Auto merge of #120227 - nnethercote:further-improve-space_between, r=…

…petrochenkov Further improve `space_between` `space_between` is used by `print_tts` to decide when spaces should be put between tokens. This PR improves it in two ways: - avoid unnecessary spaces before semicolons, and - don't omit some necessary spaces before/after some punctuation symbols. r? `@petrochenkov`
rust-lang · Jan 31, 2024 · 80deabd · 80deabd
2 parents cb4d9a1 + 1fbabee
commit 80deabd
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Showing 28 changed files with 102 additions and 109 deletions.
diff --git a/compiler/rustc_ast_pretty/src/pprust/state.rs b/compiler/rustc_ast_pretty/src/pprust/state.rs
@@ -160,31 +160,46 @@ fn space_between(tt1: &TokenTree, tt2: &TokenTree) -> bool {
     use TokenTree::Delimited as Del;
     use TokenTree::Token as Tok;
 
+    fn is_punct(tt: &TokenTree) -> bool {
+        matches!(tt, TokenTree::Token(tok, _) if tok.is_punct())
+    }
+
     // Each match arm has one or more examples in comments. The default is to
     // insert space between adjacent tokens, except for the cases listed in
     // this match.
     match (tt1, tt2) {
         // No space after line doc comments.
         (Tok(Token { kind: DocComment(CommentKind::Line, ..), .. }, _), _) => false,
 
-        // `.` + ANYTHING: `x.y`, `tup.0`
-        // `$` + ANYTHING: `$e`
-        (Tok(Token { kind: Dot | Dollar, .. }, _), _) => false,
-
-        // ANYTHING + `,`: `foo,`
-        // ANYTHING + `.`: `x.y`, `tup.0`
-        // ANYTHING + `!`: `foo! { ... }`
-        //
-        // FIXME: Incorrect cases:
-        // - Logical not: `x =! y`, `if! x { f(); }`
-        // - Never type: `Fn() ->!`
-        (_, Tok(Token { kind: Comma | Dot | Not, .. }, _)) => false,
-
-        // IDENT + `(`: `f(3)`
-        //
-        // FIXME: Incorrect cases:
-        // - Let: `let(a, b) = (1, 2)`
-        (Tok(Token { kind: Ident(..), .. }, _), Del(_, _, Parenthesis, _)) => false,
+        // `.` + NON-PUNCT: `x.y`, `tup.0`
+        (Tok(Token { kind: Dot, .. }, _), tt2) if !is_punct(tt2) => false,
+
+        // `$` + IDENT: `$e`
+        (Tok(Token { kind: Dollar, .. }, _), Tok(Token { kind: Ident(..), .. }, _)) => false,
+
+        // NON-PUNCT + `,`: `foo,`
+        // NON-PUNCT + `;`: `x = 3;`, `[T; 3]`
+        // NON-PUNCT + `.`: `x.y`, `tup.0`
+        (tt1, Tok(Token { kind: Comma | Semi | Dot, .. }, _)) if !is_punct(tt1) => false,
+
+        // IDENT + `!`: `println!()`, but `if !x { ... }` needs a space after the `if`
+        (Tok(Token { kind: Ident(sym, is_raw), span }, _), Tok(Token { kind: Not, .. }, _))
+            if !Ident::new(*sym, *span).is_reserved() || *is_raw =>
+        {
+            false
+        }
+
+        // IDENT|`fn`|`Self`|`pub` + `(`: `f(3)`, `fn(x: u8)`, `Self()`, `pub(crate)`,
+        //      but `let (a, b) = (1, 2)` needs a space after the `let`
+        (Tok(Token { kind: Ident(sym, is_raw), span }, _), Del(_, _, Parenthesis, _))
+            if !Ident::new(*sym, *span).is_reserved()
+                || *sym == kw::Fn
+                || *sym == kw::SelfUpper
+                || *sym == kw::Pub
+                || *is_raw =>
+        {
+            false
+        }
 
         // `#` + `[`: `#[attr]`
         (Tok(Token { kind: Pound, .. }, _), Del(_, _, Bracket, _)) => false,

diff --git a/tests/pretty/delimited-token-groups.rs b/tests/pretty/delimited-token-groups.rs
@@ -9,7 +9,7 @@ mac! {
     {
         fn clone() -> S
         {
-            panic! () ;
+            panic! ();
 
         }
     }

diff --git a/tests/pretty/macro_rules.rs b/tests/pretty/macro_rules.rs
@@ -1,19 +1,19 @@
 // pp-exact
 
-macro_rules! brace { () => {} ; }
+macro_rules! brace { () => {}; }
 
-macro_rules! bracket[() => {} ;];
+macro_rules! bracket[() => {};];
 
-macro_rules! paren(() => {} ;);
+macro_rules! paren(() => {};);
 
 macro_rules! matcher_brackets {
-    (paren) => {} ; (bracket) => {} ; (brace) => {} ;
+    (paren) => {}; (bracket) => {}; (brace) => {};
 }
 
 macro_rules! all_fragments {
     ($b : block, $e : expr, $i : ident, $it : item, $l : lifetime, $lit :
     literal, $m : meta, $p : pat, $pth : path, $s : stmt, $tt : tt, $ty : ty,
-    $vis : vis) => {} ;
+    $vis : vis) => {};
 }
 
 fn main() {}
diff --git a/tests/pretty/stmt_expr_attributes.rs b/tests/pretty/stmt_expr_attributes.rs
@@ -113,7 +113,7 @@ fn _8() {
 }
 
 fn _9() {
-    macro_rules! stmt_mac { () => { let _ = () ; } }
+    macro_rules! stmt_mac { () => { let _ = (); } }
 
     #[rustc_dummy]
     stmt_mac!();

diff --git a/tests/ui/macros/stringify.rs b/tests/ui/macros/stringify.rs
@@ -107,9 +107,9 @@ fn test_expr() {
     c1!(expr, [ true || false ], "true || false");
     c1!(expr, [ true || false && false ], "true || false && false");
     c1!(expr, [ a < 1 && 2 < b && c > 3 && 4 > d ], "a < 1 && 2 < b && c > 3 && 4 > d");
-    c2!(expr, [ a & b & !c ], "a & b & !c", "a & b &!c"); // FIXME
+    c1!(expr, [ a & b & !c ], "a & b & !c");
     c1!(expr, [ a + b * c - d + -1 * -2 - -3], "a + b * c - d + -1 * -2 - -3");
-    c2!(expr, [ x = !y ], "x = !y", "x =!y"); // FIXME
+    c1!(expr, [ x = !y ], "x = !y");
 
     // ExprKind::Unary
     c1!(expr, [ *expr ], "*expr");
@@ -141,15 +141,14 @@ fn test_expr() {
         "if let _ = (true && false) {}",
         "if let _ = true && false {}",
     );
-    c2!(expr,
+    c1!(expr,
         [ match () { _ if let _ = Struct {} => {} } ],
-        "match () { _ if let _ = Struct {} => {} }",
-        "match() { _ if let _ = Struct {} => {} }",
+        "match () { _ if let _ = Struct {} => {} }"
     );
 
     // ExprKind::If
     c1!(expr, [ if true {} ], "if true {}");
-    c2!(expr, [ if !true {} ], "if !true {}", "if!true {}"); // FIXME
+    c1!(expr, [ if !true {} ], "if !true {}");
     c1!(expr, [ if ::std::blah() { } else { } ], "if ::std::blah() {} else {}");
     c1!(expr, [ if let true = true {} else {} ], "if let true = true {} else {}");
     c1!(expr,
@@ -212,7 +211,7 @@ fn test_expr() {
     c2_match_arm!(
         [ { 1 } - 1 ],
         "match () { _ => ({ 1 }) - 1, }",
-        "match() { _ => { 1 } - 1 }",
+        "match () { _ => { 1 } - 1 }",
     );
 
     // ExprKind::Closure
@@ -655,11 +654,11 @@ fn test_stmt() {
     c2!(stmt, [ let _ ], "let _;", "let _");
     c2!(stmt, [ let x = true ], "let x = true;", "let x = true");
     c2!(stmt, [ let x: bool = true ], "let x: bool = true;", "let x: bool = true");
-    c2!(stmt, [ let (a, b) = (1, 2) ], "let (a, b) = (1, 2);", "let(a, b) = (1, 2)"); // FIXME
+    c2!(stmt, [ let (a, b) = (1, 2) ], "let (a, b) = (1, 2);", "let (a, b) = (1, 2)");
     c2!(stmt,
         [ let (a, b): (u32, u32) = (1, 2) ],
         "let (a, b): (u32, u32) = (1, 2);",
-        "let(a, b): (u32, u32) = (1, 2)" // FIXME
+        "let (a, b): (u32, u32) = (1, 2)"
     );
     macro_rules! c2_let_expr_minus_one {
         ([ $expr:expr ], $stmt_expected:expr, $tokens_expected:expr $(,)?) => {
@@ -776,8 +775,8 @@ fn test_ty() {
     c1!(ty, [ Ref<'a> ], "Ref<'a>");
     c1!(ty, [ PhantomData<T> ], "PhantomData<T>");
     c2!(ty, [ PhantomData::<T> ], "PhantomData<T>", "PhantomData::<T>");
-    c2!(ty, [ Fn() -> ! ], "Fn() -> !", "Fn() ->!");
-    c2!(ty, [ Fn(u8) -> ! ], "Fn(u8) -> !", "Fn(u8) ->!"); // FIXME
+    c1!(ty, [ Fn() -> ! ], "Fn() -> !");
+    c1!(ty, [ Fn(u8) -> ! ], "Fn(u8) -> !");
     c1!(ty, [ <Struct as Trait>::Type ], "<Struct as Trait>::Type");
 
     // TyKind::TraitObject
@@ -857,16 +856,16 @@ fn test_punct() {
     // Otherwise, any old proc macro that parses pretty-printed code might glue
     // together tokens that shouldn't be glued.
     p!([ = = < < <= <= == == != != >= >= > > ], "= = < < <= <= == == != != >= >= > >");
-    p!([ && && & & || || | | ! ! ], "&& && & & || || | |!!"); // FIXME
+    p!([ && && & & || || | | ! ! ], "&& && & & || || | | ! !");
     p!([ ~ ~ @ @ # # ], "~ ~ @ @ # #");
-    p!([ . . .. .. ... ... ..= ..=], ".... .. ... ... ..= ..="); // FIXME
-    p!([ , , ; ; : : :: :: ], ",, ; ; : : :: ::"); // FIXME
+    p!([ . . .. .. ... ... ..= ..=], ". . .. .. ... ... ..= ..=");
+    p!([ , , ; ; : : :: :: ], ", , ; ; : : :: ::");
     p!([ -> -> <- <- => =>], "-> -> <- <- => =>");
-    p!([ $ $ ? ? ' ' ], "$$? ? ' '"); // FIXME
+    p!([ $ $ ? ? ' ' ], "$ $ ? ? ' '");
     p!([ + + += += - - -= -= * * *= *= / / /= /= ], "+ + += += - - -= -= * * *= *= / / /= /=");
     p!([ % % %= %= ^ ^ ^= ^= << << <<= <<= >> >> >>= >>= ],
         "% % %= %= ^ ^ ^= ^= << << <<= <<= >> >> >>= >>=");
-    p!([ +! ?= |> >>@ --> <-- $$ =====> ], "+! ?= |> >>@ --> <-- $$=====>");
-    p!([ ,; ;, ** @@ $+$ >< <> ?? +== ], ",; ;, ** @@ $+$>< <> ?? +=="); // FIXME: `$ >` -> `$>`
+    p!([ +! ?= |> >>@ --> <-- $$ =====> ], "+! ?= |> >>@ --> <-- $$ =====>");
+    p!([ ,; ;, ** @@ $+$ >< <> ?? +== ], ",; ;, ** @@ $+$ >< <> ?? +==");
     p!([ :#!@|$=&*,+;*~? ], ":#!@|$=&*,+;*~?");
 }
diff --git a/tests/ui/macros/trace_faulty_macros.stderr b/tests/ui/macros/trace_faulty_macros.stderr
@@ -111,7 +111,7 @@ LL |     test!(let x = 1+1);
    = note: expanding `test! { let x = 1+1 }`
    = note: to `test! ((x, 1 + 1))`
    = note: expanding `test! { (x, 1 + 1) }`
-   = note: to `let x = 1 + 1 ;`
+   = note: to `let x = 1 + 1;`
 
 error: aborting due to 5 previous errors
 

diff --git a/tests/ui/proc-macro/allowed-attr-stmt-expr.stdout b/tests/ui/proc-macro/allowed-attr-stmt-expr.stdout
@@ -1,5 +1,4 @@
 PRINT-ATTR INPUT (DISPLAY): struct ItemWithSemi;
-PRINT-ATTR RE-COLLECTED (DISPLAY): struct ItemWithSemi ;
 PRINT-ATTR INPUT (DEBUG): TokenStream [
     Ident {
         ident: "struct",
@@ -47,7 +46,6 @@ PRINT-ATTR INPUT (DEBUG): TokenStream [
     },
 ]
 PRINT-ATTR INPUT (DISPLAY): #[expect_let] let string = "Hello, world!";
-PRINT-ATTR RE-COLLECTED (DISPLAY): #[expect_let] let string = "Hello, world!" ;
 PRINT-ATTR INPUT (DEBUG): TokenStream [
     Punct {
         ch: '#',
@@ -90,7 +88,7 @@ PRINT-ATTR INPUT (DEBUG): TokenStream [
     },
 ]
 PRINT-ATTR INPUT (DISPLAY): #[expect_my_macro_stmt] my_macro!("{}", string);
-PRINT-ATTR RE-COLLECTED (DISPLAY): #[expect_my_macro_stmt] my_macro! ("{}", string) ;
+PRINT-ATTR RE-COLLECTED (DISPLAY): #[expect_my_macro_stmt] my_macro! ("{}", string);
 PRINT-ATTR INPUT (DEBUG): TokenStream [
     Punct {
         ch: '#',
@@ -144,7 +142,7 @@ PRINT-ATTR INPUT (DEBUG): TokenStream [
     },
 ]
 PRINT-ATTR INPUT (DISPLAY): second_make_stmt!(#[allow(dead_code)] struct Bar {});
-PRINT-ATTR RE-COLLECTED (DISPLAY): second_make_stmt! (#[allow(dead_code)] struct Bar {}) ;
+PRINT-ATTR RE-COLLECTED (DISPLAY): second_make_stmt! (#[allow(dead_code)] struct Bar {});
 PRINT-ATTR INPUT (DEBUG): TokenStream [
     Ident {
         ident: "second_make_stmt",
@@ -293,7 +291,6 @@ PRINT-ATTR INPUT (DEBUG): TokenStream [
     },
 ]
 PRINT-ATTR INPUT (DISPLAY): #[rustc_dummy] struct NonBracedStruct;
-PRINT-ATTR RE-COLLECTED (DISPLAY): #[rustc_dummy] struct NonBracedStruct ;
 PRINT-ATTR INPUT (DEBUG): TokenStream [
     Punct {
         ch: '#',

diff --git a/tests/ui/proc-macro/attr-stmt-expr.stdout b/tests/ui/proc-macro/attr-stmt-expr.stdout
@@ -30,7 +30,6 @@ PRINT-ATTR INPUT (DEBUG): TokenStream [
     },
 ]
 PRINT-ATTR INPUT (DISPLAY): #[expect_let] let string = "Hello, world!";
-PRINT-ATTR RE-COLLECTED (DISPLAY): #[expect_let] let string = "Hello, world!" ;
 PRINT-ATTR INPUT (DEBUG): TokenStream [
     Punct {
         ch: '#',
@@ -73,7 +72,7 @@ PRINT-ATTR INPUT (DEBUG): TokenStream [
     },
 ]
 PRINT-ATTR INPUT (DISPLAY): #[expect_my_macro_stmt] my_macro!("{}", string);
-PRINT-ATTR RE-COLLECTED (DISPLAY): #[expect_my_macro_stmt] my_macro! ("{}", string) ;
+PRINT-ATTR RE-COLLECTED (DISPLAY): #[expect_my_macro_stmt] my_macro! ("{}", string);
 PRINT-ATTR INPUT (DEBUG): TokenStream [
     Punct {
         ch: '#',
@@ -127,7 +126,7 @@ PRINT-ATTR INPUT (DEBUG): TokenStream [
     },
 ]
 PRINT-ATTR INPUT (DISPLAY): second_make_stmt!(#[allow(dead_code)] struct Bar {});
-PRINT-ATTR RE-COLLECTED (DISPLAY): second_make_stmt! (#[allow(dead_code)] struct Bar {}) ;
+PRINT-ATTR RE-COLLECTED (DISPLAY): second_make_stmt! (#[allow(dead_code)] struct Bar {});
 PRINT-ATTR INPUT (DEBUG): TokenStream [
     Ident {
         ident: "second_make_stmt",

diff --git a/tests/ui/proc-macro/attribute-spans-preserved.stdout b/tests/ui/proc-macro/attribute-spans-preserved.stdout
@@ -1 +1 @@
-fn main() { let y : u32 = "z" ; { let x: u32 = "y"; } }
+fn main() { let y : u32 = "z"; { let x: u32 = "y"; } }
diff --git a/tests/ui/proc-macro/auxiliary/attr-stmt-expr.rs b/tests/ui/proc-macro/auxiliary/attr-stmt-expr.rs
@@ -10,14 +10,14 @@ use proc_macro::TokenStream;
 #[proc_macro_attribute]
 pub fn expect_let(attr: TokenStream, item: TokenStream) -> TokenStream {
     assert!(attr.to_string().is_empty());
-    assert_eq!(item.to_string(), "let string = \"Hello, world!\" ;");
+    assert_eq!(item.to_string(), "let string = \"Hello, world!\";");
     item
 }
 
 #[proc_macro_attribute]
 pub fn expect_my_macro_stmt(attr: TokenStream, item: TokenStream) -> TokenStream {
     assert!(attr.to_string().is_empty());
-    assert_eq!(item.to_string(), "my_macro! (\"{}\", string) ;");
+    assert_eq!(item.to_string(), "my_macro! (\"{}\", string);");
     item
 }
 

diff --git a/tests/ui/proc-macro/cfg-eval-inner.stdout b/tests/ui/proc-macro/cfg-eval-inner.stdout
@@ -11,10 +11,10 @@ PRINT-ATTR RE-COLLECTED (DISPLAY): impl Foo <
     { field: [u8; { #![rustc_dummy(another_cursed_inner)] 1 }] } 0
 }] > { #![rustc_dummy(evaluated_attr)] fn bar() {} }
 PRINT-ATTR DEEP-RE-COLLECTED (DISPLAY): impl Foo <
-[u8 ;
+[u8;
 {
     #! [rustc_dummy(cursed_inner)] #! [allow(unused)] struct Inner
-    { field : [u8 ; { #! [rustc_dummy(another_cursed_inner)] 1 }] } 0
+    { field : [u8; { #! [rustc_dummy(another_cursed_inner)] 1 }] } 0
 }] > { #! [rustc_dummy(evaluated_attr)] fn bar() {} }
 PRINT-ATTR INPUT (DEBUG): TokenStream [
     Ident {

diff --git a/tests/ui/proc-macro/doc-comment-preserved.stdout b/tests/ui/proc-macro/doc-comment-preserved.stdout
@@ -6,7 +6,7 @@ PRINT-BANG INPUT (DISPLAY): /**
 *******
 */
  pub struct S;
-PRINT-BANG RE-COLLECTED (DISPLAY): #[doc = "\n*******\n* DOC *\n* DOC *\n* DOC *\n*******\n"] pub struct S ;
+PRINT-BANG RE-COLLECTED (DISPLAY): #[doc = "\n*******\n* DOC *\n* DOC *\n* DOC *\n*******\n"] pub struct S;
 PRINT-BANG INPUT (DEBUG): TokenStream [
     Punct {
         ch: '#',

diff --git a/tests/ui/proc-macro/dollar-crate-issue-57089.stdout b/tests/ui/proc-macro/dollar-crate-issue-57089.stdout
@@ -1,5 +1,4 @@
 PRINT-BANG INPUT (DISPLAY): struct M($crate :: S);
-PRINT-BANG RE-COLLECTED (DISPLAY): struct M($crate :: S) ;
 PRINT-BANG INPUT (DEBUG): TokenStream [
     Ident {
         ident: "struct",
@@ -40,7 +39,6 @@ PRINT-BANG INPUT (DEBUG): TokenStream [
     },
 ]
 PRINT-ATTR INPUT (DISPLAY): struct A($crate :: S);
-PRINT-ATTR RE-COLLECTED (DISPLAY): struct A($crate :: S) ;
 PRINT-ATTR INPUT (DEBUG): TokenStream [
     Ident {
         ident: "struct",

diff --git a/tests/ui/proc-macro/dollar-crate-issue-62325.stdout b/tests/ui/proc-macro/dollar-crate-issue-62325.stdout
@@ -1,5 +1,4 @@
 PRINT-ATTR INPUT (DISPLAY): struct A(identity! ($crate :: S));
-PRINT-ATTR RE-COLLECTED (DISPLAY): struct A(identity! ($crate :: S)) ;
 PRINT-ATTR INPUT (DEBUG): TokenStream [
     Ident {
         ident: "struct",
@@ -55,7 +54,6 @@ PRINT-ATTR INPUT (DEBUG): TokenStream [
     },
 ]
 PRINT-ATTR INPUT (DISPLAY): struct B(identity! ($crate :: S));
-PRINT-ATTR RE-COLLECTED (DISPLAY): struct B(identity! ($crate :: S)) ;
 PRINT-ATTR INPUT (DEBUG): TokenStream [
     Ident {
         ident: "struct",

diff --git a/tests/ui/proc-macro/dollar-crate.stdout b/tests/ui/proc-macro/dollar-crate.stdout
@@ -1,5 +1,4 @@
 PRINT-BANG INPUT (DISPLAY): struct M($crate :: S);
-PRINT-BANG RE-COLLECTED (DISPLAY): struct M($crate :: S) ;
 PRINT-BANG INPUT (DEBUG): TokenStream [
     Ident {
         ident: "struct",
@@ -40,7 +39,6 @@ PRINT-BANG INPUT (DEBUG): TokenStream [
     },
 ]
 PRINT-ATTR INPUT (DISPLAY): struct A($crate :: S);
-PRINT-ATTR RE-COLLECTED (DISPLAY): struct A($crate :: S) ;
 PRINT-ATTR INPUT (DEBUG): TokenStream [
     Ident {
         ident: "struct",
@@ -81,7 +79,6 @@ PRINT-ATTR INPUT (DEBUG): TokenStream [
     },
 ]
 PRINT-DERIVE INPUT (DISPLAY): struct D($crate :: S);
-PRINT-DERIVE RE-COLLECTED (DISPLAY): struct D($crate :: S) ;
 PRINT-DERIVE INPUT (DEBUG): TokenStream [
     Ident {
         ident: "struct",
@@ -122,7 +119,6 @@ PRINT-DERIVE INPUT (DEBUG): TokenStream [
     },
 ]
 PRINT-BANG INPUT (DISPLAY): struct M($crate :: S);
-PRINT-BANG RE-COLLECTED (DISPLAY): struct M($crate :: S) ;
 PRINT-BANG INPUT (DEBUG): TokenStream [
     Ident {
         ident: "struct",
@@ -163,7 +159,6 @@ PRINT-BANG INPUT (DEBUG): TokenStream [
     },
 ]
 PRINT-ATTR INPUT (DISPLAY): struct A($crate :: S);
-PRINT-ATTR RE-COLLECTED (DISPLAY): struct A($crate :: S) ;
 PRINT-ATTR INPUT (DEBUG): TokenStream [
     Ident {
         ident: "struct",
@@ -204,7 +199,6 @@ PRINT-ATTR INPUT (DEBUG): TokenStream [
     },
 ]
 PRINT-DERIVE INPUT (DISPLAY): struct D($crate :: S);
-PRINT-DERIVE RE-COLLECTED (DISPLAY): struct D($crate :: S) ;
 PRINT-DERIVE INPUT (DEBUG): TokenStream [
     Ident {
         ident: "struct",