Auto merge of #6803 - ehuss:doc-open-multi, r=alexcrichton

Allow `cargo doc --open` with multiple packages.

If `cargo doc --open` builds multiple packages, open the first one. This seems pretty natural to me (the first one on the command line, or the first default member if `default-members` is specified, or the root of a workspace). Rustdoc shows a list of crates in the sidebar, so if it doesn't open the one the user wants, it's a trivial matter of clicking on the crate name.

@alexcrichton specifically asked for an error [here](#1828 (diff)). However, at the time I don't think rustdoc dynamically generated the "Crates" listing in the sidebar. Alex, I wonder if your stance still holds?

Closes #5145

src/cargo/ops/cargo_doc.rs

@@ -39,6 +39,7 @@ pub fn doc(ws: &Workspace<'_>, options: &DocOptions<'_>) -> CargoResult<()> {
 
     let mut lib_names = HashMap::new();
     let mut bin_names = HashMap::new();
+    let mut names = Vec::new();
     for package in &pkgs {
         for target in package.targets().iter().filter(|t| t.documented()) {
             if target.is_lib() {
@@ -62,27 +63,16 @@ pub fn doc(ws: &Workspace<'_>, options: &DocOptions<'_>) -> CargoResult<()> {
                     package
                 );
             }
+            names.push(target.crate_name());
         }
     }
 
     ops::compile(ws, &options.compile_opts)?;
 
     if options.open_result {
-        let name = if pkgs.len() > 1 {
-            failure::bail!(
-                "Passing multiple packages and `open` is not supported.\n\
-                 Please re-run this command with `-p <spec>` where `<spec>` \
-                 is one of the following:\n  {}",
-                pkgs.iter()
-                    .map(|p| p.name().as_str())
-                    .collect::<Vec<_>>()
-                    .join("\n  ")
-            );
-        } else {
-            match lib_names.keys().chain(bin_names.keys()).nth(0) {
-                Some(s) => s.to_string(),
-                None => return Ok(()),
-            }
+        let name = match names.first() {
+            Some(s) => s.to_string(),
+            None => return Ok(()),
         };
 
         // Don't bother locking here as if this is getting deleted there's

tests/testsuite/doc.rs

@@ -1012,6 +1012,7 @@ fn doc_all_member_dependency_same_name() {
 }
 
 #[test]
+#[cfg(not(any(target_os = "windows", target_os = "macos")))]
 fn doc_workspace_open_help_message() {
     let p = project()
         .file(
@@ -1029,19 +1030,10 @@ fn doc_workspace_open_help_message() {
 
     // The order in which bar is compiled or documented is not deterministic
     p.cargo("doc --all --open")
-        .with_status(101)
+        .env("BROWSER", "echo")
         .with_stderr_contains("[..] Documenting bar v0.1.0 ([..])")
         .with_stderr_contains("[..] Documenting foo v0.1.0 ([..])")
-        .with_stderr_contains(
-            "error: Passing multiple packages and `open` \
-             is not supported.",
-        )
-        .with_stderr_contains(
-            "Please re-run this command with `-p <spec>` \
-             where `<spec>` is one of the following:",
-        )
-        .with_stderr_contains("  foo")
-        .with_stderr_contains("  bar")
+        .with_stderr_contains("[..] Opening [..]/foo/index.html")
         .run();
 }