syntax: Introduce default/with_unstable constructors for ExpnInfo

src/librustc/hir/lowering.rs

@@ -62,14 +62,14 @@ use syntax::errors;
 use syntax::ext::hygiene::{Mark, SyntaxContext};
 use syntax::print::pprust;
 use syntax::ptr::P;
-use syntax::source_map::{self, respan, CompilerDesugaringKind, Spanned};
+use syntax::source_map::{self, respan, ExpnInfo, CompilerDesugaringKind, Spanned};
 use syntax::source_map::CompilerDesugaringKind::IfTemporary;
 use syntax::std_inject;
 use syntax::symbol::{kw, sym, Symbol};
 use syntax::tokenstream::{TokenStream, TokenTree};
 use syntax::parse::token::{self, Token};
 use syntax::visit::{self, Visitor};
-use syntax_pos::{DUMMY_SP, edition, Span};
+use syntax_pos::{DUMMY_SP, Span};
 
 const HIR_ID_COUNTER_LOCKED: u32 = 0xFFFFFFFF;
 
@@ -853,14 +853,10 @@ impl<'a> LoweringContext<'a> {
         allow_internal_unstable: Option<Lrc<[Symbol]>>,
     ) -> Span {
         let mark = Mark::fresh(Mark::root());
-        mark.set_expn_info(source_map::ExpnInfo {
-            call_site: span,
+        mark.set_expn_info(ExpnInfo {
             def_site: Some(span),
-            format: source_map::CompilerDesugaring(reason),
             allow_internal_unstable,
-            allow_internal_unsafe: false,
-            local_inner_macros: false,
-            edition: edition::Edition::from_session(),
+            ..ExpnInfo::default(source_map::CompilerDesugaring(reason), span, self.sess.edition())
         });
         span.with_ctxt(SyntaxContext::empty().apply_mark(mark))
     }

src/librustc_allocator/expand.rs

@@ -19,7 +19,7 @@ use syntax::{
     mut_visit::{self, MutVisitor},
     parse::ParseSess,
     ptr::P,
-    symbol::{kw, sym, Symbol}
+    symbol::{kw, sym}
 };
 use syntax_pos::Span;
 
@@ -58,11 +58,10 @@ impl MutVisitor for ExpandAllocatorDirectives<'_> {
     fn flat_map_item(&mut self, item: P<Item>) -> SmallVec<[P<Item>; 1]> {
         debug!("in submodule {}", self.in_submod);
 
-        let name = if attr::contains_name(&item.attrs, sym::global_allocator) {
-            "global_allocator"
-        } else {
+        if !attr::contains_name(&item.attrs, sym::global_allocator) {
             return mut_visit::noop_flat_map_item(item, self);
-        };
+        }
+
         match item.node {
             ItemKind::Static(..) => {}
             _ => {
@@ -87,15 +86,9 @@ impl MutVisitor for ExpandAllocatorDirectives<'_> {
 
         // Create a fresh Mark for the new macro expansion we are about to do
         let mark = Mark::fresh(Mark::root());
-        mark.set_expn_info(ExpnInfo {
-            call_site: item.span, // use the call site of the static
-            def_site: None,
-            format: MacroAttribute(Symbol::intern(name)),
-            allow_internal_unstable: Some([sym::rustc_attrs][..].into()),
-            allow_internal_unsafe: false,
-            local_inner_macros: false,
-            edition: self.sess.edition,
-        });
+        mark.set_expn_info(ExpnInfo::with_unstable(
+            MacroAttribute(sym::global_allocator), item.span, self.sess.edition, &[sym::rustc_attrs]
+        ));
 
         // Tie the span to the macro expansion info we just created
         let span = item.span.with_ctxt(SyntaxContext::empty().apply_mark(mark));

src/libsyntax/ext/derive.rs

@@ -60,15 +60,10 @@ pub fn add_derived_markers<T>(cx: &mut ExtCtxt<'_>, span: Span, traits: &[ast::P
     }
     pretty_name.push(')');
 
-    cx.current_expansion.mark.set_expn_info(ExpnInfo {
-        call_site: span,
-        def_site: None,
-        format: ExpnFormat::MacroAttribute(Symbol::intern(&pretty_name)),
-        allow_internal_unstable: Some([sym::rustc_attrs, sym::structural_match][..].into()),
-        allow_internal_unsafe: false,
-        local_inner_macros: false,
-        edition: cx.parse_sess.edition,
-    });
+    cx.current_expansion.mark.set_expn_info(ExpnInfo::with_unstable(
+        ExpnFormat::MacroAttribute(Symbol::intern(&pretty_name)), span, cx.parse_sess.edition,
+        &[sym::rustc_attrs, sym::structural_match],
+    ));
 
     let span = span.with_ctxt(cx.backtrace());
     item.visit_attrs(|attrs| {

src/libsyntax/std_inject.rs

@@ -16,15 +16,9 @@ use syntax_pos::{DUMMY_SP, Span};
 /// The expanded code uses the unstable `#[prelude_import]` attribute.
 fn ignored_span(sp: Span, edition: Edition) -> Span {
     let mark = Mark::fresh(Mark::root());
-    mark.set_expn_info(ExpnInfo {
-        call_site: DUMMY_SP,
-        def_site: None,
-        format: MacroAttribute(Symbol::intern("std_inject")),
-        allow_internal_unstable: Some([sym::prelude_import][..].into()),
-        allow_internal_unsafe: false,
-        local_inner_macros: false,
-        edition,
-    });
+    mark.set_expn_info(ExpnInfo::with_unstable(
+        MacroAttribute(Symbol::intern("std_inject")), sp, edition, &[sym::prelude_import]
+    ));
     sp.with_ctxt(SyntaxContext::empty().apply_mark(mark))
 }
 

src/libsyntax/test.rs

@@ -280,15 +280,10 @@ fn generate_test_harness(sess: &ParseSess,
         test_runner
     };
 
-    mark.set_expn_info(ExpnInfo {
-        call_site: DUMMY_SP,
-        def_site: None,
-        format: MacroAttribute(sym::test_case),
-        allow_internal_unstable: Some([sym::main, sym::test, sym::rustc_attrs][..].into()),
-        allow_internal_unsafe: false,
-        local_inner_macros: false,
-        edition: sess.edition,
-    });
+    mark.set_expn_info(ExpnInfo::with_unstable(
+        MacroAttribute(sym::test_case), DUMMY_SP, sess.edition,
+        &[sym::main, sym::test, sym::rustc_attrs],
+    ));
 
     TestHarnessGenerator {
         cx,

src/libsyntax_ext/proc_macro_decls.rs

@@ -347,17 +347,10 @@ fn mk_decls(
     custom_macros: &[ProcMacroDef],
 ) -> P<ast::Item> {
     let mark = Mark::fresh(Mark::root());
-    mark.set_expn_info(ExpnInfo {
-        call_site: DUMMY_SP,
-        def_site: None,
-        format: MacroAttribute(sym::proc_macro),
-        allow_internal_unstable: Some([
-            sym::rustc_attrs, Symbol::intern("proc_macro_internals")
-        ][..].into()),
-        allow_internal_unsafe: false,
-        local_inner_macros: false,
-        edition: cx.parse_sess.edition,
-    });
+    mark.set_expn_info(ExpnInfo::with_unstable(
+        MacroAttribute(sym::proc_macro), DUMMY_SP, cx.parse_sess.edition,
+        &[sym::rustc_attrs, Symbol::intern("proc_macro_internals")],
+    ));
     let span = DUMMY_SP.apply_mark(mark);
 
     let hidden = cx.meta_list_item_word(span, sym::hidden);

src/libsyntax_ext/test.rs

@@ -8,7 +8,7 @@ use syntax::attr;
 use syntax::ast;
 use syntax::print::pprust;
 use syntax::symbol::{Symbol, sym};
-use syntax_pos::{DUMMY_SP, Span};
+use syntax_pos::Span;
 use syntax::source_map::{ExpnInfo, MacroAttribute};
 use std::iter;
 
@@ -62,15 +62,10 @@ pub fn expand_test_or_bench(
 
     let (sp, attr_sp) = {
         let mark = Mark::fresh(Mark::root());
-        mark.set_expn_info(ExpnInfo {
-            call_site: DUMMY_SP,
-            def_site: None,
-            format: MacroAttribute(sym::test),
-            allow_internal_unstable: Some([sym::rustc_attrs, sym::test][..].into()),
-            allow_internal_unsafe: false,
-            local_inner_macros: false,
-            edition: cx.parse_sess.edition,
-        });
+        mark.set_expn_info(ExpnInfo::with_unstable(
+            MacroAttribute(sym::test), attr_sp, cx.parse_sess.edition,
+            &[sym::rustc_attrs, sym::test],
+        ));
         (item.span.with_ctxt(SyntaxContext::empty().apply_mark(mark)),
          attr_sp.with_ctxt(SyntaxContext::empty().apply_mark(mark)))
     };

src/libsyntax_ext/test_case.rs

@@ -15,7 +15,7 @@ use syntax::ext::hygiene::{Mark, SyntaxContext};
 use syntax::ast;
 use syntax::source_map::respan;
 use syntax::symbol::sym;
-use syntax_pos::{DUMMY_SP, Span};
+use syntax_pos::Span;
 use syntax::source_map::{ExpnInfo, MacroAttribute};
 use syntax::feature_gate;
 
@@ -37,15 +37,10 @@ pub fn expand(
 
     let sp = {
         let mark = Mark::fresh(Mark::root());
-        mark.set_expn_info(ExpnInfo {
-            call_site: DUMMY_SP,
-            def_site: None,
-            format: MacroAttribute(sym::test_case),
-            allow_internal_unstable: Some([sym::test, sym::rustc_attrs][..].into()),
-            allow_internal_unsafe: false,
-            local_inner_macros: false,
-            edition: ecx.parse_sess.edition,
-        });
+        mark.set_expn_info(ExpnInfo::with_unstable(
+            MacroAttribute(sym::test_case), attr_sp, ecx.parse_sess.edition,
+            &[sym::test, sym::rustc_attrs],
+        ));
         attr_sp.with_ctxt(SyntaxContext::empty().apply_mark(mark))
     };
 

src/libsyntax_pos/hygiene.rs

@@ -682,6 +682,29 @@ pub struct ExpnInfo {
     pub edition: Edition,
 }
 
+impl ExpnInfo {
+    /// Constructs an expansion info with default properties.
+    pub fn default(format: ExpnFormat, call_site: Span, edition: Edition) -> ExpnInfo {
+        ExpnInfo {
+            call_site,
+            def_site: None,
+            format,
+            allow_internal_unstable: None,
+            allow_internal_unsafe: false,
+            local_inner_macros: false,
+            edition,
+        }
+    }
+
+    pub fn with_unstable(format: ExpnFormat, call_site: Span, edition: Edition,
+                         allow_internal_unstable: &[Symbol]) -> ExpnInfo {
+        ExpnInfo {
+            allow_internal_unstable: Some(allow_internal_unstable.into()),
+            ..ExpnInfo::default(format, call_site, edition)
+        }
+    }
+}
+
 /// The source of expansion.
 #[derive(Clone, Hash, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)]
 pub enum ExpnFormat {