Auto merge of #105363 - WaffleLapkin:thin2win_box_next_argument, r=nnethercote

Shrink `rustc_parse_format::Piece`

This makes both variants closer together in size (previously they were different by 208 bytes -- 16 vs 224). This may make things worse, but it's worth a try.

r? `@nnethercote`

Cargo.lock

@@ -4168,6 +4168,7 @@ dependencies = [
 name = "rustc_parse_format"
 version = "0.0.0"
 dependencies = [
+ "rustc_data_structures",
  "rustc_lexer",
 ]
 

compiler/rustc_builtin_macros/src/format.rs

@@ -333,7 +333,7 @@ pub fn make_format_args(
             parse::Piece::String(s) => {
                 unfinished_literal.push_str(s);
             }
-            parse::Piece::NextArgument(parse::Argument { position, position_span, format }) => {
+            parse::Piece::NextArgument(box parse::Argument { position, position_span, format }) => {
                 if !unfinished_literal.is_empty() {
                     template.push(FormatArgsPiece::Literal(Symbol::intern(&unfinished_literal)));
                     unfinished_literal.clear();

compiler/rustc_parse_format/Cargo.toml

@@ -5,3 +5,4 @@ edition = "2021"
 
 [dependencies]
 rustc_lexer = { path = "../rustc_lexer" }
+rustc_data_structures = { path = "../rustc_data_structures" }

compiler/rustc_parse_format/src/lib.rs

@@ -58,13 +58,13 @@ impl InnerOffset {
 
 /// A piece is a portion of the format string which represents the next part
 /// to emit. These are emitted as a stream by the `Parser` class.
-#[derive(Copy, Clone, Debug, PartialEq)]
+#[derive(Clone, Debug, PartialEq)]
 pub enum Piece<'a> {
     /// A literal string which should directly be emitted
     String(&'a str),
     /// This describes that formatting should process the next argument (as
     /// specified inside) for emission.
-    NextArgument(Argument<'a>),
+    NextArgument(Box<Argument<'a>>),
 }
 
 /// Representation of an argument specification.
@@ -244,7 +244,7 @@ impl<'a> Iterator for Parser<'a> {
                         } else {
                             self.suggest_positional_arg_instead_of_captured_arg(arg);
                         }
-                        Some(NextArgument(arg))
+                        Some(NextArgument(Box::new(arg)))
                     }
                 }
                 '}' => {
@@ -908,5 +908,9 @@ fn find_skips_from_snippet(
     (skips, true)
 }
 
+// Assert a reasonable size for `Piece`
+#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
+rustc_data_structures::static_assert_size!(Piece<'_>, 16);
+
 #[cfg(test)]
 mod tests;

compiler/rustc_parse_format/src/tests.rs

@@ -76,51 +76,51 @@ fn invalid_precision() {
 fn format_nothing() {
     same(
         "{}",
-        &[NextArgument(Argument {
+        &[NextArgument(Box::new(Argument {
             position: ArgumentImplicitlyIs(0),
             position_span: InnerSpan { start: 2, end: 2 },
             format: fmtdflt(),
-        })],
+        }))],
     );
 }
 #[test]
 fn format_position() {
     same(
         "{3}",
-        &[NextArgument(Argument {
+        &[NextArgument(Box::new(Argument {
             position: ArgumentIs(3),
             position_span: InnerSpan { start: 2, end: 3 },
             format: fmtdflt(),
-        })],
+        }))],
     );
 }
 #[test]
 fn format_position_nothing_else() {
     same(
         "{3:}",
-        &[NextArgument(Argument {
+        &[NextArgument(Box::new(Argument {
             position: ArgumentIs(3),
             position_span: InnerSpan { start: 2, end: 3 },
             format: fmtdflt(),
-        })],
+        }))],
     );
 }
 #[test]
 fn format_named() {
     same(
         "{name}",
-        &[NextArgument(Argument {
+        &[NextArgument(Box::new(Argument {
             position: ArgumentNamed("name"),
             position_span: InnerSpan { start: 2, end: 6 },
             format: fmtdflt(),
-        })],
+        }))],
     )
 }
 #[test]
 fn format_type() {
     same(
         "{3:x}",
-        &[NextArgument(Argument {
+        &[NextArgument(Box::new(Argument {
             position: ArgumentIs(3),
             position_span: InnerSpan { start: 2, end: 3 },
             format: FormatSpec {
@@ -134,14 +134,14 @@ fn format_type() {
                 ty: "x",
                 ty_span: None,
             },
-        })],
+        }))],
     );
 }
 #[test]
 fn format_align_fill() {
     same(
         "{3:>}",
-        &[NextArgument(Argument {
+        &[NextArgument(Box::new(Argument {
             position: ArgumentIs(3),
             position_span: InnerSpan { start: 2, end: 3 },
             format: FormatSpec {
@@ -155,11 +155,11 @@ fn format_align_fill() {
                 ty: "",
                 ty_span: None,
             },
-        })],
+        }))],
     );
     same(
         "{3:0<}",
-        &[NextArgument(Argument {
+        &[NextArgument(Box::new(Argument {
             position: ArgumentIs(3),
             position_span: InnerSpan { start: 2, end: 3 },
             format: FormatSpec {
@@ -173,11 +173,11 @@ fn format_align_fill() {
                 ty: "",
                 ty_span: None,
             },
-        })],
+        }))],
     );
     same(
         "{3:*<abcd}",
-        &[NextArgument(Argument {
+        &[NextArgument(Box::new(Argument {
             position: ArgumentIs(3),
             position_span: InnerSpan { start: 2, end: 3 },
             format: FormatSpec {
@@ -191,14 +191,14 @@ fn format_align_fill() {
                 ty: "abcd",
                 ty_span: Some(InnerSpan::new(6, 10)),
             },
-        })],
+        }))],
     );
 }
 #[test]
 fn format_counts() {
     same(
         "{:10x}",
-        &[NextArgument(Argument {
+        &[NextArgument(Box::new(Argument {
             position: ArgumentImplicitlyIs(0),
             position_span: InnerSpan { start: 2, end: 2 },
             format: FormatSpec {
@@ -212,11 +212,11 @@ fn format_counts() {
                 ty: "x",
                 ty_span: None,
             },
-        })],
+        }))],
     );
     same(
         "{:10$.10x}",
-        &[NextArgument(Argument {
+        &[NextArgument(Box::new(Argument {
             position: ArgumentImplicitlyIs(0),
             position_span: InnerSpan { start: 2, end: 2 },
             format: FormatSpec {
@@ -230,11 +230,11 @@ fn format_counts() {
                 ty: "x",
                 ty_span: None,
             },
-        })],
+        }))],
     );
     same(
         "{1:0$.10x}",
-        &[NextArgument(Argument {
+        &[NextArgument(Box::new(Argument {
             position: ArgumentIs(1),
             position_span: InnerSpan { start: 2, end: 3 },
             format: FormatSpec {
@@ -248,11 +248,11 @@ fn format_counts() {
                 ty: "x",
                 ty_span: None,
             },
-        })],
+        }))],
     );
     same(
         "{:.*x}",
-        &[NextArgument(Argument {
+        &[NextArgument(Box::new(Argument {
             position: ArgumentImplicitlyIs(1),
             position_span: InnerSpan { start: 2, end: 2 },
             format: FormatSpec {
@@ -266,11 +266,11 @@ fn format_counts() {
                 ty: "x",
                 ty_span: None,
             },
-        })],
+        }))],
     );
     same(
         "{:.10$x}",
-        &[NextArgument(Argument {
+        &[NextArgument(Box::new(Argument {
             position: ArgumentImplicitlyIs(0),
             position_span: InnerSpan { start: 2, end: 2 },
             format: FormatSpec {
@@ -284,11 +284,11 @@ fn format_counts() {
                 ty: "x",
                 ty_span: None,
             },
-        })],
+        }))],
     );
     same(
         "{:a$.b$?}",
-        &[NextArgument(Argument {
+        &[NextArgument(Box::new(Argument {
             position: ArgumentImplicitlyIs(0),
             position_span: InnerSpan { start: 2, end: 2 },
             format: FormatSpec {
@@ -302,11 +302,11 @@ fn format_counts() {
                 ty: "?",
                 ty_span: None,
             },
-        })],
+        }))],
     );
     same(
         "{:.4}",
-        &[NextArgument(Argument {
+        &[NextArgument(Box::new(Argument {
             position: ArgumentImplicitlyIs(0),
             position_span: InnerSpan { start: 2, end: 2 },
             format: FormatSpec {
@@ -320,14 +320,14 @@ fn format_counts() {
                 ty: "",
                 ty_span: None,
             },
-        })],
+        }))],
     )
 }
 #[test]
 fn format_flags() {
     same(
         "{:-}",
-        &[NextArgument(Argument {
+        &[NextArgument(Box::new(Argument {
             position: ArgumentImplicitlyIs(0),
             position_span: InnerSpan { start: 2, end: 2 },
             format: FormatSpec {
@@ -341,11 +341,11 @@ fn format_flags() {
                 ty: "",
                 ty_span: None,
             },
-        })],
+        }))],
     );
     same(
         "{:+#}",
-        &[NextArgument(Argument {
+        &[NextArgument(Box::new(Argument {
             position: ArgumentImplicitlyIs(0),
             position_span: InnerSpan { start: 2, end: 2 },
             format: FormatSpec {
@@ -359,7 +359,7 @@ fn format_flags() {
                 ty: "",
                 ty_span: None,
             },
-        })],
+        }))],
     );
 }
 #[test]
@@ -368,7 +368,7 @@ fn format_mixture() {
         "abcd {3:x} efg",
         &[
             String("abcd "),
-            NextArgument(Argument {
+            NextArgument(Box::new(Argument {
                 position: ArgumentIs(3),
                 position_span: InnerSpan { start: 7, end: 8 },
                 format: FormatSpec {
@@ -382,7 +382,7 @@ fn format_mixture() {
                     ty: "x",
                     ty_span: None,
                 },
-            }),
+            })),
             String(" efg"),
         ],
     );
@@ -391,18 +391,18 @@ fn format_mixture() {
 fn format_whitespace() {
     same(
         "{ }",
-        &[NextArgument(Argument {
+        &[NextArgument(Box::new(Argument {
             position: ArgumentImplicitlyIs(0),
             position_span: InnerSpan { start: 2, end: 3 },
             format: fmtdflt(),
-        })],
+        }))],
     );
     same(
         "{  }",
-        &[NextArgument(Argument {
+        &[NextArgument(Box::new(Argument {
             position: ArgumentImplicitlyIs(0),
             position_span: InnerSpan { start: 2, end: 4 },
             format: fmtdflt(),
-        })],
+        }))],
     );
 }