Auto merge of #51762 - petrochenkov:oh-hi-mark, r=oli-obk

hygiene: Implement transparent marks and use them for call-site hygiene in proc-macros

Fixes https://github.com/rust-lang/rust/issues/50050

src/libsyntax/parse/parser.rs

@@ -43,7 +43,7 @@ use ast::{BinOpKind, UnOp};
 use ast::{RangeEnd, RangeSyntax};
 use {ast, attr};
 use codemap::{self, CodeMap, Spanned, respan};
-use syntax_pos::{self, Span, MultiSpan, BytePos, FileName, DUMMY_SP, edition::Edition};
+use syntax_pos::{self, Span, MultiSpan, BytePos, FileName, edition::Edition};
 use errors::{self, Applicability, DiagnosticBuilder};
 use parse::{self, SeqSep, classify, token};
 use parse::lexer::TokenAndSpan;
@@ -567,7 +567,7 @@ impl<'a> Parser<'a> {
 
         if let Some(directory) = directory {
             parser.directory = directory;
-        } else if !parser.span.source_equal(&DUMMY_SP) {
+        } else if !parser.span.is_dummy() {
             if let FileName::Real(mut path) = sess.codemap().span_to_unmapped_path(parser.span) {
                 path.pop();
                 parser.directory.path = Cow::from(path);
@@ -584,7 +584,7 @@ impl<'a> Parser<'a> {
         } else {
             self.token_cursor.next()
         };
-        if next.sp == syntax_pos::DUMMY_SP {
+        if next.sp.is_dummy() {
             // Tweak the location for better diagnostics, but keep syntactic context intact.
             next.sp = self.prev_span.with_ctxt(next.sp.ctxt());
         }
@@ -6138,7 +6138,7 @@ impl<'a> Parser<'a> {
             return Err(err);
         }
 
-        let hi = if self.span == syntax_pos::DUMMY_SP {
+        let hi = if self.span.is_dummy() {
             inner_lo
         } else {
             self.prev_span
@@ -6369,7 +6369,7 @@ impl<'a> Parser<'a> {
                 }
                 let mut err = self.diagnostic().struct_span_err(id_sp,
                     "cannot declare a new module at this location");
-                if id_sp != syntax_pos::DUMMY_SP {
+                if !id_sp.is_dummy() {
                     let src_path = self.sess.codemap().span_to_filename(id_sp);
                     if let FileName::Real(src_path) = src_path {
                         if let Some(stem) = src_path.file_stem() {