Auto merge of #124993 - jieyouxu:rollup-u02aso7, r=jieyouxu

Rollup of 5 pull requests

Successful merges:

 - #124233 (Add `-lmingwex` second time in `mingw_libs`)
 - #124318 (ignore generics args in attribute paths)
 - #124899 (bootstrap: add comments for the automatic dry run)
 - #124904 (reachable computation: extend explanation of what this does, and why)
 - #124930 (Make sure we consume a generic arg when checking mistyped turbofish)

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

compiler/rustc_parse/src/parser/diagnostics.rs

@@ -1223,7 +1223,11 @@ impl<'a> Parser<'a> {
             let x = self.parse_seq_to_before_end(
                 &token::Gt,
                 SeqSep::trailing_allowed(token::Comma),
-                |p| p.parse_generic_arg(None),
+                |p| match p.parse_generic_arg(None)? {
+                    Some(arg) => Ok(arg),
+                    // If we didn't eat a generic arg, then we should error.
+                    None => p.unexpected_any(),
+                },
             );
             match x {
                 Ok((_, _, Recovered::No)) => {

compiler/rustc_parse/src/parser/path.rs

@@ -160,7 +160,7 @@ impl<'a> Parser<'a> {
         style: PathStyle,
         ty_generics: Option<&Generics>,
     ) -> PResult<'a, Path> {
-        let reject_generics_if_mod_style = |parser: &Parser<'_>, path: &Path| {
+        let reject_generics_if_mod_style = |parser: &Parser<'_>, path: Path| {
             // Ensure generic arguments don't end up in attribute paths, such as:
             //
             //     macro_rules! m {
@@ -178,21 +178,26 @@ impl<'a> Parser<'a> {
                     .map(|arg| arg.span())
                     .collect::<Vec<_>>();
                 parser.dcx().emit_err(errors::GenericsInPath { span });
+                // Ignore these arguments to prevent unexpected behaviors.
+                let segments = path
+                    .segments
+                    .iter()
+                    .map(|segment| PathSegment { ident: segment.ident, id: segment.id, args: None })
+                    .collect();
+                Path { segments, ..path }
+            } else {
+                path
             }
         };
 
-        maybe_whole!(self, NtPath, |path| {
-            reject_generics_if_mod_style(self, &path);
-            path.into_inner()
-        });
+        maybe_whole!(self, NtPath, |path| reject_generics_if_mod_style(self, path.into_inner()));
 
         if let token::Interpolated(nt) = &self.token.kind {
             if let token::NtTy(ty) = &nt.0 {
                 if let ast::TyKind::Path(None, path) = &ty.kind {
                     let path = path.clone();
                     self.bump();
-                    reject_generics_if_mod_style(self, &path);
-                    return Ok(path);
+                    return Ok(reject_generics_if_mod_style(self, path));
                 }
             }
         }

compiler/rustc_passes/src/reachable.rs

@@ -1,14 +1,26 @@
-//! Finds local items that are externally reachable, which means that other crates need access to
-//! their compiled machine code or their MIR.
+//! Finds local items that are "reachable", which means that other crates need access to their
+//! compiled code or their *runtime* MIR. (Compile-time MIR is always encoded anyway, so we don't
+//! worry about that here.)
 //!
-//! An item is "externally reachable" if it is relevant for other crates. This obviously includes
-//! all public items. However, some of these items cannot be compiled to machine code (because they
-//! are generic), and for some the machine code is not sufficient (because we want to cross-crate
-//! inline them). These items "need cross-crate MIR". When a reachable function `f` needs
-//! cross-crate MIR, then all the functions it calls also become reachable, as they will be
-//! necessary to use the MIR of `f` from another crate. Furthermore, an item can become "externally
-//! reachable" by having a `const`/`const fn` return a pointer to that item, so we also need to
-//! recurse into reachable `const`/`const fn`.
+//! An item is "reachable" if codegen that happens in downstream crates can end up referencing this
+//! item. This obviously includes all public items. However, some of these items cannot be codegen'd
+//! (because they are generic), and for some the compiled code is not sufficient (because we want to
+//! cross-crate inline them). These items "need cross-crate MIR". When a reachable function `f`
+//! needs cross-crate MIR, then its MIR may be codegen'd in a downstream crate, and hence items it
+//! mentions need to be considered reachable.
+//!
+//! Furthermore, if a `const`/`const fn` is reachable, then it can return pointers to other items,
+//! making those reachable as well. For instance, consider a `const fn` returning a pointer to an
+//! otherwise entirely private function: if a downstream crate calls that `const fn` to compute the
+//! initial value of a `static`, then it needs to generate a direct reference to this function --
+//! i.e., the function is directly reachable from that downstream crate! Hence we have to recurse
+//! into `const` and `const fn`.
+//!
+//! Conversely, reachability *stops* when it hits a monomorphic non-`const` function that we do not
+//! want to cross-crate inline. That function will just be codegen'd in this crate, which means the
+//! monomorphization collector will consider it a root and then do another graph traversal to
+//! codegen everything called by this function -- but that's a very different graph from what we are
+//! considering here as at that point, everything is monomorphic.
 
 use hir::def_id::LocalDefIdSet;
 use rustc_data_structures::stack::ensure_sufficient_stack;

compiler/rustc_target/src/spec/base/windows_gnu.rs

@@ -40,6 +40,9 @@ pub fn opts() -> TargetOptions {
         //
         // See https://github.com/rust-lang/rust/pull/47483 for some more details.
         "-lmsvcrt",
+        // Math functions missing in MSVCRT (they are present in UCRT) require
+        // this dependency cycle: `libmingwex.a` -> `libmsvcrt.a` -> `libmingwex.a`.
+        "-lmingwex",
         "-luser32",
         "-lkernel32",
     ];