Auto merge of #14591 - epage:autolib, r=weihanglo

feat(toml): Add `autolib`

### What does this PR try to resolve?

PR #5335 added `autobins`, etc for #5330.  Nowhere in there is
discussion of `autolib`.

Cargo script disables support for additional build-targets by disabling
discovery.
Except we don't have a way to disable discovery of `autolib`, leading to #14476.
By adding `autolib`, we can continue in that direction.

This also allows us to bypass inferring of libs on published packages,
like all other build-targets which were handled in #13849.

Fixes #14476

### How should we test and review this PR?

### Additional information

As this seems fairly low controversy, this insta-stabilizes the field.
In prior versions of Cargo, users will get an "unused manifest key"
warning.
For packages where this is set by `cargo publish`, the warning will be suppressed and things will work as normal.
For `cargo vendor`, the same except there will be some churn in the
vendored source as this field will now be set.
For local development, it should be rare to set `autolib` so the lack of
error by discovering a file when this is set shouldn't be a problem.

Cargo.lock

@@ -462,7 +462,7 @@ dependencies = [
 
 [[package]]
 name = "cargo-util-schemas"
-version = "0.6.1"
+version = "0.7.0"
 dependencies = [
  "semver",
  "serde",

Cargo.toml

@@ -33,7 +33,7 @@ cargo-platform = { path = "crates/cargo-platform", version = "0.1.5" }
 cargo-test-macro = { version = "0.3.0", path = "crates/cargo-test-macro" }
 cargo-test-support = { version = "0.5.0", path = "crates/cargo-test-support" }
 cargo-util = { version = "0.2.14", path = "crates/cargo-util" }
-cargo-util-schemas = { version = "0.6.0", path = "crates/cargo-util-schemas" }
+cargo-util-schemas = { version = "0.7.0", path = "crates/cargo-util-schemas" }
 cargo_metadata = "0.18.1"
 clap = "4.5.18"
 clap_complete = { version = "4.5.29", features = ["unstable-dynamic"] }

crates/cargo-util-schemas/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "cargo-util-schemas"
-version = "0.6.1"
+version = "0.7.0"
 rust-version = "1.81"  # MSRV:1
 edition.workspace = true
 license.workspace = true

crates/cargo-util-schemas/src/manifest/mod.rs

@@ -173,6 +173,7 @@ pub struct TomlPackage {
     pub publish: Option<InheritableVecStringOrBool>,
     pub workspace: Option<String>,
     pub im_a_teapot: Option<bool>,
+    pub autolib: Option<bool>,
     pub autobins: Option<bool>,
     pub autoexamples: Option<bool>,
     pub autotests: Option<bool>,
@@ -217,6 +218,7 @@ impl TomlPackage {
             publish: None,
             workspace: None,
             im_a_teapot: None,
+            autolib: None,
             autobins: None,
             autoexamples: None,
             autotests: None,

src/cargo/util/toml/embedded.rs

@@ -8,7 +8,13 @@ use crate::GlobalContext;
 
 const DEFAULT_EDITION: crate::core::features::Edition =
     crate::core::features::Edition::LATEST_STABLE;
-const AUTO_FIELDS: &[&str] = &["autobins", "autoexamples", "autotests", "autobenches"];
+const AUTO_FIELDS: &[&str] = &[
+    "autolib",
+    "autobins",
+    "autoexamples",
+    "autotests",
+    "autobenches",
+];
 
 pub(super) fn expand_manifest(
     content: &str,
@@ -289,6 +295,7 @@ path = "/home/me/test.rs"
 autobenches = false
 autobins = false
 autoexamples = false
+autolib = false
 autotests = false
 build = false
 edition = "2021"
@@ -324,6 +331,7 @@ time = "0.1.25"
 autobenches = false
 autobins = false
 autoexamples = false
+autolib = false
 autotests = false
 build = false
 edition = "2021"
@@ -359,6 +367,7 @@ time = "0.1.25"
 autobenches = false
 autobins = false
 autoexamples = false
+autolib = false
 autotests = false
 build = false
 edition = "2021"

src/cargo/util/toml/mod.rs

@@ -334,6 +334,7 @@ fn normalize_toml(
             package_root,
             &original_package.name,
             edition,
+            original_package.autolib,
             warnings,
         )?;
         normalized_toml.bin = Some(targets::normalize_bins(
@@ -624,6 +625,7 @@ fn normalize_package_toml<'a>(
             .map(manifest::InheritableField::Value),
         workspace: original_package.workspace.clone(),
         im_a_teapot: original_package.im_a_teapot.clone(),
+        autolib: Some(false),
         autobins: Some(false),
         autoexamples: Some(false),
         autotests: Some(false),

src/cargo/util/toml/targets.rs

@@ -129,48 +129,63 @@ pub fn normalize_lib(
     package_root: &Path,
     package_name: &str,
     edition: Edition,
+    autodiscover: Option<bool>,
     warnings: &mut Vec<String>,
 ) -> CargoResult<Option<TomlLibTarget>> {
-    let inferred = inferred_lib(package_root);
-    let lib = original_lib.cloned().or_else(|| {
-        inferred.as_ref().map(|lib| TomlTarget {
-            path: Some(PathValue(lib.clone())),
-            ..TomlTarget::new()
-        })
-    });
-    let Some(mut lib) = lib else { return Ok(None) };
-    lib.name
-        .get_or_insert_with(|| package_name.replace("-", "_"));
+    if is_normalized(original_lib, autodiscover) {
+        let Some(lib) = original_lib.cloned() else {
+            return Ok(None);
+        };
 
-    // Check early to improve error messages
-    validate_lib_name(&lib, warnings)?;
+        // Check early to improve error messages
+        validate_lib_name(&lib, warnings)?;
 
-    validate_proc_macro(&lib, "library", edition, warnings)?;
-    validate_crate_types(&lib, "library", edition, warnings)?;
+        validate_proc_macro(&lib, "library", edition, warnings)?;
+        validate_crate_types(&lib, "library", edition, warnings)?;
 
-    if lib.path.is_none() {
-        if let Some(inferred) = inferred {
-            lib.path = Some(PathValue(inferred));
-        } else {
-            let name = name_or_panic(&lib);
-            let legacy_path = Path::new("src").join(format!("{name}.rs"));
-            if edition == Edition::Edition2015 && package_root.join(&legacy_path).exists() {
-                warnings.push(format!(
-                    "path `{}` was erroneously implicitly accepted for library `{name}`,\n\
-                     please rename the file to `src/lib.rs` or set lib.path in Cargo.toml",
-                    legacy_path.display(),
-                ));
-                lib.path = Some(PathValue(legacy_path));
+        Ok(Some(lib))
+    } else {
+        let inferred = inferred_lib(package_root);
+        let lib = original_lib.cloned().or_else(|| {
+            inferred.as_ref().map(|lib| TomlTarget {
+                path: Some(PathValue(lib.clone())),
+                ..TomlTarget::new()
+            })
+        });
+        let Some(mut lib) = lib else { return Ok(None) };
+        lib.name
+            .get_or_insert_with(|| package_name.replace("-", "_"));
+
+        // Check early to improve error messages
+        validate_lib_name(&lib, warnings)?;
+
+        validate_proc_macro(&lib, "library", edition, warnings)?;
+        validate_crate_types(&lib, "library", edition, warnings)?;
+
+        if lib.path.is_none() {
+            if let Some(inferred) = inferred {
+                lib.path = Some(PathValue(inferred));
             } else {
-                anyhow::bail!(
-                    "can't find library `{name}`, \
+                let name = name_or_panic(&lib);
+                let legacy_path = Path::new("src").join(format!("{name}.rs"));
+                if edition == Edition::Edition2015 && package_root.join(&legacy_path).exists() {
+                    warnings.push(format!(
+                        "path `{}` was erroneously implicitly accepted for library `{name}`,\n\
+                     please rename the file to `src/lib.rs` or set lib.path in Cargo.toml",
+                        legacy_path.display(),
+                    ));
+                    lib.path = Some(PathValue(legacy_path));
+                } else {
+                    anyhow::bail!(
+                        "can't find library `{name}`, \
                      rename file to `src/lib.rs` or specify lib.path",
-                )
+                    )
+                }
             }
         }
-    }
 
-    Ok(Some(lib))
+        Ok(Some(lib))
+    }
 }
 
 #[tracing::instrument(skip_all)]
@@ -239,7 +254,7 @@ pub fn normalize_bins(
     errors: &mut Vec<String>,
     has_lib: bool,
 ) -> CargoResult<Vec<TomlBinTarget>> {
-    if is_normalized(toml_bins, autodiscover) {
+    if are_normalized(toml_bins, autodiscover) {
         let toml_bins = toml_bins.cloned().unwrap_or_default();
         for bin in &toml_bins {
             validate_bin_name(bin, warnings)?;
@@ -526,7 +541,15 @@ fn to_bench_targets(
     Ok(result)
 }
 
-fn is_normalized(toml_targets: Option<&Vec<TomlTarget>>, autodiscover: Option<bool>) -> bool {
+fn is_normalized(toml_target: Option<&TomlTarget>, autodiscover: Option<bool>) -> bool {
+    are_normalized_(toml_target.map(std::slice::from_ref), autodiscover)
+}
+
+fn are_normalized(toml_targets: Option<&Vec<TomlTarget>>, autodiscover: Option<bool>) -> bool {
+    are_normalized_(toml_targets.map(|v| v.as_slice()), autodiscover)
+}
+
+fn are_normalized_(toml_targets: Option<&[TomlTarget]>, autodiscover: Option<bool>) -> bool {
     if autodiscover != Some(false) {
         return false;
     }
@@ -579,7 +602,7 @@ fn normalize_targets_with_legacy_path(
     legacy_path: &mut dyn FnMut(&TomlTarget) -> Option<PathBuf>,
     autodiscover_flag_name: &str,
 ) -> CargoResult<Vec<TomlTarget>> {
-    if is_normalized(toml_targets, autodiscover) {
+    if are_normalized(toml_targets, autodiscover) {
         let toml_targets = toml_targets.cloned().unwrap_or_default();
         for target in &toml_targets {
             // Check early to improve error messages

src/doc/src/reference/cargo-targets.md

@@ -323,13 +323,14 @@ configuration tables, such as `[lib]`, `[[bin]]`, `[[test]]`, `[[bench]]`, or
 standard directory layout.
 
 The automatic target discovery can be disabled so that only manually
-configured targets will be built. Setting the keys `autobins`, `autoexamples`,
+configured targets will be built. Setting the keys `autolib`, `autobins`, `autoexamples`,
 `autotests`, or `autobenches` to `false` in the `[package]` section will
 disable auto-discovery of the corresponding target type.
 
 ```toml
 [package]
 # ...
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false
@@ -363,6 +364,9 @@ autobins = false
 > is `false` if at least one target is manually defined in `Cargo.toml`.
 > Beginning with the 2018 edition, the default is always `true`.
 
+> **MSRV:** Respected as of 1.27 for `autobins`, `autoexamples`, `autotests`, and `autobenches`
+
+> **MSRV:** Respected as of 1.83 for `autolib`
 
 [Build cache]: ../guide/build-cache.md
 [Rust Edition]: ../../edition-guide/index.html

src/doc/src/reference/manifest.md

@@ -30,6 +30,7 @@ Every manifest file consists of the following sections:
   * [`publish`](#the-publish-field) --- Can be used to prevent publishing the package.
   * [`metadata`](#the-metadata-table) --- Extra settings for external tools.
   * [`default-run`](#the-default-run-field) --- The default binary to run by [`cargo run`].
+  * [`autolib`](cargo-targets.md#target-auto-discovery) --- Disables library auto discovery.
   * [`autobins`](cargo-targets.md#target-auto-discovery) --- Disables binary auto discovery.
   * [`autoexamples`](cargo-targets.md#target-auto-discovery) --- Disables example auto discovery.
   * [`autotests`](cargo-targets.md#target-auto-discovery) --- Disables test auto discovery.

src/doc/src/reference/unstable.md

@@ -1314,7 +1314,7 @@ Inferred / defaulted manifest fields:
 
 Disallowed manifest fields:
 - `[workspace]`, `[lib]`, `[[bin]]`, `[[example]]`, `[[test]]`, `[[bench]]`
-- `package.workspace`, `package.build`, `package.links`, `package.autobins`, `package.autoexamples`, `package.autotests`, `package.autobenches`
+- `package.workspace`, `package.build`, `package.links`, `package.autolib`, `package.autobins`, `package.autoexamples`, `package.autotests`, `package.autobenches`
 
 The default `CARGO_TARGET_DIR` for single-file packages is at `$CARGO_HOME/target/<hash>`:
 - Avoid conflicts from multiple single-file packages being in the same directory

tests/testsuite/artifact_dep.rs

@@ -2272,6 +2272,7 @@ name = "foo"
 version = "0.1.0"
 authors = []
 build = false
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false

tests/testsuite/features2.rs

@@ -1800,6 +1800,7 @@ name = "a"
 version = "0.1.0"
 authors = ["Zzz"]
 build = false
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false

tests/testsuite/features_namespaced.rs

@@ -985,6 +985,7 @@ edition = "2015"
 name = "foo"
 version = "0.1.0"
 build = false
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false
@@ -1112,6 +1113,7 @@ edition = "2015"
 name = "foo"
 version = "0.1.0"
 build = false
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false

tests/testsuite/inheritable_workspace_fields.rs

@@ -224,6 +224,7 @@ include = [
     "Cargo.toml",
 ]
 publish = true
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false
@@ -394,6 +395,7 @@ name = "bar"
 version = "0.2.0"
 authors = []
 build = false
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false
@@ -533,6 +535,7 @@ name = "bar"
 version = "0.2.0"
 authors = []
 build = false
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false
@@ -793,6 +796,7 @@ include = [
     "README.md",
 ]
 publish = true
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false
@@ -966,6 +970,7 @@ name = "bar"
 version = "0.2.0"
 authors = []
 build = false
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false

tests/testsuite/package.rs

@@ -1334,6 +1334,7 @@ version = "0.0.1"
 authors = []
 build = false
 exclude = ["*.txt"]
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false
@@ -1419,6 +1420,7 @@ name = "bar"
 version = "0.1.0"
 authors = []
 build = false
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false
@@ -1496,6 +1498,7 @@ edition = "2015"
 name = "foo"
 version = "0.0.1"
 build = false
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false
@@ -1524,6 +1527,7 @@ edition = "2015"
 name = "foo"
 version = "0.0.1"
 build = false
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false
@@ -2986,6 +2990,7 @@ edition = "2021"
 name = "bar"
 version = "0.1.0"
 build = false
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false
@@ -3015,6 +3020,7 @@ edition = "2015"
 name = "baz"
 version = "0.1.0"
 build = false
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false
@@ -3087,6 +3093,7 @@ version = "0.0.1"
 authors = []
 build = false
 exclude = ["*.txt"]
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false
@@ -3189,6 +3196,7 @@ name = "foo"
 version = "0.0.1"
 authors = []
 build = false
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false
@@ -3304,6 +3312,7 @@ name = "foo"
 version = "0.0.1"
 authors = []
 build = false
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false
@@ -3496,6 +3505,7 @@ version = "0.0.1"
 authors = []
 build = false
 exclude = ["*.txt"]
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false
@@ -3902,6 +3912,7 @@ name = "foo"
 version = "0.0.1"
 authors = []
 build = "src/build.rs"
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false
@@ -3996,6 +4007,7 @@ include = [
     "src/lib.rs",
     "build.rs",
 ]
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false
@@ -4072,6 +4084,7 @@ version = "0.0.1"
 authors = []
 build = false
 include = ["src/lib.rs"]
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false
@@ -4151,6 +4164,7 @@ include = [
     "src/lib.rs",
     "build.rs",
 ]
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false
@@ -4228,6 +4242,7 @@ version = "0.0.1"
 authors = []
 build = false
 include = ["src/lib.rs"]
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false
@@ -4312,6 +4327,7 @@ include = [
     "src/main.rs",
     "src/lib.rs",
 ]
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false
@@ -4392,6 +4408,7 @@ version = "0.0.1"
 authors = []
 build = false
 include = ["src/main.rs"]
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false
@@ -4479,6 +4496,7 @@ include = [
     "src/main.rs",
     "src/lib.rs",
 ]
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false
@@ -4562,6 +4580,7 @@ version = "0.0.1"
 authors = []
 build = false
 include = ["src/main.rs"]
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false
@@ -4655,6 +4674,7 @@ include = [
     "tests/test_foo.rs",
     "benches/bench_foo.rs",
 ]
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false
@@ -4753,6 +4773,7 @@ version = "0.0.1"
 authors = []
 build = false
 include = ["src/lib.rs"]
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false
@@ -4858,6 +4879,7 @@ include = [
     "tests/test_foo.rs",
     "benches/bench_foo.rs",
 ]
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false
@@ -4968,6 +4990,7 @@ version = "0.0.1"
 authors = []
 build = false
 include = ["src/lib.rs"]
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false
@@ -5066,6 +5089,7 @@ name = "foo"
 version = "0.0.1"
 authors = []
 build = false
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false
@@ -5275,6 +5299,7 @@ name = "level1"
 version = "0.0.1"
 authors = []
 build = false
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false

tests/testsuite/publish.rs

@@ -1583,6 +1583,7 @@ You may press ctrl-c to skip waiting; the crate should be available shortly.
                      version = \"0.1.0\"\n\
                      authors = []\n\
                      build = false\n\
+                     autolib = false\n\
                      autobins = false\n\
                      autoexamples = false\n\
                      autotests = false\n\
@@ -1963,6 +1964,7 @@ name = "foo"
 version = "0.1.0"
 authors = []
 build = false
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false

tests/testsuite/script.rs

@@ -813,6 +813,34 @@ Hello world!
         .run();
 }
 
+#[cargo_test]
+fn test_no_autolib() {
+    let script = r#"#!/usr/bin/env cargo
+
+fn main() {
+    println!("Hello world!");
+}"#;
+    let p = cargo_test_support::project()
+        .file("script.rs", script)
+        .file("src/lib.rs", r#"compile_error!{"must not be built"}"#)
+        .build();
+
+    p.cargo("-Zscript -v script.rs --help")
+        .masquerade_as_nightly_cargo(&["script"])
+        .with_stdout_data(str![[r#"
+Hello world!
+
+"#]])
+        .with_stderr_data(str![[r#"
+[WARNING] `package.edition` is unspecified, defaulting to `2021`
+[COMPILING] script v0.0.0 ([ROOT]/foo)
+[FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s
+[RUNNING] `[ROOT]/home/.cargo/target/[HASH]/debug/script[EXE] --help`
+
+"#]])
+        .run();
+}
+
 #[cargo_test]
 fn implicit_target_dir() {
     let script = ECHO_SCRIPT;

tests/testsuite/vendor.rs

@@ -294,6 +294,7 @@ include = [
     "src/lib.rs",
     "build.rs",
 ]
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false
@@ -379,6 +380,7 @@ version = "0.0.1"
 authors = []
 build = false
 include = ["src/lib.rs"]
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false
@@ -467,6 +469,7 @@ include = [
     "src/main.rs",
     "src/lib.rs",
 ]
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false
@@ -556,6 +559,7 @@ version = "0.0.1"
 authors = []
 build = false
 include = ["src/main.rs"]
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false
@@ -650,6 +654,7 @@ include = [
     "tests/test_foo.rs",
     "benches/bench_foo.rs",
 ]
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false
@@ -754,6 +759,7 @@ version = "0.0.1"
 authors = []
 build = false
 include = ["src/lib.rs"]
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false
@@ -1527,6 +1533,7 @@ name = "git_dep"
 version = "0.0.1"
 authors = []
 build = false
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false
@@ -1542,27 +1549,27 @@ path = "src/lib.rs"
 
 [[example]]
 name = "a"
-path = [..]
+path = "examples/a.rs"
 
 [[example]]
 name = "b"
-path = [..]
+path = "examples/b.rs"
 
 [[example]]
 name = "c"
-path = [..]
+path = "examples/c.rs"
 
 [[example]]
 name = "x"
-path = [..]
+path = "examples/x.rs"
 
 [[example]]
 name = "y"
-path = [..]
+path = "examples/y.rs"
 
 [[example]]
 name = "z"
-path = [..]
+path = "examples/z.rs"
 
 "##]],
     );

tests/testsuite/weak_dep_features.rs

@@ -630,6 +630,7 @@ edition = "2015"
 name = "foo"
 version = "0.1.0"
 build = false
+autolib = false
 autobins = false
 autoexamples = false
 autotests = false