Analyze InlineAssembly for variable use

The unused variable checker in StaticAnalyzer did not conssider
InlineAssembly objects.  This commit introduces that missing feature.

4 files changed, 41 insertions, 2 deletions

diff --git a/Changelog.md b/Changelog.md
index be5c18c5..9673a057 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -1,5 +1,8 @@
 ### 0.4.12 (unreleased)
 
+Bugfixes:
+ * Unused variable warnings no longer issued for variables used inside inline assembly
+
 ### 0.4.11 (2017-05-03)
 
 Features:
diff --git a/libsolidity/analysis/StaticAnalyzer.cpp b/libsolidity/analysis/StaticAnalyzer.cpp
index 369376fa..d273b26e 100644
--- a/libsolidity/analysis/StaticAnalyzer.cpp
+++ b/libsolidity/analysis/StaticAnalyzer.cpp
@@ -21,14 +21,16 @@
  */
 
 #include <libsolidity/analysis/StaticAnalyzer.h>
-#include <memory>
 #include <libsolidity/ast/AST.h>
+#include <libsolidity/inlineasm/AsmAnalysis.h>
+#include <libsolidity/inlineasm/AsmAnalysisInfo.h>
+#include <libsolidity/inlineasm/AsmData.h>
+#include <memory>
 
 using namespace std;
 using namespace dev;
 using namespace dev::solidity;
 
-
 bool StaticAnalyzer::analyze(SourceUnit const& _sourceUnit)
 {
 	_sourceUnit.accept(*this);
@@ -128,3 +130,22 @@ void StaticAnalyzer::warning(SourceLocation const& _location, string const& _des
 
 	m_errors.push_back(err);
 }
+
+bool StaticAnalyzer::visit(InlineAssembly const& _inlineAssembly)
+{
+	if (!m_currentFunction)
+		return true;
+
+	for (auto const& ref: _inlineAssembly.annotation().externalReferences)
+	{
+		if (auto var = dynamic_cast<VariableDeclaration const*>(ref.second.declaration))
+		{
+			solAssert(!var->name().empty(), "");
+			if (var->isLocalVariable())
+				m_localVarUseCount[var] += 1;
+		}
+	}
+
+	return true;
+}
+
diff --git a/libsolidity/analysis/StaticAnalyzer.h b/libsolidity/analysis/StaticAnalyzer.h
index ab72e7d9..458bab2a 100644
--- a/libsolidity/analysis/StaticAnalyzer.h
+++ b/libsolidity/analysis/StaticAnalyzer.h
@@ -65,6 +65,7 @@ private:
 	virtual bool visit(Identifier const& _identifier) override;
 	virtual bool visit(Return const& _return) override;
 	virtual bool visit(MemberAccess const& _memberAccess) override;
+	virtual bool visit(InlineAssembly const& _inlineAssembly) override;
 
 	ErrorList& m_errors;
 
diff --git a/test/libsolidity/SolidityNameAndTypeResolution.cpp b/test/libsolidity/SolidityNameAndTypeResolution.cpp
index 3a9f7295..97c4303f 100644
--- a/test/libsolidity/SolidityNameAndTypeResolution.cpp
+++ b/test/libsolidity/SolidityNameAndTypeResolution.cpp
@@ -5718,6 +5718,20 @@ BOOST_AUTO_TEST_CASE(no_unused_dec_after_use)
 	CHECK_SUCCESS_NO_WARNINGS(text);
 }
 
+BOOST_AUTO_TEST_CASE(no_unused_inline_asm)
+{
+	char const* text = R"(
+		contract C {
+			function f() {
+				uint a;
+				assembly {
+					a := 1
+				}
+			}
+		}
+	)";
+	CHECK_SUCCESS_NO_WARNINGS(text);
+}