Auto merge of #8824 - ehuss:normalize-source-master, r=alexcrichton

Normalize SourceID in `cargo metadata`.

The SourceID in `cargo metadata` can have different values, but they can be equivalent in Cargo. This results in different serialized forms, which prevents comparing the ID strings. In this particular case, `SourceKind::Git(GitReference::Branch("master"))` is equivalent to `SourceKind::Git(GitReference::DefaultBranch)`, but they serialize differently.

The reason these end up differently is because the `SourceId` for a `Package` is created from the `Dependency` declaration. But the `SourceId` in `Cargo.lock` comes from the deserialized file. If you have an explicit `branch = "master"` in the dependency, then versions prior to 1.47 would *not* include `?branch=master` in `Cargo.lock`. However, since 1.47, internally Cargo will use `GitReference::Branch("master")`.

Conversely, if you have a new `Cargo.lock` (with `?branch=master`), and then *remove* the explicit `branch="master"` from `Cargo.toml`, you'll end up with another mismatch in `cargo metadata`.

The solution here is to use the variant from the `Package` when serializing the resolver in `cargo metadata`. I chose this since the `Package` variant is displayed on other JSON messages (like artifact messages), and I think this is the only place that the resolver variants are exposed (other than `Cargo.lock` itself).

I'm not convinced that this was entirely intended, since there is [code to avoid this](https://github.com/rust-lang/cargo/blob/6a38927551df9bbe2dea340bf92d3e53abccf890/src/cargo/core/resolver/encode.rs#L688-L695), and at the time #8522 landed, I did not realize this would change the V2 lock format. However, it's probably too late to try to reverse that, and I don't think there are any other problems other than this `cargo metadata` inconsistency.

Fixes #8756

Author: bors

src/cargo/ops/cargo_output_metadata.rs

@@ -180,6 +180,21 @@ fn build_resolve_graph_r(
     if node_map.contains_key(&pkg_id) {
         return;
     }
+    // This normalizes the IDs so that they are consistent between the
+    // `packages` array and the `resolve` map. This is a bit of a hack to
+    // compensate for the fact that
+    // SourceKind::Git(GitReference::Branch("master")) is the same as
+    // SourceKind::Git(GitReference::DefaultBranch). We want IDs in the JSON
+    // to be opaque, and compare with basic string equality, so this will
+    // always prefer the style of ID in the Package instead of the resolver.
+    // Cargo generally only exposes PackageIds from the Package struct, and
+    // AFAIK this is the only place where the resolver variant is exposed.
+    //
+    // This diverges because the SourceIds created for Packages are built
+    // based on the Dependency declaration, but the SourceIds in the resolver
+    // are deserialized from Cargo.lock. Cargo.lock may have been generated by
+    // an older (or newer!) version of Cargo which uses a different style.
+    let normalize_id = |id| -> PackageId { *package_map.get_key_value(&id).unwrap().0 };
     let features = resolve.features(pkg_id).to_vec();
 
     let deps: Vec<Dep> = resolve
@@ -203,15 +218,15 @@ fn build_resolve_graph_r(
                 .and_then(|lib_target| resolve.extern_crate_name(pkg_id, dep_id, lib_target).ok())
                 .map(|name| Dep {
                     name,
-                    pkg: dep_id,
+                    pkg: normalize_id(dep_id),
                     dep_kinds,
                 })
         })
         .collect();
-    let dumb_deps: Vec<PackageId> = deps.iter().map(|dep| dep.pkg).collect();
+    let dumb_deps: Vec<PackageId> = deps.iter().map(|dep| normalize_id(dep.pkg)).collect();
     let to_visit = dumb_deps.clone();
     let node = MetadataResolveNode {
-        id: pkg_id,
+        id: normalize_id(pkg_id),
         dependencies: dumb_deps,
         deps,
         features,

tests/testsuite/git.rs

@@ -3020,3 +3020,209 @@ warning: [..]
         )
         .run();
 }
+
+#[cargo_test]
+fn metadata_master_consistency() {
+    // SourceId consistency in the `cargo metadata` output when `master` is
+    // explicit or implicit, using new or old Cargo.lock.
+    let (git_project, git_repo) = git::new_repo("bar", |project| {
+        project
+            .file("Cargo.toml", &basic_manifest("bar", "1.0.0"))
+            .file("src/lib.rs", "")
+    });
+    let bar_hash = git_repo.head().unwrap().target().unwrap().to_string();
+
+    // Explicit branch="master" with a lock file created before 1.47 (does not contain ?branch=master).
+    let p = project()
+        .file(
+            "Cargo.toml",
+            &format!(
+                r#"
+                [package]
+                name = "foo"
+                version = "0.1.0"
+
+                [dependencies]
+                bar = {{ git = "{}", branch = "master" }}
+            "#,
+                git_project.url()
+            ),
+        )
+        .file(
+            "Cargo.lock",
+            &format!(
+                r#"
+                    [[package]]
+                    name = "bar"
+                    version = "1.0.0"
+                    source = "git+{}#{}"
+
+                    [[package]]
+                    name = "foo"
+                    version = "0.1.0"
+                    dependencies = [
+                     "bar",
+                    ]
+                "#,
+                git_project.url(),
+                bar_hash,
+            ),
+        )
+        .file("src/lib.rs", "")
+        .build();
+
+    let metadata = |bar_source| -> String {
+        r#"
+            {
+              "packages": [
+                {
+                  "name": "bar",
+                  "version": "1.0.0",
+                  "id": "bar 1.0.0 (__BAR_SOURCE__#__BAR_HASH__)",
+                  "license": null,
+                  "license_file": null,
+                  "description": null,
+                  "source": "__BAR_SOURCE__#__BAR_HASH__",
+                  "dependencies": [],
+                  "targets": "{...}",
+                  "features": {},
+                  "manifest_path": "[..]",
+                  "metadata": null,
+                  "publish": null,
+                  "authors": [],
+                  "categories": [],
+                  "keywords": [],
+                  "readme": null,
+                  "repository": null,
+                  "homepage": null,
+                  "documentation": null,
+                  "edition": "2015",
+                  "links": null
+                },
+                {
+                  "name": "foo",
+                  "version": "0.1.0",
+                  "id": "foo 0.1.0 [..]",
+                  "license": null,
+                  "license_file": null,
+                  "description": null,
+                  "source": null,
+                  "dependencies": [
+                    {
+                      "name": "bar",
+                      "source": "__BAR_SOURCE__",
+                      "req": "*",
+                      "kind": null,
+                      "rename": null,
+                      "optional": false,
+                      "uses_default_features": true,
+                      "features": [],
+                      "target": null,
+                      "registry": null
+                    }
+                  ],
+                  "targets": "{...}",
+                  "features": {},
+                  "manifest_path": "[..]",
+                  "metadata": null,
+                  "publish": null,
+                  "authors": [],
+                  "categories": [],
+                  "keywords": [],
+                  "readme": null,
+                  "repository": null,
+                  "homepage": null,
+                  "documentation": null,
+                  "edition": "2015",
+                  "links": null
+                }
+              ],
+              "workspace_members": [
+                "foo 0.1.0 [..]"
+              ],
+              "resolve": {
+                "nodes": [
+                  {
+                    "id": "bar 1.0.0 (__BAR_SOURCE__#__BAR_HASH__)",
+                    "dependencies": [],
+                    "deps": [],
+                    "features": []
+                  },
+                  {
+                    "id": "foo 0.1.0 [..]",
+                    "dependencies": [
+                      "bar 1.0.0 (__BAR_SOURCE__#__BAR_HASH__)"
+                    ],
+                    "deps": [
+                      {
+                        "name": "bar",
+                        "pkg": "bar 1.0.0 (__BAR_SOURCE__#__BAR_HASH__)",
+                        "dep_kinds": [
+                          {
+                            "kind": null,
+                            "target": null
+                          }
+                        ]
+                      }
+                    ],
+                    "features": []
+                  }
+                ],
+                "root": "foo 0.1.0 [..]"
+              },
+              "target_directory": "[..]",
+              "version": 1,
+              "workspace_root": "[..]",
+              "metadata": null
+            }
+        "#
+        .replace("__BAR_SOURCE__", bar_source)
+        .replace("__BAR_HASH__", &bar_hash)
+    };
+
+    let bar_source = format!("git+{}?branch=master", git_project.url());
+    p.cargo("metadata").with_json(&metadata(&bar_source)).run();
+
+    // Conversely, remove branch="master" from Cargo.toml, but use a new Cargo.lock that has ?branch=master.
+    let p = project()
+        .file(
+            "Cargo.toml",
+            &format!(
+                r#"
+                [package]
+                name = "foo"
+                version = "0.1.0"
+
+                [dependencies]
+                bar = {{ git = "{}" }}
+            "#,
+                git_project.url()
+            ),
+        )
+        .file(
+            "Cargo.lock",
+            &format!(
+                r#"
+                    [[package]]
+                    name = "bar"
+                    version = "1.0.0"
+                    source = "git+{}?branch=master#{}"
+
+                    [[package]]
+                    name = "foo"
+                    version = "0.1.0"
+                    dependencies = [
+                     "bar",
+                    ]
+                "#,
+                git_project.url(),
+                bar_hash
+            ),
+        )
+        .file("src/lib.rs", "")
+        .build();
+
+    // No ?branch=master!
+    let bar_source = format!("git+{}", git_project.url());
+    p.cargo("metadata").with_json(&metadata(&bar_source)).run();
+}