From 37e01a19c0c24f32ecdb978aa7c17db71fd5c769 Mon Sep 17 00:00:00 2001
From: chriseth <chris@ethereum.org>
Date: Sun, 8 Mar 2020 17:27:43 +0100
Subject: [PATCH] Fix scoping following try/catch.

---
 Changelog.md                                     |  1 +
 libsolidity/analysis/ReferencesResolver.cpp      | 16 ++++++++++++++++
 libsolidity/analysis/ReferencesResolver.h        |  2 ++
 .../libsolidity/syntaxTests/tryCatch/scoping.sol | 10 ++++++++++
 4 files changed, 29 insertions(+)
 create mode 100644 test/libsolidity/syntaxTests/tryCatch/scoping.sol

diff --git a/Changelog.md b/Changelog.md
index a86b3ac59..92e31b9dc 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -12,6 +12,7 @@ Compiler Features:
 Bugfixes:
  * Inheritance: Fix incorrect error on calling unimplemented base functions.
  * isoltest: Added new keyword `wei` to express function value in semantic tests
+ * Reference Resolver: Fix scoping issue following try/catch statements.
  * Standard-JSON-Interface: Fix a bug related to empty filenames and imports.
  * SMTChecker: Fix internal errors when analysing tuples.
  * Yul AST Import: correctly import blocks as statements, switch statements and string literals.
diff --git a/libsolidity/analysis/ReferencesResolver.cpp b/libsolidity/analysis/ReferencesResolver.cpp
index 4fe2d01c9..6867f049c 100644
--- a/libsolidity/analysis/ReferencesResolver.cpp
+++ b/libsolidity/analysis/ReferencesResolver.cpp
@@ -67,6 +67,22 @@ void ReferencesResolver::endVisit(Block const& _block)
 	m_resolver.setScope(_block.scope());
 }
 
+bool ReferencesResolver::visit(TryCatchClause const& _tryCatchClause)
+{
+	if (!m_resolveInsideCode)
+		return false;
+	m_resolver.setScope(&_tryCatchClause);
+	return true;
+}
+
+void ReferencesResolver::endVisit(TryCatchClause const& _tryCatchClause)
+{
+	if (!m_resolveInsideCode)
+		return;
+
+	m_resolver.setScope(_tryCatchClause.scope());
+}
+
 bool ReferencesResolver::visit(ForStatement const& _for)
 {
 	if (!m_resolveInsideCode)
diff --git a/libsolidity/analysis/ReferencesResolver.h b/libsolidity/analysis/ReferencesResolver.h
index c560be31e..488562f21 100644
--- a/libsolidity/analysis/ReferencesResolver.h
+++ b/libsolidity/analysis/ReferencesResolver.h
@@ -70,6 +70,8 @@ private:
 
 	bool visit(Block const& _block) override;
 	void endVisit(Block const& _block) override;
+	bool visit(TryCatchClause const& _tryCatchClause) override;
+	void endVisit(TryCatchClause const& _tryCatchClause) override;
 	bool visit(ForStatement const& _for) override;
 	void endVisit(ForStatement const& _for) override;
 	void endVisit(VariableDeclarationStatement const& _varDeclStatement) override;
diff --git a/test/libsolidity/syntaxTests/tryCatch/scoping.sol b/test/libsolidity/syntaxTests/tryCatch/scoping.sol
new file mode 100644
index 000000000..3c902c336
--- /dev/null
+++ b/test/libsolidity/syntaxTests/tryCatch/scoping.sol
@@ -0,0 +1,10 @@
+contract Test {
+  // This checks a scoping error,
+  // the variable "a" was not visible
+  // at the assignment.
+  function test(address _ext) external {
+    try Test(_ext).test(_ext) {} catch {}
+    uint a = 1;
+    a = 3;
+  }
+}