core: clearly define when module lookup is path-based vs URL-based

The rules are now as follows:

* In `import` statements, as mandated by the WHATWG specification,
  the import specifier is always treated as a URL.
  If it is a relative URL, it must start with either / or ./ or ../

* A script name passed to deno as a command line argument may be either
  an absolute URL or a local path.
  - If the name starts with a valid URI scheme followed by a colon, e.g.
    'http:', 'https:', 'file:', 'foo+bar:', it always interpreted as a
    URL (even if Deno doesn't support the indicated protocol).
  - Otherwise, the script name is interpreted as a local path. The local
    path may be relative, and operating system semantics determine how
    it is resolved. Prefixing a relative path with ./ is not required.

cli/compiler.rs

@@ -249,7 +249,7 @@ mod tests {
     tokio_util::init(|| {
       let specifier = "./tests/002_hello.ts";
       use deno::ModuleSpecifier;
-      let module_name = ModuleSpecifier::resolve_root(specifier)
+      let module_name = ModuleSpecifier::resolve_url_or_path(specifier)
         .unwrap()
         .to_string();
 
@@ -296,7 +296,7 @@ mod tests {
   fn test_bundle_async() {
     let specifier = "./tests/002_hello.ts";
     use deno::ModuleSpecifier;
-    let module_name = ModuleSpecifier::resolve_root(specifier)
+    let module_name = ModuleSpecifier::resolve_url_or_path(specifier)
       .unwrap()
       .to_string();
 

cli/deno_error.rs

@@ -110,7 +110,8 @@ impl DenoError {
         use ModuleResolutionError::*;
         match err {
           InvalidUrl(err) | InvalidBaseUrl(err) => Self::url_error_kind(err),
-          ImportPathPrefixMissing => ErrorKind::ImportPathPrefixMissing,
+          InvalidPath => ErrorKind::InvalidPath,
+          ImportPrefixMissing => ErrorKind::ImportPrefixMissing,
         }
       }
       Repr::Diagnostic(ref _err) => ErrorKind::Diagnostic,

cli/flags.rs

@@ -630,7 +630,9 @@ pub enum DenoSubcommand {
 
 fn get_default_bundle_filename(source_file: &str) -> String {
   use deno::ModuleSpecifier;
-  let url = ModuleSpecifier::resolve_root(source_file).unwrap().to_url();
+  let url = ModuleSpecifier::resolve_url_or_path(source_file)
+    .unwrap()
+    .to_url();
   let path_segments = url.path_segments().unwrap();
   let last = path_segments.last().unwrap();
   String::from(last.trim_end_matches(".ts").trim_end_matches(".js"))

cli/import_map.rs

@@ -178,9 +178,7 @@ impl ImportMap {
         continue;
       }
 
-      let normalized_address = ModuleSpecifier::resolve(&url_string, ".")
-        .expect("Address should be valid module specifier");
-      normalized_addresses.push(normalized_address);
+      normalized_addresses.push(url.into());
     }
 
     normalized_addresses

cli/msg.fbs

@@ -102,6 +102,7 @@ enum ErrorKind: byte {
   WouldBlock,
   InvalidInput,
   InvalidData,
+  InvalidPath,
   TimedOut,
   Interrupted,
   WriteZero,
@@ -141,7 +142,7 @@ enum ErrorKind: byte {
   NoAsyncSupport,
   NoSyncSupport,
   ImportMapError,
-  ImportPathPrefixMissing,
+  ImportPrefixMissing,
 
   // other kinds
   Diagnostic,

cli/ops.rs

@@ -2053,7 +2053,7 @@ fn op_create_worker(
   err_check(worker.execute("denoMain()"));
   err_check(worker.execute("workerMain()"));
 
-  let module_specifier = ModuleSpecifier::resolve_root(specifier)?;
+  let module_specifier = ModuleSpecifier::resolve_url_or_path(specifier)?;
 
   let op =
     worker

cli/state.rs

@@ -170,7 +170,8 @@ impl Loader for ThreadSafeState {
       }
     }
 
-    ModuleSpecifier::resolve(specifier, referrer).map_err(DenoError::from)
+    ModuleSpecifier::resolve_import(specifier, referrer)
+      .map_err(DenoError::from)
   }
 
   /// Given an absolute url, load its source code.
@@ -252,7 +253,7 @@ impl ThreadSafeState {
       None
     } else {
       let root_specifier = argv_rest[1].clone();
-      match ModuleSpecifier::resolve_root(&root_specifier) {
+      match ModuleSpecifier::resolve_url_or_path(&root_specifier) {
         Ok(specifier) => Some(specifier),
         Err(e) => {
           // TODO: handle unresolvable specifier

cli/worker.rs

@@ -141,7 +141,7 @@ mod tests {
   #[test]
   fn execute_mod_esm_imports_a() {
     let module_specifier =
-      ModuleSpecifier::resolve_root("tests/esm_imports_a.js").unwrap();
+      ModuleSpecifier::resolve_url_or_path("tests/esm_imports_a.js").unwrap();
     let argv = vec![String::from("./deno"), module_specifier.to_string()];
     let state = ThreadSafeState::new(
       flags::DenoFlags::default(),
@@ -169,7 +169,7 @@ mod tests {
   #[test]
   fn execute_mod_circular() {
     let module_specifier =
-      ModuleSpecifier::resolve_root("tests/circular1.js").unwrap();
+      ModuleSpecifier::resolve_url_or_path("tests/circular1.js").unwrap();
     let argv = vec![String::from("./deno"), module_specifier.to_string()];
     let state = ThreadSafeState::new(
       flags::DenoFlags::default(),
@@ -197,7 +197,7 @@ mod tests {
   #[test]
   fn execute_006_url_imports() {
     let module_specifier =
-      ModuleSpecifier::resolve_root("tests/006_url_imports.ts").unwrap();
+      ModuleSpecifier::resolve_url_or_path("tests/006_url_imports.ts").unwrap();
     let argv = vec![String::from("deno"), module_specifier.to_string()];
     let mut flags = flags::DenoFlags::default();
     flags.reload = true;
@@ -327,7 +327,7 @@ mod tests {
       // "foo" is not a valid module specifier so this should return an error.
       let mut worker = create_test_worker();
       let module_specifier =
-        ModuleSpecifier::resolve_root("does-not-exist").unwrap();
+        ModuleSpecifier::resolve_url_or_path("does-not-exist").unwrap();
       let result = worker.execute_mod_async(&module_specifier, false).wait();
       assert!(result.is_err());
     })
@@ -340,7 +340,7 @@ mod tests {
       // tests).
       let mut worker = create_test_worker();
       let module_specifier =
-        ModuleSpecifier::resolve_root("./tests/002_hello.ts").unwrap();
+        ModuleSpecifier::resolve_url_or_path("./tests/002_hello.ts").unwrap();
       let result = worker.execute_mod_async(&module_specifier, false).wait();
       assert!(result.is_ok());
     })