Rollup merge of #77249 - jyn514:private-links, r=Manishearth

Separate `private_intra_doc_links` and `broken_intra_doc_links` into separate lints

This is not ideal because it means `deny(broken_intra_doc_links)` will
no longer `deny(private_intra_doc_links)`. However, it can't be fixed
with a new lint group, because `broken` is already in the `rustdoc` lint
group; there would need to be a way to nest groups somehow.

This also removes the early `return` so that the link will be generated
even though it gives a warning.

r? @Manishearth
cc @ecstatic-morse (https://github.com/rust-lang/rust/pull/77242#issuecomment-699565095)

compiler/rustc_lint/src/lib.rs

@@ -305,6 +305,7 @@ fn register_builtins(store: &mut LintStore, no_interleave_lints: bool) {
     add_lint_group!(
         "rustdoc",
         BROKEN_INTRA_DOC_LINKS,
+        PRIVATE_INTRA_DOC_LINKS,
         INVALID_CODEBLOCK_ATTRIBUTES,
         MISSING_DOC_CODE_EXAMPLES,
         PRIVATE_DOC_TESTS

compiler/rustc_session/src/lint/builtin.rs

@@ -1826,6 +1826,17 @@ declare_lint! {
     "failures in resolving intra-doc link targets"
 }
 
+declare_lint! {
+    /// This is a subset of `broken_intra_doc_links` that warns when linking from
+    /// a public item to a private one. This is a `rustdoc` only lint, see the
+    /// documentation in the [rustdoc book].
+    ///
+    /// [rustdoc book]: ../../../rustdoc/lints.html#private_intra_doc_links
+    pub PRIVATE_INTRA_DOC_LINKS,
+    Warn,
+    "linking from a public item to a private one"
+}
+
 declare_lint! {
     /// The `invalid_codeblock_attributes` lint detects code block attributes
     /// in documentation examples that have potentially mis-typed values. This

src/doc/rustdoc/src/lints.md

@@ -62,6 +62,46 @@ help: to link to the function, add parentheses
 
 ```
 
+## private_intra_doc_links
+
+This lint **warns by default**. This lint detects when [intra-doc links] from public to private items.
+For example:
+
+```rust
+/// [private]
+pub fn public() {}
+fn private() {}
+```
+
+This gives a warning that the link will be broken when it appears in your documentation:
+
+```text
+warning: public documentation for `public` links to private item `private`
+ --> priv.rs:1:6
+  |
+1 | /// [private]
+  |      ^^^^^^^ this item is private
+  |
+  = note: `#[warn(private_intra_doc_links)]` on by default
+  = note: this link will resolve properly if you pass `--document-private-items`
+```
+
+Note that this has different behavior depending on whether you pass `--document-private-items` or not!
+If you document private items, then it will still generate a link, despite the warning:
+
+```text
+warning: public documentation for `public` links to private item `private`
+ --> priv.rs:1:6
+  |
+1 | /// [private]
+  |      ^^^^^^^ this item is private
+  |
+  = note: `#[warn(private_intra_doc_links)]` on by default
+  = note: this link resolves only because you passed `--document-private-items`, but will break without
+```
+
+[intra-doc links]: linking-to-items-by-name.html
+
 ## missing_docs
 
 This lint is **allowed by default**. It detects items missing documentation.

src/librustdoc/passes/collect_intra_doc_links.rs

@@ -11,7 +11,10 @@ use rustc_hir::def::{
 use rustc_hir::def_id::DefId;
 use rustc_middle::ty;
 use rustc_resolve::ParentScope;
-use rustc_session::lint;
+use rustc_session::lint::{
+    builtin::{BROKEN_INTRA_DOC_LINKS, PRIVATE_INTRA_DOC_LINKS},
+    Lint,
+};
 use rustc_span::hygiene::MacroKind;
 use rustc_span::symbol::Ident;
 use rustc_span::symbol::Symbol;
@@ -988,7 +991,7 @@ impl LinkCollector<'_, '_> {
         let report_mismatch = |specified: Disambiguator, resolved: Disambiguator| {
             // The resolved item did not match the disambiguator; give a better error than 'not found'
             let msg = format!("incompatible link kind for `{}`", path_str);
-            report_diagnostic(cx, &msg, &item, dox, &link_range, |diag, sp| {
+            let callback = |diag: &mut DiagnosticBuilder<'_>, sp| {
                 let note = format!(
                     "this link resolved to {} {}, which is not {} {}",
                     resolved.article(),
@@ -998,7 +1001,8 @@ impl LinkCollector<'_, '_> {
                 );
                 diag.note(&note);
                 suggest_disambiguator(resolved, diag, path_str, dox, sp, &link_range);
-            });
+            };
+            report_diagnostic(cx, BROKEN_INTRA_DOC_LINKS, &msg, &item, dox, &link_range, callback);
         };
         if let Res::PrimTy(..) = res {
             match disambiguator {
@@ -1055,7 +1059,6 @@ impl LinkCollector<'_, '_> {
                     && !self.cx.tcx.privacy_access_levels(LOCAL_CRATE).is_exported(hir_dst)
                 {
                     privacy_error(cx, &item, &path_str, dox, link_range);
-                    return;
                 }
             }
             let id = register_res(cx, res);
@@ -1417,6 +1420,7 @@ impl Suggestion {
 /// to it.
 fn report_diagnostic(
     cx: &DocContext<'_>,
+    lint: &'static Lint,
     msg: &str,
     item: &Item,
     dox: &str,
@@ -1435,7 +1439,7 @@ fn report_diagnostic(
     let attrs = &item.attrs;
     let sp = span_of_attrs(attrs).unwrap_or(item.source.span());
 
-    cx.tcx.struct_span_lint_hir(lint::builtin::BROKEN_INTRA_DOC_LINKS, hir_id, sp, |lint| {
+    cx.tcx.struct_span_lint_hir(lint, hir_id, sp, |lint| {
         let mut diag = lint.build(msg);
 
         let span = link_range
@@ -1482,6 +1486,7 @@ fn resolution_failure(
 ) {
     report_diagnostic(
         collector.cx,
+        BROKEN_INTRA_DOC_LINKS,
         &format!("unresolved link to `{}`", path_str),
         item,
         dox,
@@ -1695,7 +1700,7 @@ fn anchor_failure(
         ),
     };
 
-    report_diagnostic(cx, &msg, item, dox, &link_range, |diag, sp| {
+    report_diagnostic(cx, BROKEN_INTRA_DOC_LINKS, &msg, item, dox, &link_range, |diag, sp| {
         if let Some(sp) = sp {
             diag.span_label(sp, "contains invalid anchor");
         }
@@ -1734,7 +1739,7 @@ fn ambiguity_error(
         }
     }
 
-    report_diagnostic(cx, &msg, item, dox, &link_range, |diag, sp| {
+    report_diagnostic(cx, BROKEN_INTRA_DOC_LINKS, &msg, item, dox, &link_range, |diag, sp| {
         if let Some(sp) = sp {
             diag.span_label(sp, "ambiguous link");
         } else {
@@ -1784,7 +1789,7 @@ fn privacy_error(
     let msg =
         format!("public documentation for `{}` links to private item `{}`", item_name, path_str);
 
-    report_diagnostic(cx, &msg, item, dox, &link_range, |diag, sp| {
+    report_diagnostic(cx, PRIVATE_INTRA_DOC_LINKS, &msg, item, dox, &link_range, |diag, sp| {
         if let Some(sp) = sp {
             diag.span_label(sp, "this item is private");
         }

src/test/rustdoc-ui/intra-links-private.private.stderr

@@ -4,7 +4,7 @@ warning: public documentation for `DocMe` links to private item `DontDocMe`
 LL | /// docs [DontDocMe]
    |           ^^^^^^^^^ this item is private
    |
-   = note: `#[warn(broken_intra_doc_links)]` on by default
+   = note: `#[warn(private_intra_doc_links)]` on by default
    = note: this link resolves only because you passed `--document-private-items`, but will break without
 
 warning: 1 warning emitted

src/test/rustdoc-ui/intra-links-private.public.stderr

@@ -4,7 +4,7 @@ warning: public documentation for `DocMe` links to private item `DontDocMe`
 LL | /// docs [DontDocMe]
    |           ^^^^^^^^^ this item is private
    |
-   = note: `#[warn(broken_intra_doc_links)]` on by default
+   = note: `#[warn(private_intra_doc_links)]` on by default
    = note: this link will resolve properly if you pass `--document-private-items`
 
 warning: 1 warning emitted

src/test/rustdoc-ui/issue-74134.private.stderr

@@ -4,7 +4,7 @@ warning: public documentation for `public_item` links to private item `PrivateTy
 LL |     /// [`PrivateType`]
    |          ^^^^^^^^^^^^^ this item is private
    |
-   = note: `#[warn(broken_intra_doc_links)]` on by default
+   = note: `#[warn(private_intra_doc_links)]` on by default
    = note: this link resolves only because you passed `--document-private-items`, but will break without
 
 warning: 1 warning emitted

src/test/rustdoc-ui/issue-74134.public.stderr

@@ -4,7 +4,7 @@ warning: public documentation for `public_item` links to private item `PrivateTy
 LL |     /// [`PrivateType`]
    |          ^^^^^^^^^^^^^ this item is private
    |
-   = note: `#[warn(broken_intra_doc_links)]` on by default
+   = note: `#[warn(private_intra_doc_links)]` on by default
    = note: this link will resolve properly if you pass `--document-private-items`
 
 warning: 1 warning emitted

src/test/rustdoc/intra-doc-link-private.rs

@@ -0,0 +1,6 @@
+#![crate_name = "private"]
+// compile-flags: --document-private-items
+/// docs [DontDocMe]
+// @has private/struct.DocMe.html '//*a[@href="../private/struct.DontDocMe.html"]' 'DontDocMe'
+pub struct DocMe;
+struct DontDocMe;