Auto merge of #9595 - ehuss:ws-doc-collision-back-compat, r=alexcrichton

Relax doc collision error.

#9526 moved the `cargo doc` output name collision code to be shared with the other collision detection code. However, the way it detected collisions wasn't quite the same, and started generating errors for situations that were just warnings before. It was intended that the code should behave the same, so this PR relaxes the checks to be more like the original code.  (It's still not 100% the same, but should be close enough.)

Closes #9564

src/cargo/core/compiler/context/mod.rs

@@ -507,17 +507,35 @@ impl<'a, 'cfg> Context<'a, 'cfg> {
             .collect::<Vec<_>>();
         // Sort for consistent error messages.
         keys.sort_unstable();
+        // These are kept separate to retain compatibility with older
+        // versions, which generated an error when there was a duplicate lib
+        // or bin (but the old code did not check bin<->lib collisions). To
+        // retain backwards compatibility, this only generates an error for
+        // duplicate libs or duplicate bins (but not both). Ideally this
+        // shouldn't be here, but since there isn't a complete workaround,
+        // yet, this retains the old behavior.
+        let mut doc_libs = HashMap::new();
+        let mut doc_bins = HashMap::new();
         for unit in keys {
+            if unit.mode.is_doc() && self.is_primary_package(unit) {
+                // These situations have been an error since before 1.0, so it
+                // is not a warning like the other situations.
+                if unit.target.is_lib() {
+                    if let Some(prev) = doc_libs.insert((unit.target.crate_name(), unit.kind), unit)
+                    {
+                        doc_collision_error(unit, prev)?;
+                    }
+                } else if let Some(prev) =
+                    doc_bins.insert((unit.target.crate_name(), unit.kind), unit)
+                {
+                    doc_collision_error(unit, prev)?;
+                }
+            }
             for output in self.outputs(unit)?.iter() {
                 if let Some(other_unit) = output_collisions.insert(output.path.clone(), unit) {
                     if unit.mode.is_doc() {
                         // See https://github.com/rust-lang/rust/issues/56169
                         // and https://github.com/rust-lang/rust/issues/61378
-                        if self.is_primary_package(unit) {
-                            // This has been an error since before 1.0, so it
-                            // is not a warning like the other situations.
-                            doc_collision_error(unit, other_unit)?;
-                        }
                         report_collision(unit, other_unit, &output.path, rustdoc_suggestion)?;
                     } else {
                         report_collision(unit, other_unit, &output.path, suggestion)?;

tests/testsuite/doc.rs

@@ -271,14 +271,19 @@ fn doc_multiple_targets_same_name() {
         .build();
 
     p.cargo("doc --workspace")
-        .with_status(101)
-        .with_stderr(
+        .with_stderr_unordered(
             "\
-error: document output filename collision
-The bin `foo_lib` in package `foo v0.1.0 ([ROOT]/foo/foo)` has the same name as \
-the lib `foo_lib` in package `bar v0.1.0 ([ROOT]/foo/bar)`.
-Only one may be documented at once since they output to the same path.
-Consider documenting only one, renaming one, or marking one with `doc = false` in Cargo.toml.
+warning: output filename collision.
+The bin target `foo_lib` in package `foo v0.1.0 ([ROOT]/foo/foo)` \
+has the same output filename as the lib target `foo_lib` in package \
+`bar v0.1.0 ([ROOT]/foo/bar)`.
+Colliding filename is: [ROOT]/foo/target/doc/foo_lib/index.html
+The targets should have unique names.
+This is a known bug where multiple crates with the same name use
+the same path; see <https://github.com/rust-lang/cargo/issues/6313>.
+[DOCUMENTING] bar v0.1.0 ([ROOT]/foo/bar)
+[DOCUMENTING] foo v0.1.0 ([ROOT]/foo/foo)
+[FINISHED] [..]
 ",
         )
         .run();