Merge pull request #2199 from roadriverrail/no_unary_plus

Deprecate use of unary '+'

4 files changed, 40 insertions, 1 deletions

diff --git a/Changelog.md b/Changelog.md
index cd54aadb..c95cab5a 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -10,6 +10,7 @@ Features:
  * Inline Assembly: Storage variable access using ``_slot`` and ``_offset`` suffixes.
  * Inline Assembly: Disallow blocks with unbalanced stack.
  * Static analyzer: Warn about statements without effects.
+ * Syntax checker: issue deprecation warning for unary '+'
 
 Bugfixes:
  * Assembly output: Implement missing AssemblyItem types.
diff --git a/libsolidity/analysis/SyntaxChecker.cpp b/libsolidity/analysis/SyntaxChecker.cpp
index 89014133..94e82a87 100644
--- a/libsolidity/analysis/SyntaxChecker.cpp
+++ b/libsolidity/analysis/SyntaxChecker.cpp
@@ -32,6 +32,16 @@ bool SyntaxChecker::checkSyntax(ASTNode const& _astRoot)
 	return Error::containsOnlyWarnings(m_errors);
 }
 
+void SyntaxChecker::warning(SourceLocation const& _location, string const& _description)
+{
+	auto err = make_shared<Error>(Error::Type::Warning);
+	*err <<
+		errinfo_sourceLocation(_location) <<
+		errinfo_comment(_description);
+
+	m_errors.push_back(err);
+}
+
 void SyntaxChecker::syntaxError(SourceLocation const& _location, std::string const& _description)
 {
 	auto err = make_shared<Error>(Error::Type::SyntaxError);
@@ -148,6 +158,13 @@ bool SyntaxChecker::visit(Break const& _breakStatement)
 	return true;
 }
 
+bool SyntaxChecker::visit(UnaryOperation const& _operation)
+{
+	if (_operation.getOperator() == Token::Add)
+		warning(_operation.location(), "Use of unary + is deprecated.");
+	return true;
+}
+
 bool SyntaxChecker::visit(PlaceholderStatement const&)
 {
 	m_placeholderFound = true;
diff --git a/libsolidity/analysis/SyntaxChecker.h b/libsolidity/analysis/SyntaxChecker.h
index 308e128b..8d7dcdd3 100644
--- a/libsolidity/analysis/SyntaxChecker.h
+++ b/libsolidity/analysis/SyntaxChecker.h
@@ -32,6 +32,7 @@ namespace solidity
  * The module that performs syntax analysis on the AST:
  *  - whether continue/break is in a for/while loop.
  *  - whether a modifier contains at least one '_'
+ *  - issues deprecation warnings for unary '+'
  */
 class SyntaxChecker: private ASTConstVisitor
 {
@@ -43,6 +44,7 @@ public:
 
 private:
 	/// Adds a new error to the list of errors.
+	void warning(SourceLocation const& _location, std::string const& _description);
 	void syntaxError(SourceLocation const& _location, std::string const& _description);
 
 	virtual bool visit(SourceUnit const& _sourceUnit) override;
@@ -60,6 +62,8 @@ private:
 	virtual bool visit(Continue const& _continueStatement) override;
 	virtual bool visit(Break const& _breakStatement) override;
 
+	virtual bool visit(UnaryOperation const& _operation) override;
+
 	virtual bool visit(PlaceholderStatement const& _placeholderStatement) override;
 
 	ErrorList& m_errors;
diff --git a/test/libsolidity/SolidityNameAndTypeResolution.cpp b/test/libsolidity/SolidityNameAndTypeResolution.cpp
index f88f600a..90d0e728 100644
--- a/test/libsolidity/SolidityNameAndTypeResolution.cpp
+++ b/test/libsolidity/SolidityNameAndTypeResolution.cpp
@@ -3938,12 +3938,29 @@ BOOST_AUTO_TEST_CASE(rational_unary_operation)
 	char const* text = R"(
 		contract test {
 			function f() {
+				ufixed8x16 a = 3.25;
+				fixed8x16 b = -3.25;
+			}
+		}
+	)";
+	CHECK_SUCCESS_NO_WARNINGS(text);
+	text = R"(
+		contract test {
+			function f() {
 				ufixed8x16 a = +3.25;
 				fixed8x16 b = -3.25;
 			}
 		}
 	)";
-	CHECK_SUCCESS(text);
+	CHECK_WARNING(text,"Use of unary + is deprecated");
+	text = R"(
+		contract test {
+			function f(uint x) {
+				uint y = +x;
+			}
+		}
+	)";
+	CHECK_WARNING(text,"Use of unary + is deprecated");
 }
 
 BOOST_AUTO_TEST_CASE(leading_zero_rationals_convert)