Display magic number mismatch in error (#1307)

rylev · web-flow · commit 76f67e58dd0c · 2023-11-27T09:11:49.000-06:00
Signed-off-by: Ryan Levick &lt;ryan.levick@fermyon.com&gt;
diff --git a/crates/wasmparser/src/binary_reader.rs b/crates/wasmparser/src/binary_reader.rs
@@ -1518,7 +1518,7 @@ impl<'a> BinaryReader<'a> {
         let magic_number = self.read_bytes(4)?;
         if magic_number != WASM_MAGIC_NUMBER {
             return Err(BinaryReaderError::new(
-                "magic header not detected: bad magic number",
+                format!("magic header not detected: bad magic number - expected={WASM_MAGIC_NUMBER:#x?} actual={magic_number:#x?}"),
                 self.original_position() - 4,
             ));
         }

Original file line number	Diff line number	Diff line change
`@@ -1518,7 +1518,7 @@ impl<'a> BinaryReader<'a> {`
`1518`	`1518`	`let magic_number = self.read_bytes(4)?;`
`1519`	`1519`	`if magic_number != WASM_MAGIC_NUMBER {`
`1520`	`1520`	`return Err(BinaryReaderError::new(`
`1521`		`- "magic header not detected: bad magic number",`
	`1521`	`+ format!("magic header not detected: bad magic number - expected={WASM_MAGIC_NUMBER:#x?} actual={magic_number:#x?}"),`
`1522`	`1522`	`self.original_position() - 4,`
`1523`	`1523`	`));`
`1524`	`1524`	`}`