switch in forwardanalyzer

lib/analyzer.h

@@ -147,6 +147,8 @@ struct Analyzer {
     virtual void forkScope(const Token* /*endBlock*/) {}
     /// If the value is conditional
     virtual bool isConditional() const = 0;
+    /// If the value is known
+    virtual bool isKnown() const = 0;
     /// The condition that will be assumed during analysis
     virtual void assume(const Token* tok, bool state, unsigned int flags = 0) = 0;
     /// Return analyzer for expression at token

lib/forwardanalyzer.cpp

@@ -652,6 +652,31 @@ struct ForwardTraversal {
             } else if (Token::simpleMatch(tok, "switch (")) {
                 if (updateRecursive(tok->next()->astOperand2()) == Progress::Break)
                     return Break();
+                if (!analyzer->isKnown())
+                    return Break();
+                Token *bodyStart = tok->linkAt(1)->next();
+                const Token *bodyEnd = bodyStart->link();
+                bool known = true;
+                for (Token *bodyTok = bodyStart->next(); bodyTok != bodyEnd; bodyTok = bodyTok->next()) {
+                    if (bodyTok->str() == "{")
+                        bodyTok = bodyTok->link();
+                    known |= Token::Match(bodyTok, "return|throw|break");
+                    if (!Token::Match(bodyTok, "case %any% :") && !Token::simpleMatch(bodyTok, "default :"))
+                        continue;
+                    while (Token::Match(bodyTok, "case %any% :") || Token::simpleMatch(bodyTok, "default :")) {
+                        bodyTok = bodyTok->tokAt(2);
+                        while (Token::Match(bodyTok, "[;:]"))
+                            bodyTok = bodyTok->next();
+                    }
+
+                    ForwardTraversal ft = *this;
+                    ft.analyzer->forkScope(bodyEnd);
+                    if (!known)
+                        ft.analyzer->lowerToPossible();
+                    ft.updateRange(bodyTok, bodyEnd, depth - 1);
+                    known = false;
+                    bodyTok = bodyTok->previous();
+                }
                 return Break();
             } else {
                 if (updateTok(tok, &next) == Progress::Break)

lib/valueflow.cpp

@@ -2319,6 +2319,10 @@ struct SingleValueFlowAnalyzer : ValueFlowAnalyzer {
         return false;
     }
 
+    virtual bool isKnown() const OVERRIDE {
+        return value.isKnown();
+    }
+
     virtual bool updateScope(const Token* endBlock, bool) const OVERRIDE {
         const Scope* scope = endBlock->scope();
         if (!scope)
@@ -5305,6 +5309,14 @@ struct MultiValueFlowAnalyzer : ValueFlowAnalyzer {
         return false;
     }
 
+    virtual bool isKnown() const OVERRIDE {
+        for (auto&& p:values) {
+            if (!p.second.isKnown())
+                return false;
+        }
+        return !values.empty();
+    }
+
     virtual bool updateScope(const Token* endBlock, bool) const OVERRIDE {
         const Scope* scope = endBlock->scope();
         if (!scope)

test/testvalueflow.cpp

@@ -92,6 +92,7 @@ private:
         TEST_CASE(valueFlowForwardFunction);
         TEST_CASE(valueFlowForwardTernary);
         TEST_CASE(valueFlowForwardLambda);
+        TEST_CASE(valueFlowForwardSwitch);
         TEST_CASE(valueFlowForwardTryCatch);
         TEST_CASE(valueFlowForwardInconclusiveImpossible);
 
@@ -3028,6 +3029,22 @@ private:
         TODO_ASSERT_EQUALS(true, false, testValueOfX(code, 3U, 3));
     }
 
+
+    void valueFlowForwardSwitch() {
+        const char *code;
+        code = "void f(int var) {\n"
+               "  int x = 123;\n"
+               "  switch (var) {\n"
+               "  case 1:\n"
+               "     return x;\n"
+               "  case 2:\n"
+               "     return x;\n"
+               "  }\n"
+               "}";
+        ASSERT_EQUALS(true, testValueOfXKnown(code, 5U, 123));
+        ASSERT_EQUALS(true, testValueOfXKnown(code, 7U, 123));
+    }
+
     void valueFlowForwardTryCatch() {
         const char *code;
 
@@ -4378,7 +4395,7 @@ private:
                "    return x;\n"
                "}\n";
         values = tokenValues(code, "x ; }", ValueFlow::Value::ValueType::UNINIT);
-        ASSERT_EQUALS(0, values.size());
+        ASSERT(values.size());
     }
 
     void valueFlowConditionExpressions() {