From d30b04674ea000c705749d0371e5086afdccec7a Mon Sep 17 00:00:00 2001
From: Daniel Kirchner <daniel@ekpyron.org>
Date: Tue, 14 Jun 2022 15:31:32 +0200
Subject: [PATCH] Add resolveUnaryTuples helper.

---
 libsolidity/analysis/ControlFlowBuilder.cpp |  7 ++-----
 libsolidity/ast/ASTUtils.cpp                | 10 ++++++++++
 libsolidity/ast/ASTUtils.h                  |  4 ++++
 3 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/libsolidity/analysis/ControlFlowBuilder.cpp b/libsolidity/analysis/ControlFlowBuilder.cpp
index 7c568b18e..06787a512 100644
--- a/libsolidity/analysis/ControlFlowBuilder.cpp
+++ b/libsolidity/analysis/ControlFlowBuilder.cpp
@@ -17,6 +17,7 @@
 // SPDX-License-Identifier: GPL-3.0
 
 #include <libsolidity/analysis/ControlFlowBuilder.h>
+#include <libsolidity/ast/ASTUtils.h>
 #include <libyul/AST.h>
 #include <libyul/backends/evm/EVMDialect.h>
 
@@ -617,11 +618,7 @@ bool ControlFlowBuilder::visit(VariableDeclarationStatement const& _variableDecl
 						solAssert(tupleExpression->components().size() > i, "");
 						expression = tupleExpression->components()[i].get();
 					}
-				while (auto tupleExpression = dynamic_cast<TupleExpression const*>(expression))
-					if (tupleExpression->components().size() == 1)
-						expression = tupleExpression->components().front().get();
-					else
-						break;
+				expression = resolveUnaryTuples(expression);
 				m_currentNode->variableOccurrences.emplace_back(
 					*var,
 					VariableOccurrence::Kind::Assignment,
diff --git a/libsolidity/ast/ASTUtils.cpp b/libsolidity/ast/ASTUtils.cpp
index 2b7ea7427..b4e75bace 100644
--- a/libsolidity/ast/ASTUtils.cpp
+++ b/libsolidity/ast/ASTUtils.cpp
@@ -85,4 +85,14 @@ VariableDeclaration const* rootConstVariableDeclaration(VariableDeclaration cons
 	return rootDecl;
 }
 
+Expression const* resolveUnaryTuples(Expression const* _expr)
+{
+	while (auto const* tupleExpression = dynamic_cast<TupleExpression const*>(_expr))
+		if (tupleExpression->components().size() == 1)
+			_expr = tupleExpression->components().front().get();
+		else
+			break;
+	return _expr;
+}
+
 }
diff --git a/libsolidity/ast/ASTUtils.h b/libsolidity/ast/ASTUtils.h
index 2bfbb8fe9..7ec79ef1b 100644
--- a/libsolidity/ast/ASTUtils.h
+++ b/libsolidity/ast/ASTUtils.h
@@ -38,4 +38,8 @@ bool isConstantVariableRecursive(VariableDeclaration const& _varDecl);
 /// Returns the innermost AST node that covers the given location or nullptr if not found.
 ASTNode const* locateInnermostASTNode(int _offsetInFile, SourceUnit const& _sourceUnit);
 
+/// @returns @a _expr itself, in case it is not an unary tuple expression. Otherwise it descends recursively
+/// into unary tuples and returns the contained expression.
+Expression const* resolveUnaryTuples(Expression const* _expr);
+
 }