Rollup merge of #144711 - compiler-errors:op-span, r=petrochenkov

Consider operator's span when computing binop expr span

When computing the span of a binop consisting of `lhs` and `rhs`, we previously just took the spans of `lhs.span.to(rhs.span)`. In the case that both `lhs` and `rhs` are both arguments to a macro, this can produce a wildly incorrect span.

To fix this, first compute the span between `lhs` and the binary operator, which will cause `lhs` to possibly be adjusted to a relevant macro metavar, and then compute that span extended to `rhs`, which will cause it to also be adjusted to a relevant macro metavar.

This coincidentally fixes a FIXME in `tests/ui/lint/wide_pointer_comparisons.rs` and suppresses a nonsense suggestion.

Author: jdonszelmann

compiler/rustc_parse/src/parser/expr.rs

@@ -263,10 +263,11 @@ impl<'a> Parser<'a> {
                 continue;
             }
 
+            let op_span = op.span;
             let op = op.node;
             // Special cases:
             if op == AssocOp::Cast {
-                lhs = self.parse_assoc_op_cast(lhs, lhs_span, ExprKind::Cast)?;
+                lhs = self.parse_assoc_op_cast(lhs, lhs_span, op_span, ExprKind::Cast)?;
                 continue;
             } else if let AssocOp::Range(limits) = op {
                 // If we didn't have to handle `x..`/`x..=`, it would be pretty easy to
@@ -284,7 +285,7 @@ impl<'a> Parser<'a> {
                 this.parse_expr_assoc_with(min_prec, attrs)
             })?;
 
-            let span = self.mk_expr_sp(&lhs, lhs_span, rhs.span);
+            let span = self.mk_expr_sp(&lhs, lhs_span, op_span, rhs.span);
             lhs = match op {
                 AssocOp::Binary(ast_op) => {
                     let binary = self.mk_binary(source_map::respan(cur_op_span, ast_op), lhs, rhs);
@@ -429,7 +430,7 @@ impl<'a> Parser<'a> {
             None
         };
         let rhs_span = rhs.as_ref().map_or(cur_op_span, |x| x.span);
-        let span = self.mk_expr_sp(&lhs, lhs.span, rhs_span);
+        let span = self.mk_expr_sp(&lhs, lhs.span, cur_op_span, rhs_span);
         let range = self.mk_range(Some(lhs), rhs, limits);
         Ok(self.mk_expr(span, range))
     }
@@ -654,10 +655,11 @@ impl<'a> Parser<'a> {
         &mut self,
         lhs: P<Expr>,
         lhs_span: Span,
+        op_span: Span,
         expr_kind: fn(P<Expr>, P<Ty>) -> ExprKind,
     ) -> PResult<'a, P<Expr>> {
         let mk_expr = |this: &mut Self, lhs: P<Expr>, rhs: P<Ty>| {
-            this.mk_expr(this.mk_expr_sp(&lhs, lhs_span, rhs.span), expr_kind(lhs, rhs))
+            this.mk_expr(this.mk_expr_sp(&lhs, lhs_span, op_span, rhs.span), expr_kind(lhs, rhs))
         };
 
         // Save the state of the parser before parsing type normally, in case there is a
@@ -4005,11 +4007,12 @@ impl<'a> Parser<'a> {
 
     /// Create expression span ensuring the span of the parent node
     /// is larger than the span of lhs and rhs, including the attributes.
-    fn mk_expr_sp(&self, lhs: &P<Expr>, lhs_span: Span, rhs_span: Span) -> Span {
+    fn mk_expr_sp(&self, lhs: &P<Expr>, lhs_span: Span, op_span: Span, rhs_span: Span) -> Span {
         lhs.attrs
             .iter()
             .find(|a| a.style == AttrStyle::Outer)
             .map_or(lhs_span, |a| a.span)
+            .to(op_span)
             .to(rhs_span)
     }
 

compiler/rustc_parse/src/validate_attr.rs

@@ -106,7 +106,7 @@ pub fn parse_meta<'a>(psess: &'a ParseSess, attr: &Attribute) -> PResult<'a, Met
                     res
                 } else {
                     // Example cases:
-                    // - `#[foo = 1+1]`: results in `ast::ExprKind::BinOp`.
+                    // - `#[foo = 1+1]`: results in `ast::ExprKind::Binary`.
                     // - `#[foo = include_str!("nonexistent-file.rs")]`:
                     //   results in `ast::ExprKind::Err`. In that case we delay
                     //   the error because an earlier error will have already

tests/ui/lint/wide_pointer_comparisons.rs

@@ -146,12 +146,10 @@ fn main() {
     {
         macro_rules! cmp {
             ($a:tt, $b:tt) => { $a == $b }
+            //~^ WARN ambiguous wide pointer comparison
         }
 
-        // FIXME: This lint uses some custom span combination logic.
-        // Rewrite it to adapt to the new metavariable span rules.
         cmp!(a, b);
-        //~^ WARN ambiguous wide pointer comparison
     }
 
     {

tests/ui/lint/wide_pointer_comparisons.stderr

@@ -720,18 +720,20 @@ LL +         std::ptr::eq(*a, *b)
    |
 
 warning: ambiguous wide pointer comparison, the comparison includes metadata which may not be expected
-  --> $DIR/wide_pointer_comparisons.rs:153:14
+  --> $DIR/wide_pointer_comparisons.rs:148:33
    |
+LL |             ($a:tt, $b:tt) => { $a == $b }
+   |                                 ^^^^^^^^
+...
 LL |         cmp!(a, b);
-   |              ^^^^
-   |
-help: use `std::ptr::addr_eq` or untyped pointers to only compare their addresses
+   |         ---------- in this macro invocation
    |
-LL |         cmp!(std::ptr::addr_eq(a, b));
-   |              ++++++++++++++++++    +
+   = help: use explicit `std::ptr::eq` method to compare metadata and addresses
+   = help: use `std::ptr::addr_eq` or untyped pointers to only compare their addresses
+   = note: this warning originates in the macro `cmp` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 warning: ambiguous wide pointer comparison, the comparison includes metadata which may not be expected
-  --> $DIR/wide_pointer_comparisons.rs:159:39
+  --> $DIR/wide_pointer_comparisons.rs:157:39
    |
 LL |             ($a:ident, $b:ident) => { $a == $b }
    |                                       ^^^^^^^^
@@ -747,7 +749,7 @@ LL +             ($a:ident, $b:ident) => { std::ptr::addr_eq($a, $b) }
    |
 
 warning: ambiguous wide pointer comparison, the comparison includes metadata which may not be expected
-  --> $DIR/wide_pointer_comparisons.rs:169:37
+  --> $DIR/wide_pointer_comparisons.rs:167:37
    |
 LL |             ($a:expr, $b:expr) => { $a == $b }
    |                                     ^^^^^^^^