Auto merge of #98075 - JohnTitor:rollup-nqwodnk, r=JohnTitor

Rollup of 4 pull requests

Successful merges:

 - #95211 (Improve parser diagnostics)
 - #95243 (Add Apple WatchOS compile targets)
 - #97385 (Add WIP stable MIR crate)
 - #97508 (Harden bad placeholder checks on statics/consts)

Failed merges:

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

Author: bors

Cargo.lock

@@ -3440,6 +3440,7 @@ dependencies = [
  "jemalloc-sys",
  "rustc_codegen_ssa",
  "rustc_driver",
+ "rustc_smir",
 ]
 
 [[package]]
@@ -4437,6 +4438,21 @@ dependencies = [
  "tracing",
 ]
 
+[[package]]
+name = "rustc_smir"
+version = "0.0.0"
+dependencies = [
+ "rustc_borrowck",
+ "rustc_driver",
+ "rustc_hir",
+ "rustc_interface",
+ "rustc_middle",
+ "rustc_mir_dataflow",
+ "rustc_mir_transform",
+ "rustc_serialize",
+ "rustc_trait_selection",
+]
+
 [[package]]
 name = "rustc_span"
 version = "0.0.0"

compiler/rustc/Cargo.toml

@@ -9,6 +9,9 @@ rustc_driver = { path = "../rustc_driver" }
 # Make sure rustc_codegen_ssa ends up in the sysroot, because this
 # crate is intended to be used by codegen backends, which may not be in-tree.
 rustc_codegen_ssa = { path = "../rustc_codegen_ssa" }
+# Make sure rustc_smir ends up in the sysroot, because this
+# crate is intended to be used by stable MIR consumers, which are not in-tree
+rustc_smir = { path = "../rustc_smir" }
 
 [dependencies.jemalloc-sys]
 version = "0.5.0"

compiler/rustc_codegen_llvm/src/back/write.rs

@@ -1036,7 +1036,8 @@ unsafe fn embed_bitcode(
     // reason (see issue #90326 for historical background).
     let is_apple = cgcx.opts.target_triple.triple().contains("-ios")
         || cgcx.opts.target_triple.triple().contains("-darwin")
-        || cgcx.opts.target_triple.triple().contains("-tvos");
+        || cgcx.opts.target_triple.triple().contains("-tvos")
+        || cgcx.opts.target_triple.triple().contains("-watchos");
     if is_apple
         || cgcx.opts.target_triple.triple().starts_with("wasm")
         || cgcx.opts.target_triple.triple().starts_with("asmjs")

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -2606,7 +2606,7 @@ fn add_apple_sdk(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) {
     let os = &sess.target.os;
     let llvm_target = &sess.target.llvm_target;
     if sess.target.vendor != "apple"
-        || !matches!(os.as_ref(), "ios" | "tvos")
+        || !matches!(os.as_ref(), "ios" | "tvos" | "watchos")
         || flavor != LinkerFlavor::Gcc
     {
         return;
@@ -2616,11 +2616,16 @@ fn add_apple_sdk(cmd: &mut dyn Linker, sess: &Session, flavor: LinkerFlavor) {
         ("x86_64", "tvos") => "appletvsimulator",
         ("arm", "ios") => "iphoneos",
         ("aarch64", "ios") if llvm_target.contains("macabi") => "macosx",
-        ("aarch64", "ios") if llvm_target.contains("sim") => "iphonesimulator",
+        ("aarch64", "ios") if llvm_target.ends_with("-simulator") => "iphonesimulator",
         ("aarch64", "ios") => "iphoneos",
         ("x86", "ios") => "iphonesimulator",
         ("x86_64", "ios") if llvm_target.contains("macabi") => "macosx",
         ("x86_64", "ios") => "iphonesimulator",
+        ("x86_64", "watchos") => "watchsimulator",
+        ("arm64_32", "watchos") => "watchos",
+        ("aarch64", "watchos") if llvm_target.ends_with("-simulator") => "watchsimulator",
+        ("aarch64", "watchos") => "watchos",
+        ("arm", "watchos") => "watchos",
         _ => {
             sess.err(&format!("unsupported arch `{}` for os `{}`", arch, os));
             return;
@@ -2667,6 +2672,11 @@ fn get_apple_sdk_root(sdk_name: &str) -> Result<String, String> {
             "macosx10.15"
                 if sdkroot.contains("iPhoneOS.platform")
                     || sdkroot.contains("iPhoneSimulator.platform") => {}
+            "watchos"
+                if sdkroot.contains("WatchSimulator.platform")
+                    || sdkroot.contains("MacOSX.platform") => {}
+            "watchsimulator"
+                if sdkroot.contains("WatchOS.platform") || sdkroot.contains("MacOSX.platform") => {}
             // Ignore `SDKROOT` if it's not a valid path.
             _ if !p.is_absolute() || p == Path::new("/") || !p.exists() => {}
             _ => return Ok(sdkroot),

compiler/rustc_parse/src/parser/diagnostics.rs

@@ -28,6 +28,7 @@ use std::ops::{Deref, DerefMut};
 
 use std::mem::take;
 
+use crate::parser;
 use tracing::{debug, trace};
 
 const TURBOFISH_SUGGESTION_STR: &str =
@@ -481,6 +482,35 @@ impl<'a> Parser<'a> {
             .map(|x| TokenType::Token(x.clone()))
             .chain(inedible.iter().map(|x| TokenType::Token(x.clone())))
             .chain(self.expected_tokens.iter().cloned())
+            .filter_map(|token| {
+                // filter out suggestions which suggest the same token which was found and deemed incorrect
+                fn is_ident_eq_keyword(found: &TokenKind, expected: &TokenType) -> bool {
+                    if let TokenKind::Ident(current_sym, _) = found {
+                        if let TokenType::Keyword(suggested_sym) = expected {
+                            return current_sym == suggested_sym;
+                        }
+                    }
+                    false
+                }
+                if token != parser::TokenType::Token(self.token.kind.clone()) {
+                    let eq = is_ident_eq_keyword(&self.token.kind, &token);
+                    // if the suggestion is a keyword and the found token is an ident,
+                    // the content of which are equal to the suggestion's content,
+                    // we can remove that suggestion (see the return None statement below)
+
+                    // if this isn't the case however, and the suggestion is a token the
+                    // content of which is the same as the found token's, we remove it as well
+                    if !eq {
+                        if let TokenType::Token(kind) = &token {
+                            if kind == &self.token.kind {
+                                return None;
+                            }
+                        }
+                        return Some(token);
+                    }
+                }
+                return None;
+            })
             .collect::<Vec<_>>();
         expected.sort_by_cached_key(|x| x.to_string());
         expected.dedup();

compiler/rustc_parse/src/parser/expr.rs

@@ -980,12 +980,26 @@ impl<'a> Parser<'a> {
 
     fn parse_dot_or_call_expr_with_(&mut self, mut e: P<Expr>, lo: Span) -> PResult<'a, P<Expr>> {
         loop {
-            if self.eat(&token::Question) {
+            let has_question = if self.prev_token.kind == TokenKind::Ident(kw::Return, false) {
+                // we are using noexpect here because we don't expect a `?` directly after a `return`
+                // which could be suggested otherwise
+                self.eat_noexpect(&token::Question)
+            } else {
+                self.eat(&token::Question)
+            };
+            if has_question {
                 // `expr?`
                 e = self.mk_expr(lo.to(self.prev_token.span), ExprKind::Try(e), AttrVec::new());
                 continue;
             }
-            if self.eat(&token::Dot) {
+            let has_dot = if self.prev_token.kind == TokenKind::Ident(kw::Return, false) {
+                // we are using noexpect here because we don't expect a `.` directly after a `return`
+                // which could be suggested otherwise
+                self.eat_noexpect(&token::Dot)
+            } else {
+                self.eat(&token::Dot)
+            };
+            if has_dot {
                 // expr.f
                 e = self.parse_dot_suffix_expr(lo, e)?;
                 continue;
@@ -1541,9 +1555,13 @@ impl<'a> Parser<'a> {
             self.parse_for_expr(label, lo, attrs)
         } else if self.eat_keyword(kw::Loop) {
             self.parse_loop_expr(label, lo, attrs)
-        } else if self.check(&token::OpenDelim(Delimiter::Brace)) || self.token.is_whole_block() {
+        } else if self.check_noexpect(&token::OpenDelim(Delimiter::Brace))
+            || self.token.is_whole_block()
+        {
             self.parse_block_expr(label, lo, BlockCheckMode::Default, attrs)
-        } else if !ate_colon && (self.check(&TokenKind::Comma) || self.check(&TokenKind::Gt)) {
+        } else if !ate_colon
+            && (self.check_noexpect(&TokenKind::Comma) || self.check_noexpect(&TokenKind::Gt))
+        {
             // We're probably inside of a `Path<'a>` that needs a turbofish
             let msg = "expected `while`, `for`, `loop` or `{` after a label";
             self.struct_span_err(self.token.span, msg).span_label(self.token.span, msg).emit();

compiler/rustc_parse/src/parser/mod.rs

@@ -547,6 +547,22 @@ impl<'a> Parser<'a> {
         is_present
     }
 
+    fn check_noexpect(&self, tok: &TokenKind) -> bool {
+        self.token == *tok
+    }
+
+    /// Consumes a token 'tok' if it exists. Returns whether the given token was present.
+    ///
+    /// the main purpose of this function is to reduce the cluttering of the suggestions list
+    /// which using the normal eat method could introduce in some cases.
+    pub fn eat_noexpect(&mut self, tok: &TokenKind) -> bool {
+        let is_present = self.check_noexpect(tok);
+        if is_present {
+            self.bump()
+        }
+        is_present
+    }
+
     /// Consumes a token 'tok' if it exists. Returns whether the given token was present.
     pub fn eat(&mut self, tok: &TokenKind) -> bool {
         let is_present = self.check(tok);

compiler/rustc_parse/src/parser/path.rs

@@ -2,7 +2,7 @@ use super::ty::{AllowPlus, RecoverQPath, RecoverReturnSign};
 use super::{Parser, Restrictions, TokenType};
 use crate::maybe_whole;
 use rustc_ast::ptr::P;
-use rustc_ast::token::{self, Delimiter, Token};
+use rustc_ast::token::{self, Delimiter, Token, TokenKind};
 use rustc_ast::{
     self as ast, AngleBracketedArg, AngleBracketedArgs, AnonConst, AssocConstraint,
     AssocConstraintKind, BlockCheckMode, GenericArg, GenericArgs, Generics, ParenthesizedArgs,
@@ -96,7 +96,7 @@ impl<'a> Parser<'a> {
     ///                ^ help: use double colon
     /// ```
     fn recover_colon_before_qpath_proj(&mut self) -> bool {
-        if self.token.kind != token::Colon
+        if !self.check_noexpect(&TokenKind::Colon)
             || self.look_ahead(1, |t| !t.is_ident() || t.is_reserved_ident())
         {
             return false;
@@ -478,7 +478,7 @@ impl<'a> Parser<'a> {
         while let Some(arg) = self.parse_angle_arg(ty_generics)? {
             args.push(arg);
             if !self.eat(&token::Comma) {
-                if self.token.kind == token::Semi
+                if self.check_noexpect(&TokenKind::Semi)
                     && self.look_ahead(1, |t| t.is_ident() || t.is_lifetime())
                 {
                     // Add `>` to the list of expected tokens.
@@ -517,7 +517,11 @@ impl<'a> Parser<'a> {
         let arg = self.parse_generic_arg(ty_generics)?;
         match arg {
             Some(arg) => {
-                if self.check(&token::Colon) | self.check(&token::Eq) {
+                // we are using noexpect here because we first want to find out if either `=` or `:`
+                // is present and then use that info to push the other token onto the tokens list
+                let separated =
+                    self.check_noexpect(&token::Colon) || self.check_noexpect(&token::Eq);
+                if separated && (self.check(&token::Colon) | self.check(&token::Eq)) {
                     let arg_span = arg.span();
                     let (binder, ident, gen_args) = match self.get_ident_from_generic_arg(&arg) {
                         Ok(ident_gen_args) => ident_gen_args,
@@ -553,6 +557,14 @@ impl<'a> Parser<'a> {
                         AssocConstraint { id: ast::DUMMY_NODE_ID, ident, gen_args, kind, span };
                     Ok(Some(AngleBracketedArg::Constraint(constraint)))
                 } else {
+                    // we only want to suggest `:` and `=` in contexts where the previous token
+                    // is an ident and the current token or the next token is an ident
+                    if self.prev_token.is_ident()
+                        && (self.token.is_ident() || self.look_ahead(1, |token| token.is_ident()))
+                    {
+                        self.check(&token::Colon);
+                        self.check(&token::Eq);
+                    }
                     Ok(Some(AngleBracketedArg::Arg(arg)))
                 }
             }

compiler/rustc_parse/src/parser/stmt.rs

@@ -260,7 +260,10 @@ impl<'a> Parser<'a> {
                     if let Ok(snip) = self.span_to_snippet(pat.span) {
                         err.span_label(pat.span, format!("while parsing the type for `{}`", snip));
                     }
-                    let err = if self.check(&token::Eq) {
+                    // we use noexpect here because we don't actually expect Eq to be here
+                    // but we are still checking for it in order to be able to handle it if
+                    // it is there
+                    let err = if self.check_noexpect(&token::Eq) {
                         err.emit();
                         None
                     } else {

compiler/rustc_smir/.gitignore

@@ -0,0 +1 @@
+target

compiler/rustc_smir/Cargo.toml

@@ -0,0 +1,28 @@
+[package]
+name = "rustc_smir"
+version = "0.0.0"
+edition = "2021"
+
+[dependencies]
+rustc_borrowck = { path = "../rustc_borrowck", optional = true }
+rustc_driver = { path = "../rustc_driver", optional = true }
+rustc_hir = { path = "../rustc_hir", optional = true }
+rustc_interface = { path = "../rustc_interface", optional = true }
+rustc_middle = { path = "../rustc_middle", optional = true }
+rustc_mir_dataflow = { path = "../rustc_mir_dataflow", optional = true }
+rustc_mir_transform = { path = "../rustc_mir_transform", optional = true }
+rustc_serialize = { path = "../rustc_serialize", optional = true }
+rustc_trait_selection = { path = "../rustc_trait_selection", optional = true }
+
+[features]
+default = [
+    "rustc_borrowck",
+    "rustc_driver",
+    "rustc_hir",
+    "rustc_interface",
+    "rustc_middle",
+    "rustc_mir_dataflow",
+    "rustc_mir_transform",
+    "rustc_serialize",
+    "rustc_trait_selection",
+]

compiler/rustc_smir/README.md

@@ -0,0 +1,75 @@
+This crate is regularly synced with its mirror in the rustc repo at `compiler/rustc_smir`.
+
+We use `git subtree` for this to preserve commits and allow the rustc repo to
+edit these crates without having to touch this repo. This keeps the crates compiling
+while allowing us to independently work on them here. The effort of keeping them in
+sync is pushed entirely onto us, without affecting rustc workflows negatively.
+This may change in the future, but changes to policy should only be done via a
+compiler team MCP.
+
+## Instructions for working on this crate locally
+
+Since the crate is the same in the rustc repo and here, the dependencies on rustc_* crates
+will only either work here or there, but never in both places at the same time. Thus we use
+optional dependencies on the rustc_* crates, requiring local development to use
+
+```
+cargo build --no-default-features -Zavoid-dev-deps
+```
+
+in order to compile successfully.
+
+## Instructions for syncing
+
+### Updating this repository
+
+In the rustc repo, execute
+
+```
+git subtree push --prefix=compiler/rustc_smir url_to_your_fork_of_project_stable_mir some_feature_branch
+```
+
+and then open a PR of your `some_feature_branch` against https://github.com/rust-lang/project-stable-mir
+
+### Updating the rustc library
+
+First we need to bump our stack limit, as the rustc repo otherwise quickly hits that:
+
+```
+ulimit -s 60000
+```
+
+#### Maximum function recursion depth (1000) reached
+
+Then we need to disable `dash` as the default shell for sh scripts, as otherwise we run into a
+hard limit of a recursion depth of 1000:
+
+```
+sudo dpkg-reconfigure dash
+```
+
+and then select `No` to disable dash.
+
+
+#### Patching your `git worktree`
+
+The regular git worktree does not scale to repos of the size of the rustc repo.
+So download the `git-subtree.sh` from https://github.com/gitgitgadget/git/pull/493/files and run
+
+```
+sudo cp --backup /path/to/patched/git-subtree.sh /usr/lib/git-core/git-subtree
+sudo chmod --reference=/usr/lib/git-core/git-subtree~ /usr/lib/git-core/git-subtree
+sudo chown --reference=/usr/lib/git-core/git-subtree~ /usr/lib/git-core/git-subtree
+```
+
+#### Actually doing a sync
+
+In the rustc repo, execute
+
+```
+git subtree pull --prefix=compiler/rustc_smir https://github.com/rust-lang/project-stable-mir smir
+```
+
+Note: only ever sync to rustc from the project-stable-mir's `smir` branch. Do not sync with your own forks.
+
+Then open a PR against rustc just like a regular PR.

compiler/rustc_smir/rust-toolchain.toml

@@ -0,0 +1,3 @@
+[toolchain]
+channel = "nightly-2022-06-01"
+components = [ "rustfmt", "rustc-dev" ]

compiler/rustc_smir/src/lib.rs

@@ -0,0 +1,17 @@
+//! The WIP stable interface to rustc internals.
+//!
+//! For more information see https://github.com/rust-lang/project-stable-mir
+//!
+//! # Note
+//!
+//! This API is still completely unstable and subject to change.
+
+#![doc(
+    html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/",
+    test(attr(allow(unused_variables), deny(warnings)))
+)]
+#![cfg_attr(not(feature = "default"), feature(rustc_private))]
+
+pub mod mir;
+
+pub mod very_unstable;