Migrate offset_of from a macro to builtin # syntax

est31 · est31 · commit 5eb29c7f49c2 · 2023-05-05T21:44:13.000+02:00
diff --git a/compiler/rustc_ast_pretty/src/pprust/state/expr.rs b/compiler/rustc_ast_pretty/src/pprust/state/expr.rs
@@ -556,8 +556,7 @@ impl<'a> State<'a> {
                 self.pclose();
             }
             ast::ExprKind::OffsetOf(container, fields) => {
-                // FIXME: This should have its own syntax, distinct from a macro invocation.
-                self.word("offset_of!");
+                self.word("builtin # offset_of");
                 self.popen();
                 self.rbox(0, Inconsistent);
                 self.print_type(container);
diff --git a/compiler/rustc_builtin_macros/messages.ftl b/compiler/rustc_builtin_macros/messages.ftl
@@ -150,10 +150,6 @@ builtin_macros_format_pos_mismatch = {$n} positional {$n ->
     *[more] arguments
     } in format string, but {$desc}
 
-builtin_macros_offset_of_expected_field = expected field
-
-builtin_macros_offset_of_expected_two_args = expected 2 arguments
-
 builtin_macros_test_case_non_item = `#[test_case]` attribute is only allowed on items
 
 builtin_macros_test_bad_fn = {$kind} functions cannot be used for tests
diff --git a/compiler/rustc_builtin_macros/src/lib.rs b/compiler/rustc_builtin_macros/src/lib.rs
@@ -44,7 +44,6 @@ mod format;
 mod format_foreign;
 mod global_allocator;
 mod log_syntax;
-mod offset_of;
 mod source_util;
 mod test;
 mod trace_macros;
@@ -92,7 +91,6 @@ pub fn register_builtin_macros(resolver: &mut dyn ResolverExpand) {
         line: source_util::expand_line,
         log_syntax: log_syntax::expand_log_syntax,
         module_path: source_util::expand_mod,
-        offset_of: offset_of::expand_offset_of,
         option_env: env::expand_option_env,
         core_panic: edition_panic::expand_panic,
         std_panic: edition_panic::expand_panic,
diff --git a/compiler/rustc_builtin_macros/src/offset_of.rs b/compiler/rustc_builtin_macros/src/offset_of.rs
diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
@@ -1759,7 +1759,11 @@ impl<'a> Parser<'a> {
 
     /// Parse `builtin # ident(args,*)`.
     fn parse_expr_builtin(&mut self) -> PResult<'a, P<Expr>> {
-        self.parse_builtin(|_this, _lo, _ident| {
+        self.parse_builtin(|this, lo, ident| {
+            if ident.name == sym::offset_of {
+                return Ok(Some(this.parse_expr_offset_of(lo)?));
+            }
+
             Ok(None)
         })
     }
@@ -1793,6 +1797,20 @@ impl<'a> Parser<'a> {
         ret
     }
 
+    pub(crate) fn parse_expr_offset_of(&mut self, lo: Span) -> PResult<'a, P<Expr>> {
+        let container = self.parse_ty()?;
+        self.expect(&TokenKind::Comma)?;
+
+        let seq_sep = SeqSep { sep: Some(token::Dot), trailing_sep_allowed: false };
+        let (fields, _trailing, _recovered) = self.parse_seq_to_before_end(
+            &TokenKind::CloseDelim(Delimiter::Parenthesis),
+            seq_sep,
+            Parser::parse_field_name,
+        )?;
+        let span = lo.to(self.token.span);
+        Ok(self.mk_expr(span, ExprKind::OffsetOf(container, fields.to_vec().into())))
+    }
+
     /// Returns a string literal if the next token is a string literal.
     /// In case of error returns `Some(lit)` if the next token is a literal with a wrong kind,
     /// and returns `None` if the next token is not literal at all.
diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
@@ -441,6 +441,7 @@ symbols! {
         breakpoint,
         bridge,
         bswap,
+        builtin_syntax,
         c_str,
         c_str_literals,
         c_unwind,
diff --git a/library/core/src/mem/mod.rs b/library/core/src/mem/mod.rs
@@ -1315,9 +1315,9 @@ impl<T> SizedTypeProperties for T {}
 ///
 /// assert_eq!(mem::offset_of!(NestedA, b.0), 0);
 /// ```
-#[unstable(feature = "offset_of", issue = "106655")]
-#[rustc_builtin_macro]
 #[cfg(not(bootstrap))]
+#[unstable(feature = "offset_of", issue = "106655")]
+#[allow_internal_unstable(builtin_syntax)]
 pub macro offset_of($Container:ty, $($fields:tt).+ $(,)?) {
-    /* compiler built-in */
+    builtin # offset_of($Container, $($fields).+)
 }
diff --git a/tests/mir-opt/const_prop/offset_of.concrete.ConstProp.diff b/tests/mir-opt/const_prop/offset_of.concrete.ConstProp.diff
@@ -22,17 +22,17 @@
   
       bb0: {
           StorageLive(_1);                 // scope 0 at $DIR/offset_of.rs:+1:9: +1:10
--         _1 = OffsetOf(Alpha, [0]);       // scope 0 at $DIR/offset_of.rs:+1:13: +1:33
-+         _1 = const 4_usize;              // scope 0 at $DIR/offset_of.rs:+1:13: +1:33
+-         _1 = OffsetOf(Alpha, [0]);       // scope 0 at $SRC_DIR/core/src/mem/mod.rs:LL:COL
++         _1 = const 4_usize;              // scope 0 at $SRC_DIR/core/src/mem/mod.rs:LL:COL
           StorageLive(_2);                 // scope 1 at $DIR/offset_of.rs:+2:9: +2:10
--         _2 = OffsetOf(Alpha, [1]);       // scope 1 at $DIR/offset_of.rs:+2:13: +2:33
-+         _2 = const 0_usize;              // scope 1 at $DIR/offset_of.rs:+2:13: +2:33
+-         _2 = OffsetOf(Alpha, [1]);       // scope 1 at $SRC_DIR/core/src/mem/mod.rs:LL:COL
++         _2 = const 0_usize;              // scope 1 at $SRC_DIR/core/src/mem/mod.rs:LL:COL
           StorageLive(_3);                 // scope 2 at $DIR/offset_of.rs:+3:9: +3:11
--         _3 = OffsetOf(Alpha, [2, 0]);    // scope 2 at $DIR/offset_of.rs:+3:14: +3:36
-+         _3 = const 2_usize;              // scope 2 at $DIR/offset_of.rs:+3:14: +3:36
+-         _3 = OffsetOf(Alpha, [2, 0]);    // scope 2 at $SRC_DIR/core/src/mem/mod.rs:LL:COL
++         _3 = const 2_usize;              // scope 2 at $SRC_DIR/core/src/mem/mod.rs:LL:COL
           StorageLive(_4);                 // scope 3 at $DIR/offset_of.rs:+4:9: +4:11
--         _4 = OffsetOf(Alpha, [2, 1]);    // scope 3 at $DIR/offset_of.rs:+4:14: +4:36
-+         _4 = const 3_usize;              // scope 3 at $DIR/offset_of.rs:+4:14: +4:36
+-         _4 = OffsetOf(Alpha, [2, 1]);    // scope 3 at $SRC_DIR/core/src/mem/mod.rs:LL:COL
++         _4 = const 3_usize;              // scope 3 at $SRC_DIR/core/src/mem/mod.rs:LL:COL
           _0 = const ();                   // scope 0 at $DIR/offset_of.rs:+0:15: +5:2
           StorageDead(_4);                 // scope 3 at $DIR/offset_of.rs:+5:1: +5:2
           StorageDead(_3);                 // scope 2 at $DIR/offset_of.rs:+5:1: +5:2
diff --git a/tests/mir-opt/const_prop/offset_of.generic.ConstProp.diff b/tests/mir-opt/const_prop/offset_of.generic.ConstProp.diff
@@ -22,13 +22,13 @@
   
       bb0: {
           StorageLive(_1);                 // scope 0 at $DIR/offset_of.rs:+1:9: +1:11
-          _1 = OffsetOf(Gamma<T>, [0]);    // scope 0 at $DIR/offset_of.rs:+1:14: +1:37
+          _1 = OffsetOf(Gamma<T>, [0]);    // scope 0 at $SRC_DIR/core/src/mem/mod.rs:LL:COL
           StorageLive(_2);                 // scope 1 at $DIR/offset_of.rs:+2:9: +2:11
-          _2 = OffsetOf(Gamma<T>, [1]);    // scope 1 at $DIR/offset_of.rs:+2:14: +2:37
+          _2 = OffsetOf(Gamma<T>, [1]);    // scope 1 at $SRC_DIR/core/src/mem/mod.rs:LL:COL
           StorageLive(_3);                 // scope 2 at $DIR/offset_of.rs:+3:9: +3:11
-          _3 = OffsetOf(Delta<T>, [1]);    // scope 2 at $DIR/offset_of.rs:+3:14: +3:37
+          _3 = OffsetOf(Delta<T>, [1]);    // scope 2 at $SRC_DIR/core/src/mem/mod.rs:LL:COL
           StorageLive(_4);                 // scope 3 at $DIR/offset_of.rs:+4:9: +4:11
-          _4 = OffsetOf(Delta<T>, [2]);    // scope 3 at $DIR/offset_of.rs:+4:14: +4:37
+          _4 = OffsetOf(Delta<T>, [2]);    // scope 3 at $SRC_DIR/core/src/mem/mod.rs:LL:COL
           _0 = const ();                   // scope 0 at $DIR/offset_of.rs:+0:17: +5:2
           StorageDead(_4);                 // scope 3 at $DIR/offset_of.rs:+5:1: +5:2
           StorageDead(_3);                 // scope 2 at $DIR/offset_of.rs:+5:1: +5:2
diff --git a/tests/ui/offset-of/offset-of-arg-count.rs b/tests/ui/offset-of/offset-of-arg-count.rs
@@ -3,7 +3,15 @@
 use std::mem::offset_of;
 
 fn main() {
-    offset_of!(NotEnoughArguments); //~ ERROR expected one of
-    offset_of!(NotEnoughArgumentsWithAComma, ); //~ ERROR expected 2 arguments
-    offset_of!(Container, field, too many arguments); //~ ERROR expected 2 arguments
+    offset_of!(NotEnoughArguments); //~ ERROR unexpected end of macro invocation
+    offset_of!(NotEnoughArgumentsWithAComma, ); //~ ERROR unexpected end of macro invocation
+    offset_of!(Container, field, too many arguments); //~ ERROR no rules expected the token `too`
+    offset_of!(S, f); // compiles fine
+    offset_of!(S, f,); // also compiles fine
+    offset_of!(S, f.); //~ ERROR unexpected end of macro invocation
+    offset_of!(S, f.,); //~ ERROR expected identifier
+    offset_of!(S, f..); //~ ERROR no rules expected the token
+    offset_of!(S, f..,); //~ ERROR no rules expected the token
 }
+
+struct S { f: u8, }
diff --git a/tests/ui/offset-of/offset-of-arg-count.stderr b/tests/ui/offset-of/offset-of-arg-count.stderr
@@ -1,20 +1,59 @@
-error: expected one of `!`, `(`, `+`, `,`, `::`, or `<`, found `<eof>`
-  --> $DIR/offset-of-arg-count.rs:6:16
+error: unexpected end of macro invocation
+  --> $DIR/offset-of-arg-count.rs:6:34
    |
 LL |     offset_of!(NotEnoughArguments);
-   |                ^^^^^^^^^^^^^^^^^^ expected one of `!`, `(`, `+`, `,`, `::`, or `<`
+   |                                  ^ missing tokens in macro arguments
+   |
+note: while trying to match `,`
+  --> $SRC_DIR/core/src/mem/mod.rs:LL:COL
 
-error: expected 2 arguments
-  --> $DIR/offset-of-arg-count.rs:7:5
+error: unexpected end of macro invocation
+  --> $DIR/offset-of-arg-count.rs:7:45
    |
 LL |     offset_of!(NotEnoughArgumentsWithAComma, );
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |                                             ^ missing tokens in macro arguments
+   |
+note: while trying to match meta-variable `$fields:tt`
+  --> $SRC_DIR/core/src/mem/mod.rs:LL:COL
 
-error: expected 2 arguments
-  --> $DIR/offset-of-arg-count.rs:8:5
+error: no rules expected the token `too`
+  --> $DIR/offset-of-arg-count.rs:8:34
    |
 LL |     offset_of!(Container, field, too many arguments);
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |                                  ^^^ no rules expected this token in macro call
+   |
+   = note: while trying to match sequence end
+
+error: unexpected end of macro invocation
+  --> $DIR/offset-of-arg-count.rs:11:21
+   |
+LL |     offset_of!(S, f.);
+   |                     ^ missing tokens in macro arguments
+   |
+note: while trying to match meta-variable `$fields:tt`
+  --> $SRC_DIR/core/src/mem/mod.rs:LL:COL
+
+error: expected identifier, found `,`
+  --> $DIR/offset-of-arg-count.rs:12:21
+   |
+LL |     offset_of!(S, f.,);
+   |                     ^ expected identifier
+
+error: no rules expected the token `..`
+  --> $DIR/offset-of-arg-count.rs:13:20
+   |
+LL |     offset_of!(S, f..);
+   |                    ^^ no rules expected this token in macro call
+   |
+   = note: while trying to match sequence start
+
+error: no rules expected the token `..`
+  --> $DIR/offset-of-arg-count.rs:14:20
+   |
+LL |     offset_of!(S, f..,);
+   |                    ^^ no rules expected this token in macro call
+   |
+   = note: while trying to match sequence start
 
-error: aborting due to 3 previous errors
+error: aborting due to 7 previous errors
 
diff --git a/tests/ui/offset-of/offset-of-builtin.rs b/tests/ui/offset-of/offset-of-builtin.rs
@@ -0,0 +1,44 @@
+// For the exposed macro we already test these errors in the other files,
+// but this test helps to make sure the builtin construct also errors.
+// This has the same examples as offset-of-arg-count.rs
+
+
+
+fn main() {
+    builtin # offset_of(NotEnoughArguments); //~ ERROR expected one of
+}
+fn t1() {
+    // Already errored upon at the macro level. Yielding an error would require
+    // extra effort.
+    builtin # offset_of(NotEnoughArgumentsWithAComma, );
+}
+fn t2() {
+    builtin # offset_of(Container, field, too many arguments); //~ ERROR expected identifier, found
+    //~| ERROR found `,`
+    //~| ERROR found `many`
+    //~| ERROR found `arguments`
+}
+fn t3() {
+    builtin # offset_of(S, f); // compiles fine
+}
+fn t4() {
+    // Already errored upon at the macro level. Yielding an error would require
+    // extra effort.
+    builtin # offset_of(S, f);
+}
+fn t5() {
+    builtin # offset_of(S, f.); //~ ERROR expected identifier
+}
+fn t6() {
+    builtin # offset_of(S, f.,); //~ ERROR expected identifier
+}
+fn t7() {
+    builtin # offset_of(S, f..); //~ ERROR expected one of
+}
+fn t8() {
+    // Already errored upon at the macro level. Yielding an error would require
+    // extra effort.
+    builtin # offset_of(S, f..,);
+}
+
+struct S { f: u8, }
diff --git a/tests/ui/offset-of/offset-of-builtin.stderr b/tests/ui/offset-of/offset-of-builtin.stderr
diff --git a/tests/ui/offset-of/offset-of-dst-field.stderr b/tests/ui/offset-of/offset-of-dst-field.stderr
diff --git a/tests/ui/offset-of/offset-of-unstable.stderr b/tests/ui/offset-of/offset-of-unstable.stderr
