fix canonicalize on windows

Cargo.toml

@@ -12,6 +12,7 @@ documentation = "https://rustwasm.github.io/wasm-pack/"
 [dependencies]
 atty = "0.2.11"
 cargo_metadata = "0.6.0"
+cfg-if = "0.1.5"
 console = "0.6.1"
 curl = "0.4.13"
 failure = "0.1.2"

src/command/build.rs

@@ -2,6 +2,7 @@
 
 use bindgen;
 use build;
+use command::utils::canonicalize_path;
 use command::utils::{create_pkg_dir, set_crate_path};
 use emoji;
 use error::Error;
@@ -141,7 +142,7 @@ impl Build {
         PBAR.message(&format!(
             "{} Your wasm pkg is ready to publish at {:#?}.",
             emoji::PACKAGE,
-            self.out_dir.canonicalize().unwrap_or(self.out_dir.clone())
+            canonicalize_path(self.out_dir.clone()).unwrap_or(self.out_dir.clone())
         ));
         Ok(())
     }

src/command/utils.rs

@@ -4,19 +4,17 @@ use emoji;
 use error::Error;
 use progressbar::Step;
 use std::fs;
-use std::io;
 use std::path::{Path, PathBuf};
 use PBAR;
 
 /// If an explicit path is given, then use it, otherwise assume the current
 /// directory is the crate path.
-pub fn set_crate_path(path: Option<PathBuf>) -> io::Result<PathBuf> {
+pub fn set_crate_path(path: Option<PathBuf>) -> Result<PathBuf, Error> {
     let crate_path = match path {
         Some(p) => p,
         None => PathBuf::from("."),
     };
-
-    crate_path.canonicalize()
+    canonicalize_path(crate_path)
 }
 
 /// Construct our `pkg` directory in the crate.
@@ -44,3 +42,29 @@ pub fn find_pkg_directory(path: &Path) -> Option<PathBuf> {
 fn is_pkg_directory(path: &Path) -> bool {
     path.exists() && path.is_dir() && path.ends_with("pkg")
 }
+
+cfg_if! {
+    if #[cfg(windows)] {
+        /// Strips UNC from canonical path on Windows.
+        /// See https://github.com/rust-lang/rust/issues/42869 for why this is needed.
+        pub fn canonicalize_path(path: PathBuf) -> Result<PathBuf, Error> {
+            use std::ffi::OsString;
+            use std::os::windows::prelude::*;
+            let canonical = path.canonicalize()?;
+            let vec_chars = canonical.as_os_str().encode_wide().collect::<Vec<u16>>();
+            if vec_chars[0..4] == [92, 92, 63, 92] {
+                Ok(Path::new(&OsString::from_wide(&vec_chars[4..])).to_owned())
+            }
+            else {
+                Ok(canonical)
+            }
+        }
+    }
+    else {
+        /// Strips UNC from canonical path on Windows.
+        pub fn canonicalize_path(path: PathBuf) -> Result<PathBuf, Error> {
+            let canonical = path.canonicalize()?;
+            Ok(canonical)
+        }
+    }
+}

src/lib.rs

@@ -3,6 +3,8 @@
 #![deny(missing_docs)]
 
 extern crate cargo_metadata;
+#[macro_use]
+extern crate cfg_if;
 extern crate console;
 extern crate curl;
 #[macro_use]