[clang][bytecode] Move generic lambda handling to Compiler (#159733)

So the static invoker's Function still points to the static invoker
instead of the call operator of the lambda record. This is important for
a later commit.

Author: tbaederr

clang/lib/AST/ByteCode/Compiler.cpp

@@ -6077,7 +6077,24 @@ bool Compiler<Emitter>::emitLambdaStaticInvokerBody(const CXXMethodDecl *MD) {
   assert(cast<CompoundStmt>(MD->getBody())->body_empty());
 
   const CXXRecordDecl *ClosureClass = MD->getParent();
-  const CXXMethodDecl *LambdaCallOp = ClosureClass->getLambdaCallOperator();
+  const FunctionDecl *LambdaCallOp;
+  assert(ClosureClass->captures().empty());
+  if (ClosureClass->isGenericLambda()) {
+    LambdaCallOp = ClosureClass->getLambdaCallOperator();
+    assert(MD->isFunctionTemplateSpecialization() &&
+           "A generic lambda's static-invoker function must be a "
+           "template specialization");
+    const TemplateArgumentList *TAL = MD->getTemplateSpecializationArgs();
+    FunctionTemplateDecl *CallOpTemplate =
+        LambdaCallOp->getDescribedFunctionTemplate();
+    void *InsertPos = nullptr;
+    const FunctionDecl *CorrespondingCallOpSpecialization =
+        CallOpTemplate->findSpecialization(TAL->asArray(), InsertPos);
+    assert(CorrespondingCallOpSpecialization);
+    LambdaCallOp = CorrespondingCallOpSpecialization;
+  } else {
+    LambdaCallOp = ClosureClass->getLambdaCallOperator();
+  }
   assert(ClosureClass->captures().empty());
   const Function *Func = this->getFunction(LambdaCallOp);
   if (!Func)

clang/lib/AST/ByteCode/Context.cpp

@@ -465,23 +465,6 @@ const Function *Context::getOrCreateFunction(const FunctionDecl *FuncDecl) {
     // be a non-static member function, this (usually) requiring an
     // instance pointer. We suppress that later in this function.
     IsLambdaStaticInvoker = true;
-
-    const CXXRecordDecl *ClosureClass = MD->getParent();
-    assert(ClosureClass->captures().empty());
-    if (ClosureClass->isGenericLambda()) {
-      const CXXMethodDecl *LambdaCallOp = ClosureClass->getLambdaCallOperator();
-      assert(MD->isFunctionTemplateSpecialization() &&
-             "A generic lambda's static-invoker function must be a "
-             "template specialization");
-      const TemplateArgumentList *TAL = MD->getTemplateSpecializationArgs();
-      FunctionTemplateDecl *CallOpTemplate =
-          LambdaCallOp->getDescribedFunctionTemplate();
-      void *InsertPos = nullptr;
-      const FunctionDecl *CorrespondingCallOpSpecialization =
-          CallOpTemplate->findSpecialization(TAL->asArray(), InsertPos);
-      assert(CorrespondingCallOpSpecialization);
-      FuncDecl = CorrespondingCallOpSpecialization;
-    }
   }
   // Set up argument indices.
   unsigned ParamOffset = 0;