Auto merge of #120586 - ShE3py:exprkind-err, r=fmease

Add `ErrorGuaranteed` to `ast::ExprKind::Err`

See #119967 for context
```
      \
       \
          _~^~^~_
      \) /  o o  \ (/
        '_   -   _'
        / '-----' \
```

r? fmease

compiler/rustc_ast/src/ast.rs

@@ -1296,23 +1296,10 @@ impl Expr {
             ExprKind::Yeet(..) => ExprPrecedence::Yeet,
             ExprKind::FormatArgs(..) => ExprPrecedence::FormatArgs,
             ExprKind::Become(..) => ExprPrecedence::Become,
-            ExprKind::Err => ExprPrecedence::Err,
+            ExprKind::Err(_) | ExprKind::Dummy => ExprPrecedence::Err,
         }
     }
 
-    pub fn take(&mut self) -> Self {
-        mem::replace(
-            self,
-            Expr {
-                id: DUMMY_NODE_ID,
-                kind: ExprKind::Err,
-                span: DUMMY_SP,
-                attrs: AttrVec::new(),
-                tokens: None,
-            },
-        )
-    }
-
     /// To a first-order approximation, is this a pattern?
     pub fn is_approximately_pattern(&self) -> bool {
         matches!(
@@ -1531,7 +1518,10 @@ pub enum ExprKind {
     FormatArgs(P<FormatArgs>),
 
     /// Placeholder for an expression that wasn't syntactically well formed in some way.
-    Err,
+    Err(ErrorGuaranteed),
+
+    /// Acts as a null expression. Lowering it will always emit a bug.
+    Dummy,
 }
 
 /// Used to differentiate between `for` loops and `for await` loops.

compiler/rustc_ast/src/mut_visit.rs

@@ -1526,7 +1526,7 @@ pub fn noop_visit_expr<T: MutVisitor>(
         }
         ExprKind::Try(expr) => vis.visit_expr(expr),
         ExprKind::TryBlock(body) => vis.visit_block(body),
-        ExprKind::Lit(_) | ExprKind::IncludedBytes(..) | ExprKind::Err => {}
+        ExprKind::Lit(_) | ExprKind::IncludedBytes(..) | ExprKind::Err(_) | ExprKind::Dummy => {}
     }
     vis.visit_id(id);
     vis.visit_span(span);
@@ -1642,7 +1642,7 @@ impl DummyAstNode for Expr {
     fn dummy() -> Self {
         Expr {
             id: DUMMY_NODE_ID,
-            kind: ExprKind::Err,
+            kind: ExprKind::Dummy,
             span: Default::default(),
             attrs: Default::default(),
             tokens: Default::default(),

compiler/rustc_ast/src/util/classify.rs

@@ -89,7 +89,8 @@ pub fn expr_trailing_brace(mut expr: &ast::Expr) -> Option<&ast::Expr> {
             | Paren(_)
             | Try(_)
             | Yeet(None)
-            | Err => break None,
+            | Err(_)
+            | Dummy => break None,
         }
     }
 }

compiler/rustc_ast/src/visit.rs

@@ -1063,7 +1063,7 @@ pub fn walk_expr<'a, V: Visitor<'a>>(visitor: &mut V, expression: &'a Expr) -> V
         }
         ExprKind::Try(subexpression) => try_visit!(visitor.visit_expr(subexpression)),
         ExprKind::TryBlock(body) => try_visit!(visitor.visit_block(body)),
-        ExprKind::Lit(_) | ExprKind::IncludedBytes(..) | ExprKind::Err => {}
+        ExprKind::Lit(_) | ExprKind::IncludedBytes(..) | ExprKind::Err(_) | ExprKind::Dummy => {}
     }
 
     visitor.visit_expr_post(expression)

compiler/rustc_ast_lowering/src/expr.rs

@@ -14,6 +14,7 @@ use rustc_ast::*;
 use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_hir as hir;
 use rustc_hir::def::{DefKind, Res};
+use rustc_middle::span_bug;
 use rustc_session::errors::report_lit_error;
 use rustc_span::source_map::{respan, Spanned};
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
@@ -328,9 +329,12 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     )
                 }
                 ExprKind::Yield(opt_expr) => self.lower_expr_yield(e.span, opt_expr.as_deref()),
-                ExprKind::Err => {
-                    hir::ExprKind::Err(self.dcx().span_delayed_bug(e.span, "lowered ExprKind::Err"))
+                ExprKind::Err(guar) => hir::ExprKind::Err(*guar),
+
+                ExprKind::Dummy => {
+                    span_bug!(e.span, "lowered ExprKind::Dummy")
                 }
+
                 ExprKind::Try(sub_expr) => self.lower_expr_try(e.span, sub_expr),
 
                 ExprKind::Paren(_) | ExprKind::ForLoop { .. } => {

compiler/rustc_ast_lowering/src/pat.rs

@@ -331,7 +331,8 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             ExprKind::Lit(..)
             | ExprKind::ConstBlock(..)
             | ExprKind::IncludedBytes(..)
-            | ExprKind::Err => {}
+            | ExprKind::Err(_)
+            | ExprKind::Dummy => {}
             ExprKind::Path(..) if allow_paths => {}
             ExprKind::Unary(UnOp::Neg, inner) if matches!(inner.kind, ExprKind::Lit(_)) => {}
             _ => {

compiler/rustc_ast_pretty/src/pprust/state/expr.rs

@@ -893,11 +893,16 @@ impl<'a> State<'a> {
                 self.word_nbsp("try");
                 self.print_block_with_attrs(blk, attrs)
             }
-            ast::ExprKind::Err => {
+            ast::ExprKind::Err(_) => {
                 self.popen();
                 self.word("/*ERROR*/");
                 self.pclose()
             }
+            ast::ExprKind::Dummy => {
+                self.popen();
+                self.word("/*DUMMY*/");
+                self.pclose();
+            }
         }
 
         self.ann.post(self, AnnNode::Expr(expr));

compiler/rustc_builtin_macros/src/asm.rs

@@ -13,7 +13,7 @@ use rustc_session::lint;
 use rustc_session::parse::ParseSess;
 use rustc_span::symbol::Ident;
 use rustc_span::symbol::{kw, sym, Symbol};
-use rustc_span::{InnerSpan, Span};
+use rustc_span::{ErrorGuaranteed, InnerSpan, Span};
 use rustc_target::asm::InlineAsmArch;
 use smallvec::smallvec;
 
@@ -433,7 +433,10 @@ fn parse_reg<'a>(
     Ok(result)
 }
 
-fn expand_preparsed_asm(ecx: &mut ExtCtxt<'_>, args: AsmArgs) -> Option<ast::InlineAsm> {
+fn expand_preparsed_asm(
+    ecx: &mut ExtCtxt<'_>,
+    args: AsmArgs,
+) -> Result<ast::InlineAsm, ErrorGuaranteed> {
     let mut template = vec![];
     // Register operands are implicitly used since they are not allowed to be
     // referenced in the template string.
@@ -459,10 +462,10 @@ fn expand_preparsed_asm(ecx: &mut ExtCtxt<'_>, args: AsmArgs) -> Option<ast::Inl
             match expr_to_spanned_string(ecx, template_expr, msg) {
                 Ok(template_part) => template_part,
                 Err(err) => {
-                    if let Some((err, _)) = err {
-                        err.emit();
-                    }
-                    return None;
+                    return Err(match err {
+                        Ok((err, _)) => err.emit(),
+                        Err(guar) => guar,
+                    });
                 }
             };
 
@@ -551,8 +554,8 @@ fn expand_preparsed_asm(ecx: &mut ExtCtxt<'_>, args: AsmArgs) -> Option<ast::Inl
                 let err_sp = template_span.from_inner(InnerSpan::new(span.start, span.end));
                 e.span_label(err_sp, label);
             }
-            e.emit();
-            return None;
+            let guar = e.emit();
+            return Err(guar);
         }
 
         curarg = parser.curarg;
@@ -719,7 +722,7 @@ fn expand_preparsed_asm(ecx: &mut ExtCtxt<'_>, args: AsmArgs) -> Option<ast::Inl
         }
     }
 
-    Some(ast::InlineAsm {
+    Ok(ast::InlineAsm {
         template,
         template_strs: template_strs.into_boxed_slice(),
         operands: args.operands,
@@ -736,22 +739,21 @@ pub(super) fn expand_asm<'cx>(
 ) -> Box<dyn base::MacResult + 'cx> {
     match parse_args(ecx, sp, tts, false) {
         Ok(args) => {
-            let expr = if let Some(inline_asm) = expand_preparsed_asm(ecx, args) {
-                P(ast::Expr {
+            let expr = match expand_preparsed_asm(ecx, args) {
+                Ok(inline_asm) => P(ast::Expr {
                     id: ast::DUMMY_NODE_ID,
                     kind: ast::ExprKind::InlineAsm(P(inline_asm)),
                     span: sp,
                     attrs: ast::AttrVec::new(),
                     tokens: None,
-                })
-            } else {
-                DummyResult::raw_expr(sp, true)
+                }),
+                Err(guar) => DummyResult::raw_expr(sp, Some(guar)),
             };
             MacEager::expr(expr)
         }
         Err(err) => {
-            err.emit();
-            DummyResult::any(sp)
+            let guar = err.emit();
+            DummyResult::any(sp, guar)
         }
     }
 }
@@ -762,28 +764,25 @@ pub(super) fn expand_global_asm<'cx>(
     tts: TokenStream,
 ) -> Box<dyn base::MacResult + 'cx> {
     match parse_args(ecx, sp, tts, true) {
-        Ok(args) => {
-            if let Some(inline_asm) = expand_preparsed_asm(ecx, args) {
-                MacEager::items(smallvec![P(ast::Item {
-                    ident: Ident::empty(),
-                    attrs: ast::AttrVec::new(),
-                    id: ast::DUMMY_NODE_ID,
-                    kind: ast::ItemKind::GlobalAsm(Box::new(inline_asm)),
-                    vis: ast::Visibility {
-                        span: sp.shrink_to_lo(),
-                        kind: ast::VisibilityKind::Inherited,
-                        tokens: None,
-                    },
-                    span: sp,
+        Ok(args) => match expand_preparsed_asm(ecx, args) {
+            Ok(inline_asm) => MacEager::items(smallvec![P(ast::Item {
+                ident: Ident::empty(),
+                attrs: ast::AttrVec::new(),
+                id: ast::DUMMY_NODE_ID,
+                kind: ast::ItemKind::GlobalAsm(Box::new(inline_asm)),
+                vis: ast::Visibility {
+                    span: sp.shrink_to_lo(),
+                    kind: ast::VisibilityKind::Inherited,
                     tokens: None,
-                })])
-            } else {
-                DummyResult::any(sp)
-            }
-        }
+                },
+                span: sp,
+                tokens: None,
+            })]),
+            Err(guar) => DummyResult::any(sp, guar),
+        },
         Err(err) => {
-            err.emit();
-            DummyResult::any(sp)
+            let guar = err.emit();
+            DummyResult::any(sp, guar)
         }
     }
 }

compiler/rustc_builtin_macros/src/assert.rs

@@ -23,8 +23,8 @@ pub fn expand_assert<'cx>(
     let Assert { cond_expr, custom_message } = match parse_assert(cx, span, tts) {
         Ok(assert) => assert,
         Err(err) => {
-            err.emit();
-            return DummyResult::any(span);
+            let guar = err.emit();
+            return DummyResult::any(span, guar);
         }
     };
 

compiler/rustc_builtin_macros/src/assert/context.rs

@@ -303,7 +303,8 @@ impl<'cx, 'a> Context<'cx, 'a> {
             | ExprKind::Closure(_)
             | ExprKind::ConstBlock(_)
             | ExprKind::Continue(_)
-            | ExprKind::Err
+            | ExprKind::Dummy
+            | ExprKind::Err(_)
             | ExprKind::Field(_, _)
             | ExprKind::ForLoop { .. }
             | ExprKind::FormatArgs(_)

compiler/rustc_builtin_macros/src/cfg.rs

@@ -8,14 +8,14 @@ use rustc_ast::token;
 use rustc_ast::tokenstream::TokenStream;
 use rustc_attr as attr;
 use rustc_errors::PResult;
-use rustc_expand::base::{self, *};
+use rustc_expand::base::{DummyResult, ExtCtxt, MacEager, MacResult};
 use rustc_span::Span;
 
 pub fn expand_cfg(
     cx: &mut ExtCtxt<'_>,
     sp: Span,
     tts: TokenStream,
-) -> Box<dyn base::MacResult + 'static> {
+) -> Box<dyn MacResult + 'static> {
     let sp = cx.with_def_site_ctxt(sp);
 
     match parse_cfg(cx, sp, tts) {
@@ -29,8 +29,8 @@ pub fn expand_cfg(
             MacEager::expr(cx.expr_bool(sp, matches_cfg))
         }
         Err(err) => {
-            err.emit();
-            DummyResult::any(sp)
+            let guar = err.emit();
+            DummyResult::any(sp, guar)
         }
     }
 }

compiler/rustc_builtin_macros/src/compile_error.rs

@@ -1,24 +1,22 @@
 // The compiler code necessary to support the compile_error! extension.
 
 use rustc_ast::tokenstream::TokenStream;
-use rustc_expand::base::{self, *};
+use rustc_expand::base::{get_single_str_from_tts, DummyResult, ExtCtxt, MacResult};
 use rustc_span::Span;
 
 pub fn expand_compile_error<'cx>(
     cx: &'cx mut ExtCtxt<'_>,
     sp: Span,
     tts: TokenStream,
-) -> Box<dyn base::MacResult + 'cx> {
-    let Some(var) = get_single_str_from_tts(cx, sp, tts, "compile_error!") else {
-        return DummyResult::any(sp);
+) -> Box<dyn MacResult + 'cx> {
+    let var = match get_single_str_from_tts(cx, sp, tts, "compile_error!") {
+        Ok(var) => var,
+        Err(guar) => return DummyResult::any(sp, guar),
     };
 
-    #[expect(
-        rustc::diagnostic_outside_of_impl,
-        reason = "diagnostic message is specified by user"
-    )]
+    #[expect(rustc::diagnostic_outside_of_impl, reason = "diagnostic message is specified by user")]
     #[expect(rustc::untranslatable_diagnostic, reason = "diagnostic message is specified by user")]
-    cx.dcx().span_err(sp, var.to_string());
+    let guar = cx.dcx().span_err(sp, var.to_string());
 
-    DummyResult::any(sp)
+    DummyResult::any(sp, guar)
 }