Suggests external for fallback and interface functions.

2 files changed, 15 insertions, 1 deletions

diff --git a/libsolidity/analysis/SyntaxChecker.cpp b/libsolidity/analysis/SyntaxChecker.cpp
index 234c177c..4d09e36d 100644
--- a/libsolidity/analysis/SyntaxChecker.cpp
+++ b/libsolidity/analysis/SyntaxChecker.cpp
@@ -197,12 +197,24 @@ bool SyntaxChecker::visit(PlaceholderStatement const&)
 	return true;
 }
 
+bool SyntaxChecker::visit(ContractDefinition const& _contract)
+{
+	m_isInterface = _contract.contractKind() == ContractDefinition::ContractKind::Interface;
+	return true;
+}
+
 bool SyntaxChecker::visit(FunctionDefinition const& _function)
 {
 	bool const v050 = m_sourceUnit->annotation().experimentalFeatures.count(ExperimentalFeature::V050);
 
 	if (_function.noVisibilitySpecified())
-		m_errorReporter.syntaxError(_function.location(), "No visibility specified.");
+	{
+		string suggestedVisibility = _function.isFallback() || m_isInterface ? "external" : "public";
+		m_errorReporter.syntaxError(
+			_function.location(),
+			"No visibility specified. Did you intend to add \"" + suggestedVisibility + "\"?"
+		);
+	}
 
 	if (_function.isOldStyleConstructor())
 	{
diff --git a/libsolidity/analysis/SyntaxChecker.h b/libsolidity/analysis/SyntaxChecker.h
index 5460e3be..28a0f66e 100644
--- a/libsolidity/analysis/SyntaxChecker.h
+++ b/libsolidity/analysis/SyntaxChecker.h
@@ -66,6 +66,7 @@ private:
 
 	virtual bool visit(PlaceholderStatement const& _placeholderStatement) override;
 
+	virtual bool visit(ContractDefinition const& _contract) override;
 	virtual bool visit(FunctionDefinition const& _function) override;
 	virtual bool visit(FunctionTypeName const& _node) override;
 
@@ -82,6 +83,7 @@ private:
 	bool m_versionPragmaFound = false;
 
 	int m_inLoopDepth = 0;
+	bool m_isInterface = false;
 
 	SourceUnit const* m_sourceUnit = nullptr;
 };