[clang][Interp] Lambda This captures can be non-pointers

If they are captured by value.

Author: tbaederr

clang/lib/AST/Interp/ByteCodeEmitter.cpp

@@ -108,8 +108,12 @@ Function *ByteCodeEmitter::compileFunc(const FunctionDecl *FuncDecl) {
         this->LambdaCaptures[Cap.first] = {
             Offset, Cap.second->getType()->isReferenceType()};
       }
-      if (LTC)
-        this->LambdaThisCapture = R->getField(LTC)->Offset;
+      if (LTC) {
+        QualType CaptureType = R->getField(LTC)->Decl->getType();
+        this->LambdaThisCapture = {R->getField(LTC)->Offset,
+                                   CaptureType->isReferenceType() ||
+                                       CaptureType->isPointerType()};
+      }
     }
   }
 

clang/lib/AST/Interp/ByteCodeEmitter.h

@@ -62,7 +62,7 @@ class ByteCodeEmitter {
   /// Lambda captures.
   llvm::DenseMap<const ValueDecl *, ParamOffset> LambdaCaptures;
   /// Offset of the This parameter in a lambda record.
-  unsigned LambdaThisCapture = 0;
+  ParamOffset LambdaThisCapture{0, false};
   /// Local descriptors.
   llvm::SmallVector<SmallVector<Local, 8>, 2> Descriptors;
 

clang/lib/AST/Interp/ByteCodeExprGen.cpp

@@ -2934,8 +2934,11 @@ bool ByteCodeExprGen<Emitter>::VisitCXXThisExpr(const CXXThisExpr *E) {
   if (DiscardResult)
     return true;
 
-  if (this->LambdaThisCapture > 0)
-    return this->emitGetThisFieldPtr(this->LambdaThisCapture, E);
+  if (this->LambdaThisCapture.Offset > 0) {
+    if (this->LambdaThisCapture.IsPtr)
+      return this->emitGetThisFieldPtr(this->LambdaThisCapture.Offset, E);
+    return this->emitGetPtrThisField(this->LambdaThisCapture.Offset, E);
+  }
 
   return this->emitThis(E);
 }

clang/lib/AST/Interp/EvalEmitter.h

@@ -73,7 +73,7 @@ class EvalEmitter : public SourceMapper {
   /// Lambda captures.
   llvm::DenseMap<const ValueDecl *, ParamOffset> LambdaCaptures;
   /// Offset of the This parameter in a lambda record.
-  unsigned LambdaThisCapture = 0;
+  ParamOffset LambdaThisCapture{0, false};
   /// Local descriptors.
   llvm::SmallVector<SmallVector<Local, 8>, 2> Descriptors;
 

clang/test/AST/Interp/lambda.cpp

@@ -235,3 +235,16 @@ namespace LambdaToAPValue {
     static_assert(g() == f(), "");
   }
 }
+
+namespace ns2_capture_this_byval {
+  struct S {
+    int s;
+    constexpr S(int s) : s{s} { }
+    constexpr auto f(S o) {
+      return [*this,o] (auto a) { return s + o.s + a.s; };
+    }
+  };
+
+  constexpr auto L = S{5}.f(S{10});
+  static_assert(L(S{100}) == 115, "");
+} // end test_captures_1::ns2_capture_this_byval