Location,
+    /// Error message.
+    pub message: String,
+}
+
+impl fmt::Display for ParseError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        if self.location.line_number == 0 {
+            write!(f, "command-line arguments: {}", self.message)
+        } else {
+            write!(f, "{}: {}", self.location.line_number, self.message)
+        }
+    }
+}
+
+/// Result of a parser operation. The `ParseError` variant includes a location.
+pub type ParseResult<T> = Result<T, ParseError>;
+
+// Create an `Err` variant of `ParseResult<X>` from a location and `format!` args.
+macro_rules! err {
+    ( $loc:expr, $msg:expr ) => {
+        Err($crate::ParseError {
+            location: $loc.clone(),
+            message: $msg.to_string(),
+        })
+    };
+
+    ( $loc:expr, $fmt:expr, $( $arg:expr ),+ ) => {
+        Err($crate::ParseError {
+            location: $loc.clone(),
+            message: format!( $fmt, $( $arg ),+ ),
+        })
+    };
+}