Warn about functions named "constructor".

Changelog.md

@@ -1,8 +1,9 @@
 ### 0.4.23 (unreleased)
 
 Features:
- * SMTChecker: Integration with CVC4 SMT solver
  * Build system: Support Ubuntu Bionic.
+ * SMTChecker: Integration with CVC4 SMT solver
+ * Syntax Checker: Warn about functions named "constructor".
 
 Bugfixes:
  * Type Checker: Do not complain about new-style constructor and fallback function to have the same name.

libsolidity/analysis/SyntaxChecker.cpp

@@ -237,8 +237,13 @@ bool SyntaxChecker::visit(FunctionDefinition const& _function)
 		if (v050)
 			m_errorReporter.syntaxError(_function.location(), "Functions without implementation cannot have modifiers.");
 		else
-			m_errorReporter.warning( _function.location(), "Modifiers of functions without implementation are ignored." );
+			m_errorReporter.warning(_function.location(), "Modifiers of functions without implementation are ignored." );
 	}
+	if (_function.name() == "constructor")
+		m_errorReporter.warning(_function.location(),
+			"This function is named \"constructor\" but is not the constructor of the contract. "
+			"If you intend this to be a constructor, use \"constructor(...) { ... }\" without the \"function\" keyword to define it."
+		);
 	return true;
 }
 

test/libsolidity/syntaxTests/constructor/function_named_constructor.sol

@@ -0,0 +1,5 @@
+contract C {
+    function constructor() public;
+}
+// ----
+// Warning: (17-47): This function is named "constructor" but is not the constructor of the contract. If you intend this to be a constructor, use "constructor(...) { ... }" without the "function" keyword to define it.