@@ -39,6 +39,7 @@ pub(super) fn mangle<'tcx>(
3939 consts : FxHashMap :: default ( ) ,
4040 binders : vec ! [ ] ,
4141 out : String :: from ( prefix) ,
42+ wrapper_level : GrammarFeatureLevel :: BASE_LINE ,
4243 } ;
4344
4445 // Append `::{shim:...#0}` to shims that can coexist with a non-shim instance.
@@ -79,11 +80,13 @@ pub(super) fn mangle_typeid_for_trait_ref<'tcx>(
7980 consts : FxHashMap :: default ( ) ,
8081 binders : vec ! [ ] ,
8182 out : String :: new ( ) ,
83+ wrapper_level : GrammarFeatureLevel :: BASE_LINE ,
8284 } ;
8385 cx. print_def_path ( trait_ref. def_id ( ) , & [ ] ) . unwrap ( ) ;
8486 std:: mem:: take ( & mut cx. out )
8587}
8688
89+ #[ derive( Clone ) ]
8790struct BinderLevel {
8891 /// The range of distances from the root of what's
8992/// being printed, to the lifetimes in a binder.
@@ -98,6 +101,15 @@ struct BinderLevel {
98101lifetime_depths : Range < u32 > ,
99102}
100103
104+ #[ derive( Clone , Copy , PartialEq , Eq , PartialOrd , Ord ) ]
105+ struct GrammarFeatureLevel ( usize ) ;
106+
107+ impl GrammarFeatureLevel {
108+ const BASE_LINE : GrammarFeatureLevel = GrammarFeatureLevel ( 0 ) ;
109+ const COMPLEX_CONST_GENERICS : GrammarFeatureLevel = GrammarFeatureLevel ( 1 ) ;
110+ }
111+
112+ #[ derive( Clone ) ]
101113struct SymbolMangler < ' tcx > {
102114 tcx : TyCtxt < ' tcx > ,
103115 binders : Vec < BinderLevel > ,
@@ -109,6 +121,8 @@ struct SymbolMangler<'tcx> {
109121paths : FxHashMap < ( DefId , & ' tcx [ GenericArg < ' tcx > ] ) , usize > ,
110122 types : FxHashMap < Ty < ' tcx > , usize > ,
111123 consts : FxHashMap < ty:: Const < ' tcx > , usize > ,
124+
125+ wrapper_level : GrammarFeatureLevel ,
112126}
113127
114128impl < ' tcx > SymbolMangler < ' tcx > {
@@ -192,6 +206,75 @@ impl<'tcx> SymbolMangler<'tcx> {
192206
193207 Ok ( ( ) )
194208 }
209+
210+ fn required_feature_level_for_const ( & self , ct : ty:: Const < ' tcx > ) -> GrammarFeatureLevel {
211+ let ct = ct. normalize ( self . tcx , ty:: ParamEnv :: reveal_all ( ) ) ;
212+ match ct. kind ( ) {
213+ ty:: ConstKind :: Value ( _) => { }
214+
215+ ty:: ConstKind :: Unevaluated ( _)
216+ | ty:: ConstKind :: Expr ( _)
217+ | ty:: ConstKind :: Param ( _)
218+ | ty:: ConstKind :: Infer ( _)
219+ | ty:: ConstKind :: Bound ( ..)
220+ | ty:: ConstKind :: Placeholder ( _)
221+ | ty:: ConstKind :: Error ( _) => {
222+ return GrammarFeatureLevel :: BASE_LINE ;
223+ }
224+ }
225+
226+ let ty = ct. ty ( ) ;
227+
228+ match ty. kind ( ) {
229+ ty:: Uint ( _) | ty:: Int ( _) | ty:: Bool | ty:: Char => GrammarFeatureLevel :: BASE_LINE ,
230+ _ => GrammarFeatureLevel :: COMPLEX_CONST_GENERICS ,
231+ }
232+ }
233+
234+ fn wrapped (
235+ & mut self ,
236+ level : GrammarFeatureLevel ,
237+ f : & mut dyn FnMut ( & mut Self ) -> Result < ( ) , PrintError > ,
238+ ) -> Result < ( ) , PrintError > {
239+ if self . wrapper_level >= level {
240+ return f ( self ) ;
241+ }
242+
243+ self . out . push ( 'C' ) ;
244+ let backup = self . clone ( ) ;
245+
246+ let mut digit_count = 2 ;
247+
248+ for _iteration in 0 ..10 {
249+ self . wrapper_level = level;
250+ let digit_range = self . out . len ( ) ..self . out . len ( ) + digit_count;
251+ for _ in 0 ..digit_count {
252+ self . out . push ( '#' ) ;
253+ }
254+
255+ self . out . push ( '_' ) ;
256+
257+ let start = self . out . len ( ) ;
258+
259+ f ( self ) ?;
260+
261+ let end = self . out . len ( ) ;
262+ let fragment_length = format ! ( "{}" , end - start) ;
263+
264+ // FIXME: Add check if any back references to interior were made. If
265+ // not, we can just shift everything without remangling.
266+ if fragment_length. len ( ) == digit_count {
267+ self . out . replace_range ( digit_range, & fragment_length) ;
268+ self . wrapper_level = backup. wrapper_level ;
269+ return Ok ( ( ) ) ;
270+ }
271+
272+ * self = backup. clone ( ) ;
273+ digit_count = fragment_length. len ( ) ;
274+ }
275+
276+ Err ( PrintError :: default ( ) )
277+ }
195278}
196279
197280impl < ' tcx > Printer < ' tcx > for SymbolMangler < ' tcx > {
@@ -813,8 +896,12 @@ impl<'tcx> Printer<'tcx> for SymbolMangler<'tcx> {
813896 ty. print ( self ) ?;
814897 }
815898 GenericArgKind :: Const ( c) => {
816- self . push ( "K" ) ;
817- c. print ( self ) ?;
899+ let required_feature_level = self . required_feature_level_for_const ( c) ;
900+
901+ self . wrapped ( required_feature_level, & mut |this| {
902+ this. push ( "K" ) ;
903+ c. print ( this)
904+ } ) ?;
818905 }
819906 }
820907 }
0 commit comments