[Demangle][Rust] Parse dyn-trait

[tmiasko]

Summary

Depends on D103151

[dblaikie]

Looks good, thanks!

llvm/lib/Demangle/RustDemangle.cpp

548–560

This could be:

bool First = true;
while (!Error && !consumeIf('E'))
  if (First)
    print(" + ");
  First = false; // this could go inside the `if` above, or not - whichever seems more readable
  ...

Avoiding the increment on every iteration - I guess it'll probably optimize down to the same anyway, hopefully. So up to you if you reckon that might be more readable.

[tmiasko]

Rebase

llvm/include/llvm/Demangle/RustDemangle.h

 
 private:
   void demanglePath(InType InType);
   void demangleImplPath(InType InType);
   void demangleGenericArg();
   void demangleType();
   void demangleFnSig();
   void demangleDynBounds();
+  void demangleDynTrait();
   void demangleOptionalBinder();
   void demangleConst();
   void demangleConstInt();
   void demangleConstBool();
   void demangleConstChar();
 
   Identifier parseIdentifier();
   uint64_t parseOptionalBase62Number(char Tag);

llvm/lib/Demangle/RustDemangle.cpp

void Demangler::demangleFnSig() {
   }
 }
 
 // <dyn-bounds> = [<binder>] {<dyn-trait>} "E"
 void Demangler::demangleDynBounds() {
   SwapAndRestore<size_t> SaveBoundLifetimes(BoundLifetimes, BoundLifetimes);
   print("dyn ");
   demangleOptionalBinder();
-  // FIXME demangle {dyn-trait}
-  if (!consumeIf('E'))
-    Error = true;
+  for (size_t I = 0; !Error && !consumeIf('E'); ++I) {
+    if (I > 0)
+      print(" + ");
+    demangleDynTrait();
+  }
+}
+
+// <dyn-trait> = <path> {<dyn-trait-assoc-binding>}
+// <dyn-trait-assoc-binding> = "p" <undisambiguated-identifier> <type>
+void Demangler::demangleDynTrait() {
+  demanglePath(InType::Yes);
+  // FIXME demangle {<dyn-trait-assoc-binding>}
 }
 
 // Demangles optional binder and updates the number of bound lifetimes.
 //
 // <binder> = "G" <base-62-number>
 void Demangler::demangleOptionalBinder() {
   uint64_t Binder = parseOptionalBase62Number('G');
   if (Error || Binder == 0)
     return;

llvm/test/Demangle/rust.test

CHECK: trait::<dyn >
        _RIC5traitDEL_E
 
 CHECK: trait::<dyn for<'a> >
        _RIC5traitDG_EL_E
 
 CHECK: trait::<for<'a> fn(dyn for<'b> + 'a)>
        _RIC5traitFG_DG_EL0_EuE
 
+CHECK: trait::<dyn Display>
+       _RIC5traitDC7DisplayEL_E
+
+CHECK: trait::<dyn Display + Send + Sync>
+       _RIC5traitDC7DisplayC4SendC4SyncEL_E
+
+CHECK: trait::<dyn for<'a> Display>
+       _RIC5traitDG_C7DisplayEL_E
+
 ; Invalid trait object, missing lifetime.
 
 CHECK: _RIC5traitDEE
        _RIC5traitDEE
 
 ; Binders
 
 CHECK: binders::<for<'a> fn(&'a _)>