Rollup merge of #110694 - est31:builtin, r=petrochenkov

Implement builtin # syntax and use it for offset_of!(...)

Add `builtin #` syntax to the parser, as well as a generic infrastructure to support both item and expression position builtin syntaxes. The PR also uses this infrastructure for the implementation of the `offset_of!` macro, added by #106934.

cc `@petrochenkov` `@DrMeepster`

cc #110680 `builtin #` tracking issue
cc #106655 `offset_of!` tracking issue

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,

compiler/rustc_builtin_macros/src/offset_of.rs

@@ -1,99 +0,0 @@
-use rustc_ast as ast;
-use rustc_ast::ptr::P;
-use rustc_ast::token;
-use rustc_ast::tokenstream::TokenStream;
-use rustc_errors::PResult;
-use rustc_expand::base::{self, *};
-use rustc_macros::Diagnostic;
-use rustc_parse::parser::Parser;
-use rustc_span::{symbol::Ident, Span};
-
-#[derive(Diagnostic)]
-#[diag(builtin_macros_offset_of_expected_field)]
-struct ExpectedField {
-    #[primary_span]
-    span: Span,
-}
-
-#[derive(Diagnostic)]
-#[diag(builtin_macros_offset_of_expected_two_args)]
-struct ExpectedTwoArgs {
-    #[primary_span]
-    span: Span,
-}
-
-fn parse_field<'a>(cx: &ExtCtxt<'a>, p: &mut Parser<'a>) -> PResult<'a, Ident> {
-    let token = p.token.uninterpolate();
-    let field = match token.kind {
-        token::Ident(name, _) => Ident::new(name, token.span),
-        token::Literal(token::Lit { kind: token::Integer, symbol, suffix: None }) => {
-            Ident::new(symbol, token.span)
-        }
-        _ => return Err(cx.create_err(ExpectedField { span: p.token.span })),
-    };
-
-    p.bump();
-
-    Ok(field)
-}
-
-fn parse_args<'a>(
-    cx: &mut ExtCtxt<'a>,
-    sp: Span,
-    tts: TokenStream,
-) -> PResult<'a, (P<ast::Ty>, P<[Ident]>)> {
-    let mut p = cx.new_parser_from_tts(tts);
-
-    let container = p.parse_ty()?;
-
-    p.expect(&token::Comma)?;
-
-    if p.eat(&token::Eof) {
-        return Err(cx.create_err(ExpectedTwoArgs { span: sp }));
-    }
-
-    let mut fields = Vec::new();
-
-    loop {
-        let field = parse_field(cx, &mut p)?;
-        fields.push(field);
-
-        if p.eat(&token::Dot) {
-            continue;
-        }
-
-        p.eat(&token::Comma);
-
-        if !p.eat(&token::Eof) {
-            return Err(cx.create_err(ExpectedTwoArgs { span: sp }));
-        }
-
-        break;
-    }
-
-    Ok((container, fields.into()))
-}
-
-pub fn expand_offset_of<'cx>(
-    cx: &'cx mut ExtCtxt<'_>,
-    sp: Span,
-    tts: TokenStream,
-) -> Box<dyn base::MacResult + 'cx> {
-    match parse_args(cx, sp, tts) {
-        Ok((container, fields)) => {
-            let expr = P(ast::Expr {
-                id: ast::DUMMY_NODE_ID,
-                kind: ast::ExprKind::OffsetOf(container, fields),
-                span: sp,
-                attrs: ast::AttrVec::new(),
-                tokens: None,
-            });
-
-            MacEager::expr(expr)
-        }
-        Err(mut err) => {
-            err.emit();
-            DummyResult::any(sp)
-        }
-    }
-}