Rollup merge of #130349 - ShE3py:break_up_float, r=fmease

Fix `Parser::break_up_float`'s right span

```rs
use std::mem::offset_of;

fn main() {
    offset_of!((u8,), 0.0);
}
```
Before:
```
error[E0609]: no field `0` on type `u8`
    --> ./main.rs:4:25
     |
4    |       offset_of!((u8,), 0.0);
     |  _____--------------------^-
     | |     |
     | |     in this macro invocation
5    | | }
...    |
     |
     = note: this error originates in the macro `offset_of` (in Nightly builds, run with -Z macro-backtrace for more info)

error: aborting due to 1 previous error
```
After:
```
error[E0609]: no field `0` on type `u8`
 --> ./main.rs:4:25
  |
4 |     offset_of!((u8,), 0.0);
  |                         ^

error: aborting due to 1 previous error
```

---
`@rustbot` label +A-parser +D-imprecise-spans

3 files changed, 56 insertions, 58 deletions

diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
index 2d6edad2977..2d5a1914fa6 100644
--- a/compiler/rustc_parse/src/parser/expr.rs
+++ b/compiler/rustc_parse/src/parser/expr.rs
@@ -49,7 +49,7 @@ enum DestructuredFloat {
     /// 1.2 | 1.2e3
     MiddleDot(Symbol, Span, Span, Symbol, Span),
     /// Invalid
-    Error,
+    Error(ErrorGuaranteed),
 }
 
 impl<'a> Parser<'a> {
@@ -1008,7 +1008,7 @@ impl<'a> Parser<'a> {
                             self.mk_expr_tuple_field_access(lo, ident1_span, base, sym1, None);
                         self.mk_expr_tuple_field_access(lo, ident2_span, base1, sym2, suffix)
                     }
-                    DestructuredFloat::Error => base,
+                    DestructuredFloat::Error(_) => base,
                 })
             }
             _ => {
@@ -1018,7 +1018,7 @@ impl<'a> Parser<'a> {
         }
     }
 
-    fn error_unexpected_after_dot(&self) {
+    fn error_unexpected_after_dot(&self) -> ErrorGuaranteed {
         let actual = pprust::token_to_string(&self.token);
         let span = self.token.span;
         let sm = self.psess.source_map();
@@ -1028,17 +1028,19 @@ impl<'a> Parser<'a> {
             }
             _ => (span, actual),
         };
-        self.dcx().emit_err(errors::UnexpectedTokenAfterDot { span, actual });
+        self.dcx().emit_err(errors::UnexpectedTokenAfterDot { span, actual })
     }
 
-    // We need an identifier or integer, but the next token is a float.
-    // Break the float into components to extract the identifier or integer.
+    /// We need an identifier or integer, but the next token is a float.
+    /// Break the float into components to extract the identifier or integer.
+    ///
+    /// See also [`TokenKind::break_two_token_op`] which does similar splitting of `>>` into `>`.
+    //
     // FIXME: With current `TokenCursor` it's hard to break tokens into more than 2
-    // parts unless those parts are processed immediately. `TokenCursor` should either
-    // support pushing "future tokens" (would be also helpful to `break_and_eat`), or
-    // we should break everything including floats into more basic proc-macro style
-    // tokens in the lexer (probably preferable).
-    // See also `TokenKind::break_two_token_op` which does similar splitting of `>>` into `>`.
+    //  parts unless those parts are processed immediately. `TokenCursor` should either
+    //  support pushing "future tokens" (would be also helpful to `break_and_eat`), or
+    //  we should break everything including floats into more basic proc-macro style
+    //  tokens in the lexer (probably preferable).
     fn break_up_float(&self, float: Symbol, span: Span) -> DestructuredFloat {
         #[derive(Debug)]
         enum FloatComponent {
@@ -1078,34 +1080,30 @@ impl<'a> Parser<'a> {
                 DestructuredFloat::Single(Symbol::intern(i), span)
             }
             // 1.
-            [IdentLike(i), Punct('.')] => {
-                let (ident_span, dot_span) = if can_take_span_apart() {
-                    let (span, ident_len) = (span.data(), BytePos::from_usize(i.len()));
-                    let ident_span = span.with_hi(span.lo + ident_len);
-                    let dot_span = span.with_lo(span.lo + ident_len);
-                    (ident_span, dot_span)
+            [IdentLike(left), Punct('.')] => {
+                let (left_span, dot_span) = if can_take_span_apart() {
+                    let left_span = span.with_hi(span.lo() + BytePos::from_usize(left.len()));
+                    let dot_span = span.with_lo(left_span.hi());
+                    (left_span, dot_span)
                 } else {
                     (span, span)
                 };
-                let symbol = Symbol::intern(i);
-                DestructuredFloat::TrailingDot(symbol, ident_span, dot_span)
+                let left = Symbol::intern(left);
+                DestructuredFloat::TrailingDot(left, left_span, dot_span)
             }
             // 1.2 | 1.2e3
-            [IdentLike(i1), Punct('.'), IdentLike(i2)] => {
-                let (ident1_span, dot_span, ident2_span) = if can_take_span_apart() {
-                    let (span, ident1_len) = (span.data(), BytePos::from_usize(i1.len()));
-                    let ident1_span = span.with_hi(span.lo + ident1_len);
-                    let dot_span = span
-                        .with_lo(span.lo + ident1_len)
-                        .with_hi(span.lo + ident1_len + BytePos(1));
-                    let ident2_span = self.token.span.with_lo(span.lo + ident1_len + BytePos(1));
-                    (ident1_span, dot_span, ident2_span)
+            [IdentLike(left), Punct('.'), IdentLike(right)] => {
+                let (left_span, dot_span, right_span) = if can_take_span_apart() {
+                    let left_span = span.with_hi(span.lo() + BytePos::from_usize(left.len()));
+                    let dot_span = span.with_lo(left_span.hi()).with_hi(left_span.hi() + BytePos(1));
+                    let right_span = span.with_lo(dot_span.hi());
+                    (left_span, dot_span, right_span)
                 } else {
                     (span, span, span)
                 };
-                let symbol1 = Symbol::intern(i1);
-                let symbol2 = Symbol::intern(i2);
-                DestructuredFloat::MiddleDot(symbol1, ident1_span, dot_span, symbol2, ident2_span)
+                let left = Symbol::intern(left);
+                let right = Symbol::intern(right);
+                DestructuredFloat::MiddleDot(left, left_span, dot_span, right, right_span)
             }
             // 1e+ | 1e- (recovered)
             [IdentLike(_), Punct('+' | '-')] |
@@ -1116,8 +1114,8 @@ impl<'a> Parser<'a> {
             // 1.2e+3 | 1.2e-3
             [IdentLike(_), Punct('.'), IdentLike(_), Punct('+' | '-'), IdentLike(_)] => {
                 // See the FIXME about `TokenCursor` above.
-                self.error_unexpected_after_dot();
-                DestructuredFloat::Error
+                let guar = self.error_unexpected_after_dot();
+                DestructuredFloat::Error(guar)
             }
             _ => panic!("unexpected components in a float token: {components:?}"),
         }
@@ -1183,7 +1181,7 @@ impl<'a> Parser<'a> {
                                 fields.insert(start_idx, Ident::new(symbol2, span2));
                                 fields.insert(start_idx, Ident::new(symbol1, span1));
                             }
-                            DestructuredFloat::Error => {
+                            DestructuredFloat::Error(_) => {
                                 trailing_dot = None;
                                 fields.insert(start_idx, Ident::new(symbol, self.prev_token.span));
                             }
diff --git a/tests/ui/offset-of/offset-of-tuple.rs b/tests/ui/offset-of/offset-of-tuple.rs
index b0822352c9d..db00fe05583 100644
--- a/tests/ui/offset-of/offset-of-tuple.rs
+++ b/tests/ui/offset-of/offset-of-tuple.rs
@@ -28,6 +28,7 @@ type ComplexTup = (((u8, u8), u8), u8);
 
 fn nested() {
     offset_of!(((u8, u16), (u32, u16, u8)), 0.2); //~ ERROR no field `2`
+    offset_of!(((u8, u16), (u32, u16, u8)), 0.1e2); //~ ERROR no field `1e2`
     offset_of!(((u8, u16), (u32, u16, u8)), 1.2);
     offset_of!(((u8, u16), (u32, u16, u8)), 1.2.0); //~ ERROR no field `0`
 
diff --git a/tests/ui/offset-of/offset-of-tuple.stderr b/tests/ui/offset-of/offset-of-tuple.stderr
index e6b45c0b6b8..dd20859e04e 100644
--- a/tests/ui/offset-of/offset-of-tuple.stderr
+++ b/tests/ui/offset-of/offset-of-tuple.stderr
@@ -29,43 +29,43 @@ LL |     { builtin # offset_of((u8, u8), 1 .) };
    |                                        ^
 
 error: unexpected token: `)`
-  --> $DIR/offset-of-tuple.rs:46:45
+  --> $DIR/offset-of-tuple.rs:47:45
    |
 LL |     { builtin # offset_of(ComplexTup, 0.0.1.) };
    |                                             ^
 
 error: unexpected token: `)`
-  --> $DIR/offset-of-tuple.rs:47:46
+  --> $DIR/offset-of-tuple.rs:48:46
    |
 LL |     { builtin # offset_of(ComplexTup, 0 .0.1.) };
    |                                              ^
 
 error: unexpected token: `)`
-  --> $DIR/offset-of-tuple.rs:48:47
+  --> $DIR/offset-of-tuple.rs:49:47
    |
 LL |     { builtin # offset_of(ComplexTup, 0 . 0.1.) };
    |                                               ^
 
 error: unexpected token: `)`
-  --> $DIR/offset-of-tuple.rs:49:46
+  --> $DIR/offset-of-tuple.rs:50:46
    |
 LL |     { builtin # offset_of(ComplexTup, 0. 0.1.) };
    |                                              ^
 
 error: unexpected token: `)`
-  --> $DIR/offset-of-tuple.rs:50:46
+  --> $DIR/offset-of-tuple.rs:51:46
    |
 LL |     { builtin # offset_of(ComplexTup, 0.0 .1.) };
    |                                              ^
 
 error: unexpected token: `)`
-  --> $DIR/offset-of-tuple.rs:51:47
+  --> $DIR/offset-of-tuple.rs:52:47
    |
 LL |     { builtin # offset_of(ComplexTup, 0.0 . 1.) };
    |                                               ^
 
 error: unexpected token: `)`
-  --> $DIR/offset-of-tuple.rs:52:46
+  --> $DIR/offset-of-tuple.rs:53:46
    |
 LL |     { builtin # offset_of(ComplexTup, 0.0. 1.) };
    |                                              ^
@@ -104,43 +104,43 @@ LL |     offset_of!((u8, u8), 1 .);
    |                             ^
 
 error: unexpected token: `)`
-  --> $DIR/offset-of-tuple.rs:35:34
+  --> $DIR/offset-of-tuple.rs:36:34
    |
 LL |     offset_of!(ComplexTup, 0.0.1.);
    |                                  ^
 
 error: unexpected token: `)`
-  --> $DIR/offset-of-tuple.rs:36:35
+  --> $DIR/offset-of-tuple.rs:37:35
    |
 LL |     offset_of!(ComplexTup, 0 .0.1.);
    |                                   ^
 
 error: unexpected token: `)`
-  --> $DIR/offset-of-tuple.rs:37:36
+  --> $DIR/offset-of-tuple.rs:38:36
    |
 LL |     offset_of!(ComplexTup, 0 . 0.1.);
    |                                    ^
 
 error: unexpected token: `)`
-  --> $DIR/offset-of-tuple.rs:38:35
+  --> $DIR/offset-of-tuple.rs:39:35
    |
 LL |     offset_of!(ComplexTup, 0. 0.1.);
    |                                   ^
 
 error: unexpected token: `)`
-  --> $DIR/offset-of-tuple.rs:39:35
+  --> $DIR/offset-of-tuple.rs:40:35
    |
 LL |     offset_of!(ComplexTup, 0.0 .1.);
    |                                   ^
 
 error: unexpected token: `)`
-  --> $DIR/offset-of-tuple.rs:40:36
+  --> $DIR/offset-of-tuple.rs:41:36
    |
 LL |     offset_of!(ComplexTup, 0.0 . 1.);
    |                                    ^
 
 error: unexpected token: `)`
-  --> $DIR/offset-of-tuple.rs:41:35
+  --> $DIR/offset-of-tuple.rs:42:35
    |
 LL |     offset_of!(ComplexTup, 0.0. 1.);
    |                                   ^
@@ -196,22 +196,21 @@ LL |     builtin # offset_of((u8, u8), 1_u8);
 error[E0609]: no field `2` on type `(u8, u16)`
   --> $DIR/offset-of-tuple.rs:30:47
    |
-LL |       offset_of!(((u8, u16), (u32, u16, u8)), 0.2);
-   |  _____------------------------------------------^-
-   | |     |
-   | |     in this macro invocation
-LL | |     offset_of!(((u8, u16), (u32, u16, u8)), 1.2);
-LL | |     offset_of!(((u8, u16), (u32, u16, u8)), 1.2.0);
-...  |
+LL |     offset_of!(((u8, u16), (u32, u16, u8)), 0.2);
+   |                                               ^
+
+error[E0609]: no field `1e2` on type `(u8, u16)`
+  --> $DIR/offset-of-tuple.rs:31:47
    |
-   = note: this error originates in the macro `offset_of` (in Nightly builds, run with -Z macro-backtrace for more info)
+LL |     offset_of!(((u8, u16), (u32, u16, u8)), 0.1e2);
+   |                                               ^^^
 
 error[E0609]: no field `0` on type `u8`
-  --> $DIR/offset-of-tuple.rs:32:49
+  --> $DIR/offset-of-tuple.rs:33:49
    |
 LL |     offset_of!(((u8, u16), (u32, u16, u8)), 1.2.0);
    |                                                 ^
 
-error: aborting due to 33 previous errors
+error: aborting due to 34 previous errors
 
 For more information about this error, try `rustc --explain E0609`.