[EXPERIMENT] DelimSpan::from_single() experiment and UI tests update.

compiler/rustc_ast/src/tokenstream.rs

@@ -978,7 +978,54 @@ pub struct DelimSpan {
 
 impl DelimSpan {
     pub fn from_single(sp: Span) -> Self {
-        DelimSpan { open: sp, close: sp }
+        let default_open = sp.shrink_to_lo();
+        let default_close = sp.shrink_to_hi();
+
+        let Some(sm) = rustc_span::source_map::get_source_map() else {
+            // No source map available.
+            return Self { open: default_open, close: default_close };
+        };
+
+        let (open, close) = sm
+            .span_to_source(sp, |src, start, end| {
+                let Some(src) = src.get(start..end) else {
+                    return Ok((default_close, default_close));
+                };
+
+                // Only check the first and last characters.
+                // If there is white space or other characters
+                // other than `( ... )`, `[ ... ]`, and `{ ... }`.
+                // I assume that is intentionally included in this
+                // span so we don't want to shrink the span by
+                // searching for the delimiters, and setting
+                // the open and close spans to some more interior
+                // position.
+                let mut chars = src.chars();
+                // just using '_' as a place holder.
+                let first = chars.next().unwrap_or('_');
+                let last = chars.last().unwrap_or('_');
+
+                // Thought maybe scan through if first is '(', '[',  or '{'
+                // and see if the last matches up e.g. make sure it's not some
+                // extra mismatched delimiter.
+
+                let open = sp.subspan(0..first.len_utf8()).unwrap_or(default_open);
+
+                let len = (sp.hi() - sp.lo()).0 as usize;
+                let pos = len.checked_sub(last.len_utf8()).unwrap_or(0);
+                let close = sp.subspan(pos..).unwrap_or(default_close);
+
+                Ok(match (first, last) {
+                    ('(', ')') | ('{', '}') | ('[', ']') => (open, close),
+                    ('(', _) | ('{', _) | ('[', _) => (open, default_close),
+                    (_, ')') | (_, '}') | (_, ']') => (default_open, close),
+                    (_, _) => (default_close, default_open),
+                })
+            })
+            .ok()
+            .unwrap_or((default_open, default_close));
+
+        DelimSpan { open, close }
     }
 
     pub fn from_pair(open: Span, close: Span) -> Self {

compiler/rustc_span/src/lib.rs

@@ -77,7 +77,7 @@ use std::cmp::{self, Ordering};
 use std::fmt::Display;
 use std::hash::Hash;
 use std::io::{self, Read};
-use std::ops::{Add, Range, Sub};
+use std::ops::{Add, Bound, Range, RangeBounds, Sub};
 use std::path::{Path, PathBuf};
 use std::str::FromStr;
 use std::sync::Arc;
@@ -1176,6 +1176,37 @@ impl Span {
     pub fn normalize_to_macro_rules(self) -> Span {
         self.map_ctxt(|ctxt| ctxt.normalize_to_macro_rules())
     }
+
+    /// This function is similar to `Span::from_inner`, but it
+    /// will return `None` if the relative Range span exceeds
+    /// the bounds of span.
+    pub fn subspan<I: Copy, R: RangeBounds<I>>(self, subspan: R) -> Option<Span>
+    where
+        u32: TryFrom<I>,
+    {
+        let lo = self.lo().0;
+        let hi = self.hi().0;
+
+        let start = match subspan.start_bound() {
+            Bound::Included(s) => u32::try_from(*s).ok()?,
+            Bound::Excluded(s) => u32::try_from(*s).ok()?.checked_add(1)?,
+            Bound::Unbounded => 0,
+        };
+
+        let end = match subspan.end_bound() {
+            Bound::Included(e) => u32::try_from(*e).ok()?.checked_add(1)?,
+            Bound::Excluded(e) => u32::try_from(*e).ok()?,
+            Bound::Unbounded => hi - lo,
+        };
+
+        let new_lo = lo.checked_add(start)?;
+        let new_hi = lo.checked_add(end)?;
+        if new_lo > hi || new_hi > hi {
+            return None;
+        }
+
+        Some(self.with_lo(BytePos(new_lo)).with_hi(BytePos(new_hi)))
+    }
 }
 
 impl Default for Span {

src/tools/clippy/tests/ui/uninhabited_references.stderr

@@ -11,7 +11,7 @@ error: dereferencing a reference to an uninhabited type would be undefined behav
   --> tests/ui/uninhabited_references.rs:12:30
    |
 LL |         fn $name(x: &$ty) -> &$ty {
-   |                              ^^^^
+   |                              ^
 ...
 LL | ret_something!(id_never, !);
    | --------------------------- in this macro invocation

tests/ui/attributes/nonterminal-expansion.stderr

@@ -1,8 +1,8 @@
 error: expected a literal (`1u8`, `1.0f32`, `"string"`, etc.) here, found `expr` metavariable
-  --> $DIR/nonterminal-expansion.rs:7:22
+  --> $DIR/nonterminal-expansion.rs:7:24
    |
 LL |         #[repr(align($n))]
-   |                      ^^
+   |                        ^
 ...
 LL | pass_nonterminal!(n!());
    | ----------------------- in this macro invocation

tests/ui/borrowck/span-semicolon-issue-139049.stderr

@@ -2,7 +2,7 @@ error[E0597]: `l` does not live long enough
   --> $DIR/span-semicolon-issue-139049.rs:11:41
    |
 LL | macro_rules! perform { ($e:expr) => { D(&$e).end() } }
-   |                                       --^^^-
+   |                                       --^---
    |                                       | |
    |                                       | borrowed value does not live long enough
    |                                       a temporary with access to the borrow is created here ...
@@ -24,7 +24,7 @@ error[E0597]: `l` does not live long enough
   --> $DIR/span-semicolon-issue-139049.rs:11:41
    |
 LL | macro_rules! perform { ($e:expr) => { D(&$e).end() } }
-   |                                       --^^^-
+   |                                       --^---
    |                                       | |
    |                                       | borrowed value does not live long enough
    |                                       a temporary with access to the borrow is created here ...

tests/ui/closures/2229_closure_analysis/migrations/closure-body-macro-fragment.rs

@@ -1,4 +1,3 @@
-//@ run-rustfix
 //@ edition:2018
 //@ check-pass
 #![warn(rust_2021_compatibility)]
@@ -25,7 +24,6 @@ macro_rules! m {
 fn main() {
     let a = (Foo(0), Foo(1));
     m!({
-        //~^ HELP: add a dummy
         let x = a.0;
         println!("{:?}", x);
     });

tests/ui/closures/2229_closure_analysis/migrations/closure-body-macro-fragment.stderr

@@ -1,5 +1,5 @@
 warning: changes to closure capture in Rust 2021 will affect drop order
-  --> $DIR/closure-body-macro-fragment.rs:16:17
+  --> $DIR/closure-body-macro-fragment.rs:15:17
    |
 LL |           let f = || $body;
    |                   ^^
@@ -8,7 +8,6 @@ LL |       }};
    |       - in Rust 2018, `a` is dropped here, but in Rust 2021, only `a.0` will be dropped here as part of the closure
 ...
 LL | /     m!({
-LL | |
 LL | |         let x = a.0;
    | |                 --- in Rust 2018, this closure captures all of `a`, but in Rust 2021, it will only capture `a.0`
 LL | |         println!("{:?}", x);
@@ -17,17 +16,16 @@ LL | |     });
    |
    = note: for more information, see <https://doc.rust-lang.org/edition-guide/rust-2021/disjoint-capture-in-closures.html>
 note: the lint level is defined here
-  --> $DIR/closure-body-macro-fragment.rs:4:9
+  --> $DIR/closure-body-macro-fragment.rs:3:9
    |
 LL | #![warn(rust_2021_compatibility)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^
    = note: `#[warn(rust_2021_incompatible_closure_captures)]` implied by `#[warn(rust_2021_compatibility)]`
    = note: this warning originates in the macro `m` (in Nightly builds, run with -Z macro-backtrace for more info)
 help: add a dummy let to cause `a` to be fully captured
    |
-LL ~     m!({
-LL +         let _ = &a;
-   |
+LL |         m!(@ $body{ let _ = &a;  });
+   |                   +++++++++++++  +
 
 warning: 1 warning emitted
 

tests/ui/conditional-compilation/cfg-attr-syntax-validation.stderr

@@ -92,10 +92,10 @@ LL | #[cfg(a = b"hi")]
    = note: expected a normal string literal, not a byte string literal
 
 error: expected a literal (`1u8`, `1.0f32`, `"string"`, etc.) here, found `expr` metavariable
-  --> $DIR/cfg-attr-syntax-validation.rs:51:25
+  --> $DIR/cfg-attr-syntax-validation.rs:51:30
    |
 LL |         #[cfg(feature = $expr)]
-   |                         ^^^^^
+   |                              ^
 ...
 LL | generate_s10!(concat!("nonexistent"));
    | ------------------------------------- in this macro invocation

tests/ui/conditional-compilation/cfg_attr-attr-syntax-validation.stderr

@@ -92,10 +92,10 @@ LL | #[cfg_attr(true)]
    = note: for more information, visit <https://doc.rust-lang.org/reference/conditional-compilation.html#the-cfg_attr-attribute>
 
 error: expected a literal (`1u8`, `1.0f32`, `"string"`, etc.) here, found `expr` metavariable
-  --> $DIR/cfg_attr-attr-syntax-validation.rs:30:30
+  --> $DIR/cfg_attr-attr-syntax-validation.rs:30:35
    |
 LL |         #[cfg_attr(feature = $expr)]
-   |         ---------------------^^^^^-- help: must be of the form: `#[cfg_attr(predicate, attr1, attr2, ...)]`
+   |         --------------------------^- help: must be of the form: `#[cfg_attr(predicate, attr1, attr2, ...)]`
 ...
 LL | generate_s10!(concat!("nonexistent"));
    | ------------------------------------- in this macro invocation

tests/ui/did_you_mean/bad-assoc-expr.stderr

@@ -90,16 +90,16 @@ error: missing angle brackets in associated item path
   --> $DIR/bad-assoc-expr.rs:23:19
    |
 LL |     ($ty: ty) => ($ty::clone(&0))
-   |                   ^^^
+   |                   ^
 ...
 LL |     expr!(u8);
    |     --------- in this macro invocation
    |
    = note: this error originates in the macro `expr` (in Nightly builds, run with -Z macro-backtrace for more info)
 help: types that don't start with an identifier need to be surrounded with angle brackets in qualified paths
    |
-LL |     ($ty: ty) => (<$ty>::clone(&0))
-   |                   +   +
+LL |     ($ty: ty) => (<>$ty::clone(&0))
+   |                   ++
 
 error: aborting due to 9 previous errors
 

tests/ui/did_you_mean/bad-assoc-pat.stderr

@@ -57,16 +57,16 @@ error: missing angle brackets in associated item path
   --> $DIR/bad-assoc-pat.rs:21:19
    |
 LL |     ($ty: ty) => ($ty::AssocItem)
-   |                   ^^^
+   |                   ^
 ...
 LL |         pat!(u8) => {}
    |         -------- in this macro invocation
    |
    = note: this error originates in the macro `pat` (in Nightly builds, run with -Z macro-backtrace for more info)
 help: types that don't start with an identifier need to be surrounded with angle brackets in qualified paths
    |
-LL |     ($ty: ty) => (<$ty>::AssocItem)
-   |                   +   +
+LL |     ($ty: ty) => (<>$ty::AssocItem)
+   |                   ++
 
 error[E0599]: no associated item named `AssocItem` found for slice `[u8]` in the current scope
   --> $DIR/bad-assoc-pat.rs:3:15

tests/ui/did_you_mean/bad-assoc-ty.edition2015.stderr

@@ -90,16 +90,16 @@ error: missing angle brackets in associated item path
   --> $DIR/bad-assoc-ty.rs:44:19
    |
 LL |     ($ty: ty) => ($ty::AssocTy);
-   |                   ^^^
+   |                   ^
 ...
 LL | type J = ty!(u8);
    |          ------- in this macro invocation
    |
    = note: this error originates in the macro `ty` (in Nightly builds, run with -Z macro-backtrace for more info)
 help: types that don't start with an identifier need to be surrounded with angle brackets in qualified paths
    |
-LL |     ($ty: ty) => (<$ty>::AssocTy);
-   |                   +   +
+LL |     ($ty: ty) => (<>$ty::AssocTy);
+   |                   ++
 
 error[E0223]: ambiguous associated type
   --> $DIR/bad-assoc-ty.rs:5:10

tests/ui/did_you_mean/bad-assoc-ty.edition2021.stderr

@@ -90,16 +90,16 @@ error: missing angle brackets in associated item path
   --> $DIR/bad-assoc-ty.rs:44:19
    |
 LL |     ($ty: ty) => ($ty::AssocTy);
-   |                   ^^^
+   |                   ^
 ...
 LL | type J = ty!(u8);
    |          ------- in this macro invocation
    |
    = note: this error originates in the macro `ty` (in Nightly builds, run with -Z macro-backtrace for more info)
 help: types that don't start with an identifier need to be surrounded with angle brackets in qualified paths
    |
-LL |     ($ty: ty) => (<$ty>::AssocTy);
-   |                   +   +
+LL |     ($ty: ty) => (<>$ty::AssocTy);
+   |                   ++
 
 error[E0223]: ambiguous associated type
   --> $DIR/bad-assoc-ty.rs:5:10

tests/ui/half-open-range-patterns/half-open-range-pats-inclusive-dotdotdot-bad-syntax.stderr

@@ -66,7 +66,7 @@ error[E0005]: refutable pattern in local binding
   --> $DIR/half-open-range-pats-inclusive-dotdotdot-bad-syntax.rs:25:17
    |
 LL |             let ...$e;
-   |                 ^^^^^ pattern `1_i32..=i32::MAX` not covered
+   |                 ^^^ pattern `1_i32..=i32::MAX` not covered
 ...
 LL |     mac!(0);
    |     ------- in this macro invocation

tests/ui/half-open-range-patterns/half-open-range-pats-inclusive-no-end.stderr

@@ -85,10 +85,10 @@ LL +             let $e..;
    |
 
 error[E0005]: refutable pattern in local binding
-  --> $DIR/half-open-range-pats-inclusive-no-end.rs:18:17
+  --> $DIR/half-open-range-pats-inclusive-no-end.rs:18:19
    |
 LL |             let $e...;
-   |                 ^^^^^ pattern `i32::MIN..=-1_i32` not covered
+   |                   ^^^ pattern `i32::MIN..=-1_i32` not covered
 ...
 LL |     mac!(0);
    |     ------- in this macro invocation
@@ -99,10 +99,10 @@ LL |     mac!(0);
    = note: this error originates in the macro `mac` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0005]: refutable pattern in local binding
-  --> $DIR/half-open-range-pats-inclusive-no-end.rs:20:17
+  --> $DIR/half-open-range-pats-inclusive-no-end.rs:20:19
    |
 LL |             let $e..=;
-   |                 ^^^^^ pattern `i32::MIN..=-1_i32` not covered
+   |                   ^^^ pattern `i32::MIN..=-1_i32` not covered
 ...
 LL |     mac!(0);
    |     ------- in this macro invocation

tests/ui/imports/import-prefix-macro-2.stderr

@@ -1,8 +1,8 @@
 error: expected identifier, found metavariable
-  --> $DIR/import-prefix-macro-2.rs:11:26
+  --> $DIR/import-prefix-macro-2.rs:11:28
    |
 LL |     ($p: path) => (use ::$p {S, Z});
-   |                          ^^ expected identifier, found metavariable
+   |                            ^ expected identifier, found metavariable
 ...
 LL | import! { a::b::c }
    | ------------------- in this macro invocation

tests/ui/lint/lint-double-negations-macro.stderr

@@ -2,7 +2,7 @@ warning: use of a double negation
   --> $DIR/lint-double-negations-macro.rs:9:9
    |
 LL |         --$e
-   |         ^^^^
+   |         ^^
 ...
 LL |     bad_macro!(1);
    |     ------------- in this macro invocation
@@ -13,8 +13,8 @@ LL |     bad_macro!(1);
    = note: this warning originates in the macro `bad_macro` (in Nightly builds, run with -Z macro-backtrace for more info)
 help: add parentheses for clarity
    |
-LL |         -(-$e)
-   |          +   +
+LL |         -(-)$e
+   |          + +
 
 warning: 1 warning emitted