Auto merge of rust-lang#84840 - Dylan-DPC:rollup-uzk7w0h, r=Dylan-DPC

Rollup of 6 pull requests

Successful merges:

 - rust-lang#84072 (Allow setting `target_family` to multiple values, and implement `target_family="wasm"`)
 - rust-lang#84744 (Add ErrorKind::OutOfMemory)
 - rust-lang#84784 (Add help message to suggest const for unused type param)
 - rust-lang#84811 (RustDoc: Fix bounds linking trait.Foo instead of traitalias.Foo)
 - rust-lang#84818 (suggestion for unit enum variant when matched with a patern)
 - rust-lang#84832 (Do not print visibility in external traits)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

compiler/rustc_resolve/src/late/diagnostics.rs

@@ -819,6 +819,19 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
             _ => false,
         };
 
+        let find_span = |source: &PathSource<'_>, err: &mut DiagnosticBuilder<'_>| {
+            match source {
+                PathSource::Expr(Some(Expr { span, kind: ExprKind::Call(_, _), .. }))
+                | PathSource::TupleStruct(span, _) => {
+                    // We want the main underline to cover the suggested code as well for
+                    // cleaner output.
+                    err.set_span(*span);
+                    *span
+                }
+                _ => span,
+            }
+        };
+
         let mut bad_struct_syntax_suggestion = |def_id: DefId| {
             let (followed_by_brace, closing_brace) = self.followed_by_brace(span);
 
@@ -862,18 +875,7 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
                     }
                 }
                 PathSource::Expr(_) | PathSource::TupleStruct(..) | PathSource::Pat => {
-                    let span = match &source {
-                        PathSource::Expr(Some(Expr {
-                            span, kind: ExprKind::Call(_, _), ..
-                        }))
-                        | PathSource::TupleStruct(span, _) => {
-                            // We want the main underline to cover the suggested code as well for
-                            // cleaner output.
-                            err.set_span(*span);
-                            *span
-                        }
-                        _ => span,
-                    };
+                    let span = find_span(&source, err);
                     if let Some(span) = self.def_span(def_id) {
                         err.span_label(span, &format!("`{}` defined here", path_str));
                     }
@@ -1047,6 +1049,23 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
             ) if ns == ValueNS => {
                 bad_struct_syntax_suggestion(def_id);
             }
+            (Res::Def(DefKind::Ctor(_, CtorKind::Const), def_id), _) if ns == ValueNS => {
+                match source {
+                    PathSource::Expr(_) | PathSource::TupleStruct(..) | PathSource::Pat => {
+                        let span = find_span(&source, err);
+                        if let Some(span) = self.def_span(def_id) {
+                            err.span_label(span, &format!("`{}` defined here", path_str));
+                        }
+                        err.span_suggestion(
+                            span,
+                            &format!("use this syntax instead"),
+                            format!("{path_str}"),
+                            Applicability::MaybeIncorrect,
+                        );
+                    }
+                    _ => return false,
+                }
+            }
             (Res::Def(DefKind::Ctor(_, CtorKind::Fn), def_id), _) if ns == ValueNS => {
                 if let Some(span) = self.def_span(def_id) {
                     err.span_label(span, &format!("`{}` defined here", path_str));

compiler/rustc_session/src/config.rs

@@ -816,7 +816,7 @@ fn default_configuration(sess: &Session) -> CrateConfig {
     ret.reserve(6); // the minimum number of insertions
     // Target bindings.
     ret.insert((sym::target_os, Some(Symbol::intern(os))));
-    if let Some(ref fam) = sess.target.os_family {
+    for fam in &sess.target.families {
         ret.insert((sym::target_family, Some(Symbol::intern(fam))));
         if fam == "windows" {
             ret.insert((sym::windows, None));

compiler/rustc_target/src/spec/apple_base.rs

@@ -23,7 +23,7 @@ pub fn opts(os: &str) -> TargetOptions {
         function_sections: false,
         dynamic_linking: true,
         executables: true,
-        os_family: Some("unix".to_string()),
+        families: vec!["unix".to_string()],
         is_like_osx: true,
         dwarf_version: Some(2),
         has_rpath: true,

compiler/rustc_target/src/spec/dragonfly_base.rs

@@ -5,7 +5,7 @@ pub fn opts() -> TargetOptions {
         os: "dragonfly".to_string(),
         dynamic_linking: true,
         executables: true,
-        os_family: Some("unix".to_string()),
+        families: vec!["unix".to_string()],
         linker_is_gnu: true,
         has_rpath: true,
         position_independent_executables: true,

compiler/rustc_target/src/spec/freebsd_base.rs

@@ -5,7 +5,7 @@ pub fn opts() -> TargetOptions {
         os: "freebsd".to_string(),
         dynamic_linking: true,
         executables: true,
-        os_family: Some("unix".to_string()),
+        families: vec!["unix".to_string()],
         linker_is_gnu: true,
         has_rpath: true,
         position_independent_executables: true,

compiler/rustc_target/src/spec/fuchsia_base.rs

@@ -25,7 +25,7 @@ pub fn opts() -> TargetOptions {
         linker: Some("rust-lld".to_owned()),
         dynamic_linking: true,
         executables: true,
-        os_family: Some("unix".to_string()),
+        families: vec!["unix".to_string()],
         is_like_fuchsia: true,
         linker_is_gnu: true,
         pre_link_args,

compiler/rustc_target/src/spec/haiku_base.rs

@@ -5,7 +5,7 @@ pub fn opts() -> TargetOptions {
         os: "haiku".to_string(),
         dynamic_linking: true,
         executables: true,
-        os_family: Some("unix".to_string()),
+        families: vec!["unix".to_string()],
         relro_level: RelroLevel::Full,
         linker_is_gnu: true,
         ..Default::default()

compiler/rustc_target/src/spec/illumos_base.rs

@@ -20,7 +20,7 @@ pub fn opts() -> TargetOptions {
         dynamic_linking: true,
         executables: true,
         has_rpath: true,
-        os_family: Some("unix".to_string()),
+        families: vec!["unix".to_string()],
         is_like_solaris: true,
         limit_rdylib_exports: false, // Linker doesn't support this
         eliminate_frame_pointer: false,

compiler/rustc_target/src/spec/l4re_base.rs

@@ -20,7 +20,7 @@ pub fn opts() -> TargetOptions {
         executables: true,
         panic_strategy: PanicStrategy::Abort,
         linker: Some("ld".to_string()),
-        os_family: Some("unix".to_string()),
+        families: vec!["unix".to_string()],
         ..Default::default()
     }
 }

compiler/rustc_target/src/spec/linux_base.rs

@@ -5,7 +5,7 @@ pub fn opts() -> TargetOptions {
         os: "linux".to_string(),
         dynamic_linking: true,
         executables: true,
-        os_family: Some("unix".to_string()),
+        families: vec!["unix".to_string()],
         linker_is_gnu: true,
         has_rpath: true,
         position_independent_executables: true,

compiler/rustc_target/src/spec/mod.rs

@@ -1042,8 +1042,12 @@ pub struct TargetOptions {
     pub staticlib_prefix: String,
     /// String to append to the name of every static library. Defaults to ".a".
     pub staticlib_suffix: String,
-    /// OS family to use for conditional compilation. Valid options: "unix", "windows".
-    pub os_family: Option<String>,
+    /// Values of the `target_family` cfg set for this target.
+    ///
+    /// Common options are: "unix", "windows". Defaults to no families.
+    ///
+    /// See <https://doc.rust-lang.org/reference/conditional-compilation.html#target_family>.
+    pub families: Vec<String>,
     /// Whether the target toolchain's ABI supports returning small structs as an integer.
     pub abi_return_struct_as_int: bool,
     /// Whether the target toolchain is like macOS's. Only useful for compiling against iOS/macOS,
@@ -1293,7 +1297,7 @@ impl Default for TargetOptions {
             exe_suffix: String::new(),
             staticlib_prefix: "lib".to_string(),
             staticlib_suffix: ".a".to_string(),
-            os_family: None,
+            families: Vec::new(),
             abi_return_struct_as_int: false,
             is_like_osx: false,
             is_like_solaris: false,
@@ -1605,14 +1609,6 @@ impl Target {
                         .map(|s| s.to_string() );
                 }
             } );
-            ($key_name:ident = $json_name:expr, optional) => ( {
-                let name = $json_name;
-                if let Some(o) = obj.find(name) {
-                    base.$key_name = o
-                        .as_string()
-                        .map(|s| s.to_string() );
-                }
-            } );
             ($key_name:ident, LldFlavor) => ( {
                 let name = (stringify!($key_name)).replace("_", "-");
                 obj.find(&name[..]).and_then(|o| o.as_string().and_then(|s| {
@@ -1759,6 +1755,16 @@ impl Target {
                     Some(Ok(()))
                 })).unwrap_or(Ok(()))
             } );
+            ($key_name:ident, TargetFamilies) => ( {
+                let value = obj.find("target-family");
+                if let Some(v) = value.and_then(Json::as_array) {
+                    base.$key_name = v.iter()
+                        .map(|a| a.as_string().unwrap().to_string())
+                        .collect();
+                } else if let Some(v) = value.and_then(Json::as_string) {
+                    base.$key_name = vec![v.to_string()];
+                }
+            } );
         }
 
         if let Some(s) = obj.find("target-endian").and_then(Json::as_string) {
@@ -1802,7 +1808,7 @@ impl Target {
         key!(exe_suffix);
         key!(staticlib_prefix);
         key!(staticlib_suffix);
-        key!(os_family = "target-family", optional);
+        key!(families, TargetFamilies);
         key!(abi_return_struct_as_int, bool);
         key!(is_like_osx, bool);
         key!(is_like_solaris, bool);
@@ -2042,7 +2048,7 @@ impl ToJson for Target {
         target_option_val!(exe_suffix);
         target_option_val!(staticlib_prefix);
         target_option_val!(staticlib_suffix);
-        target_option_val!(os_family, "target-family");
+        target_option_val!(families, "target-family");
         target_option_val!(abi_return_struct_as_int);
         target_option_val!(is_like_osx);
         target_option_val!(is_like_solaris);

compiler/rustc_target/src/spec/netbsd_base.rs

@@ -5,7 +5,7 @@ pub fn opts() -> TargetOptions {
         os: "netbsd".to_string(),
         dynamic_linking: true,
         executables: true,
-        os_family: Some("unix".to_string()),
+        families: vec!["unix".to_string()],
         linker_is_gnu: true,
         no_default_libraries: false,
         has_rpath: true,

compiler/rustc_target/src/spec/openbsd_base.rs

@@ -5,7 +5,7 @@ pub fn opts() -> TargetOptions {
         os: "openbsd".to_string(),
         dynamic_linking: true,
         executables: true,
-        os_family: Some("unix".to_string()),
+        families: vec!["unix".to_string()],
         linker_is_gnu: true,
         has_rpath: true,
         abi_return_struct_as_int: true,

compiler/rustc_target/src/spec/redox_base.rs

@@ -6,7 +6,7 @@ pub fn opts() -> TargetOptions {
         env: "relibc".to_string(),
         dynamic_linking: true,
         executables: true,
-        os_family: Some("unix".to_string()),
+        families: vec!["unix".to_string()],
         linker_is_gnu: true,
         has_rpath: true,
         position_independent_executables: true,

compiler/rustc_target/src/spec/solaris_base.rs

@@ -6,7 +6,7 @@ pub fn opts() -> TargetOptions {
         dynamic_linking: true,
         executables: true,
         has_rpath: true,
-        os_family: Some("unix".to_string()),
+        families: vec!["unix".to_string()],
         is_like_solaris: true,
         limit_rdylib_exports: false, // Linker doesn't support this
         eh_frame_header: false,

compiler/rustc_target/src/spec/vxworks_base.rs

@@ -9,7 +9,7 @@ pub fn opts() -> TargetOptions {
         exe_suffix: ".vxe".to_string(),
         dynamic_linking: true,
         executables: true,
-        os_family: Some("unix".to_string()),
+        families: vec!["unix".to_string()],
         linker_is_gnu: true,
         has_rpath: true,
         has_elf_tls: true,

compiler/rustc_target/src/spec/wasm32_unknown_emscripten.rs

@@ -38,7 +38,7 @@ pub fn target() -> Target {
         is_like_emscripten: true,
         panic_strategy: PanicStrategy::Unwind,
         post_link_args,
-        os_family: Some("unix".to_string()),
+        families: vec!["unix".to_string()],
         ..options
     };
     Target {

compiler/rustc_target/src/spec/wasm_base.rs

@@ -61,6 +61,7 @@ pub fn options() -> TargetOptions {
 
     TargetOptions {
         is_like_wasm: true,
+        families: vec!["wasm".to_string()],
 
         // we allow dynamic linking, but only cdylibs. Basically we allow a
         // final library artifact that exports some symbols (a wasm module) but

compiler/rustc_target/src/spec/windows_gnu_base.rs

@@ -71,7 +71,7 @@ pub fn opts() -> TargetOptions {
         dll_prefix: String::new(),
         dll_suffix: ".dll".to_string(),
         exe_suffix: ".exe".to_string(),
-        os_family: Some("windows".to_string()),
+        families: vec!["windows".to_string()],
         is_like_windows: true,
         allows_weak_linkage: false,
         pre_link_args,

compiler/rustc_target/src/spec/windows_msvc_base.rs

@@ -13,7 +13,7 @@ pub fn opts() -> TargetOptions {
         exe_suffix: ".exe".to_string(),
         staticlib_prefix: String::new(),
         staticlib_suffix: ".lib".to_string(),
-        os_family: Some("windows".to_string()),
+        families: vec!["windows".to_string()],
         crt_static_allows_dylibs: true,
         crt_static_respected: true,
         requires_uwtable: true,

compiler/rustc_typeck/src/check/wfcheck.rs

@@ -1298,12 +1298,14 @@ fn check_variances_for_type_defn<'tcx>(
 
         match param.name {
             hir::ParamName::Error => {}
-            _ => report_bivariance(tcx, param.span, param.name.ident().name),
+            _ => report_bivariance(tcx, param),
         }
     }
 }
 
-fn report_bivariance(tcx: TyCtxt<'_>, span: Span, param_name: Symbol) {
+fn report_bivariance(tcx: TyCtxt<'_>, param: &rustc_hir::GenericParam<'_>) {
+    let span = param.span;
+    let param_name = param.name.ident().name;
     let mut err = error_392(tcx, span, param_name);
 
     let suggested_marker_id = tcx.lang_items().phantom_data();
@@ -1318,7 +1320,14 @@ fn report_bivariance(tcx: TyCtxt<'_>, span: Span, param_name: Symbol) {
         format!("consider removing `{}` or referring to it in a field", param_name)
     };
     err.help(&msg);
-    err.emit();
+
+    if matches!(param.kind, rustc_hir::GenericParamKind::Type { .. }) {
+        err.help(&format!(
+            "if you intended `{0}` to be a const parameter, use `const {0}: usize` instead",
+            param_name
+        ));
+    }
+    err.emit()
 }
 
 /// Feature gates RFC 2056 -- trivial bounds, checking for global bounds that

library/std/src/io/error.rs

@@ -186,6 +186,11 @@ pub enum ErrorKind {
     /// This means that the operation can never succeed.
     #[stable(feature = "unsupported_error", since = "1.53.0")]
     Unsupported,
+
+    /// An operation could not be completed, because it failed
+    /// to allocate enough memory.
+    #[stable(feature = "out_of_memory_error", since = "1.53.0")]
+    OutOfMemory,
 }
 
 impl ErrorKind {
@@ -210,6 +215,7 @@ impl ErrorKind {
             ErrorKind::Other => "other os error",
             ErrorKind::UnexpectedEof => "unexpected end of file",
             ErrorKind::Unsupported => "unsupported",
+            ErrorKind::OutOfMemory => "out of memory",
         }
     }
 }

library/std/src/sys/unix/mod.rs

@@ -149,6 +149,7 @@ pub fn decode_error_kind(errno: i32) -> ErrorKind {
         libc::ETIMEDOUT => ErrorKind::TimedOut,
         libc::EEXIST => ErrorKind::AlreadyExists,
         libc::ENOSYS => ErrorKind::Unsupported,
+        libc::ENOMEM => ErrorKind::OutOfMemory,
 
         // These two constants can have the same value on some systems,
         // but different values on others, so we can't use a match

library/std/src/sys/wasi/mod.rs

@@ -77,6 +77,7 @@ pub fn decode_error_kind(errno: i32) -> std_io::ErrorKind {
         wasi::ERRNO_EXIST => AlreadyExists,
         wasi::ERRNO_AGAIN => WouldBlock,
         wasi::ERRNO_NOSYS => Unsupported,
+        wasi::ERRNO_NOMEM => OutOfMemory,
         _ => Other,
     }
 }

library/std/src/sys/windows/c.rs

@@ -168,6 +168,8 @@ pub const ERROR_FILE_NOT_FOUND: DWORD = 2;
 pub const ERROR_PATH_NOT_FOUND: DWORD = 3;
 pub const ERROR_ACCESS_DENIED: DWORD = 5;
 pub const ERROR_INVALID_HANDLE: DWORD = 6;
+pub const ERROR_NOT_ENOUGH_MEMORY: DWORD = 8;
+pub const ERROR_OUTOFMEMORY: DWORD = 14;
 pub const ERROR_NO_MORE_FILES: DWORD = 18;
 pub const ERROR_HANDLE_EOF: DWORD = 38;
 pub const ERROR_FILE_EXISTS: DWORD = 80;

library/std/src/sys/windows/mod.rs

@@ -71,6 +71,7 @@ pub fn decode_error_kind(errno: i32) -> ErrorKind {
         c::ERROR_PATH_NOT_FOUND => return ErrorKind::NotFound,
         c::ERROR_NO_DATA => return ErrorKind::BrokenPipe,
         c::ERROR_INVALID_PARAMETER => return ErrorKind::InvalidInput,
+        c::ERROR_NOT_ENOUGH_MEMORY | c::ERROR_OUTOFMEMORY => return ErrorKind::OutOfMemory,
         c::ERROR_SEM_TIMEOUT
         | c::WAIT_TIMEOUT
         | c::ERROR_DRIVER_CANCEL_TIMEOUT