Fill explicit lib declaration with default values (#38)

* Move `autolib` test to a dedicated file

* tests/autolib: Remove unnecessary manifest entries

We only care about the library auto-discovery here, the rest is just noise.

* Fill explicit `lib` declaration with default values

Previously, it was only possible to either use the auto-discovered lib target or explicitly declare one. In reality, cargo merges the definitions though. It is for example possible to rely on the auto-discovered `src/lib.rs`, but rename the library via `lib.name`.

This commit changes the `lib = Some(_)` code path to assign proper defaults to the `name`, `path`, `edition`, and `crate_type` fields unless they are explicitly specified, which matches the behavior from cargo.

src/lib.rs

@@ -268,7 +268,39 @@ impl<Metadata: for<'a> Deserialize<'a>> Manifest<Metadata> {
             };
 
             if let Some(ref mut lib) = self.lib {
-                lib.required_features.clear(); // not applicable
+                // Use `lib.name` if it's set, otherwise use `package.name` with dashes replaced by underscores
+                // (see <https://doc.rust-lang.org/cargo/reference/cargo-targets.html#the-name-field>).
+                if lib.name.is_none() {
+                    lib.name = Some(package.name.replace('-', "_"));
+                }
+
+                // Use `lib.path` if it's set, otherwise use `src/lib.rs` if it exists, otherwise return an error
+                // (see https://doc.rust-lang.org/cargo/reference/cargo-targets.html#the-path-field).
+                if lib.path.is_none() {
+                    if src.contains("lib.rs") {
+                        lib.path = Some("src/lib.rs".to_string());
+                    } else {
+                        let msg =
+                            "can't find library, rename file to `src/lib.rs` or specify lib.path";
+                        return Err(Error::Other(msg.to_string()));
+                    }
+                }
+
+                // Use `lib.edition` if it's set, otherwise use `package.edition` unless it's inherited
+                // (see https://doc.rust-lang.org/cargo/reference/cargo-targets.html#the-edition-field).
+                if lib.edition.is_none() {
+                    lib.edition = edition;
+                }
+
+                // Use `lib.crate_type` if it's set, otherwise use `["lib"]`
+                // (see https://doc.rust-lang.org/cargo/reference/cargo-targets.html#the-crate-type-field).
+                if lib.crate_type.is_none() {
+                    lib.crate_type = Some(vec!["lib".to_string()]);
+                }
+
+                // `lib.required-features` has no effect on `[lib]`
+                // (see https://doc.rust-lang.org/cargo/reference/cargo-targets.html#the-required-features-field).
+                lib.required_features.clear();
             } else if src.contains("lib.rs") {
                 self.lib = Some(Product {
                     name: Some(package.name.replace('-', "_")),

tests/autolib.rs

@@ -0,0 +1,51 @@
+use cargo_manifest::Manifest;
+
+#[test]
+fn test_bin() {
+    let m = Manifest::from_path("tests/autolib/bin/Cargo.toml").unwrap();
+    assert!(m.lib.is_none());
+}
+
+#[test]
+fn test_lib_rs() {
+    let m = Manifest::from_path("tests/autolib/lib_rs/Cargo.toml").unwrap();
+
+    let lib = m.lib.unwrap();
+    assert_eq!(lib.path.as_deref(), Some("src/lib.rs"));
+    assert_eq!(lib.name.as_deref(), Some("auto_lib"));
+
+    insta::assert_debug_snapshot!(lib);
+}
+
+#[test]
+fn test_name_override() {
+    let m = Manifest::from_path("tests/autolib/name_override/Cargo.toml").unwrap();
+
+    let lib = m.lib.unwrap();
+    assert_eq!(lib.path.as_deref(), Some("src/lib.rs"));
+    assert_eq!(lib.name.as_deref(), Some("foo"));
+
+    insta::assert_debug_snapshot!(lib);
+}
+
+#[test]
+fn test_path_override() {
+    let m = Manifest::from_path("tests/autolib/path_override/Cargo.toml").unwrap();
+
+    let lib = m.lib.unwrap();
+    assert_eq!(lib.path.as_deref(), Some("src/foo.rs"));
+    assert_eq!(lib.name.as_deref(), Some("auto_lib"));
+
+    insta::assert_debug_snapshot!(lib);
+}
+
+#[test]
+fn test_other_override() {
+    let m = Manifest::from_path("tests/autolib/other_override/Cargo.toml").unwrap();
+
+    let lib = m.lib.unwrap();
+    assert!(!lib.test);
+    assert!(lib.proc_macro);
+
+    insta::assert_debug_snapshot!(lib);
+}

tests/autolib/bin/Cargo.toml

@@ -0,0 +1,3 @@
+[package]
+name = "auto-lib"
+version = "0.1.0"

tests/autolib/bin/src/main.rs

@@ -0,0 +1 @@
+

tests/autolib/lib_rs/Cargo.toml

@@ -0,0 +1,3 @@
+[package]
+name = "auto-lib"
+version = "0.1.0"

tests/autolib/name_override/Cargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "auto-lib"
+version = "0.1.0"
+
+[lib]
+name = "foo"

tests/autolib/other_override/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "auto-lib"
+version = "0.1.0"
+edition = "2018"
+
+[lib]
+proc-macro = true
+test = false

tests/autolib/path_override/Cargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "auto-lib"
+version = "0.1.0"
+
+[lib]
+path = "src/foo.rs"

tests/parse.rs

@@ -36,12 +36,6 @@ fn autobin() {
     insta::assert_debug_snapshot!(m);
 }
 
-#[test]
-fn autolib() {
-    let m = Manifest::from_path("tests/autolib/Cargo.toml").expect("load autolib");
-    insta::assert_debug_snapshot!(m);
-}
-
 #[test]
 fn autobuild() {
     let m = Manifest::from_path("tests/autobuild/Cargo.toml").expect("load autobuild");

tests/snapshots/autolib__lib_rs.snap

@@ -0,0 +1,26 @@
+---
+source: tests/autolib.rs
+expression: lib
+---
+Product {
+    path: Some(
+        "src/lib.rs",
+    ),
+    name: Some(
+        "auto_lib",
+    ),
+    test: true,
+    doctest: true,
+    bench: true,
+    doc: true,
+    plugin: false,
+    proc_macro: false,
+    harness: true,
+    edition: None,
+    required_features: [],
+    crate_type: Some(
+        [
+            "lib",
+        ],
+    ),
+}

tests/snapshots/autolib__name_override.snap

@@ -0,0 +1,26 @@
+---
+source: tests/autolib.rs
+expression: lib
+---
+Product {
+    path: Some(
+        "src/lib.rs",
+    ),
+    name: Some(
+        "foo",
+    ),
+    test: true,
+    doctest: true,
+    bench: true,
+    doc: true,
+    plugin: false,
+    proc_macro: false,
+    harness: true,
+    edition: None,
+    required_features: [],
+    crate_type: Some(
+        [
+            "lib",
+        ],
+    ),
+}

tests/snapshots/autolib__other_override.snap

@@ -0,0 +1,28 @@
+---
+source: tests/autolib.rs
+expression: lib
+---
+Product {
+    path: Some(
+        "src/lib.rs",
+    ),
+    name: Some(
+        "auto_lib",
+    ),
+    test: false,
+    doctest: true,
+    bench: true,
+    doc: true,
+    plugin: false,
+    proc_macro: true,
+    harness: true,
+    edition: Some(
+        E2018,
+    ),
+    required_features: [],
+    crate_type: Some(
+        [
+            "lib",
+        ],
+    ),
+}

tests/snapshots/autolib__path_override.snap

@@ -0,0 +1,26 @@
+---
+source: tests/autolib.rs
+expression: lib
+---
+Product {
+    path: Some(
+        "src/foo.rs",
+    ),
+    name: Some(
+        "auto_lib",
+    ),
+    test: true,
+    doctest: true,
+    bench: true,
+    doc: true,
+    plugin: false,
+    proc_macro: false,
+    harness: true,
+    edition: None,
+    required_features: [],
+    crate_type: Some(
+        [
+            "lib",
+        ],
+    ),
+}

tests/snapshots/parse__metadata.snap

@@ -59,7 +59,9 @@ Manifest {
             path: Some(
                 "lib.rs",
             ),
-            name: None,
+            name: Some(
+                "metadata",
+            ),
             test: true,
             doctest: true,
             bench: true,
@@ -69,7 +71,11 @@ Manifest {
             harness: true,
             edition: None,
             required_features: [],
-            crate_type: None,
+            crate_type: Some(
+                [
+                    "lib",
+                ],
+            ),
         },
     ),
     profile: None,