From 9f2ddf1623e29c6c30055c30b2651cabeb0ed878 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Marjam=C3=A4ki?= <daniel.marjamaki@gmail.com>
Date: Sun, 3 Oct 2021 14:47:21 +0200
Subject: [PATCH] UninitVar: too many warnings (function/cast operand)

---
 lib/checkuninitvar.cpp  |  2 +-
 lib/forwardanalyzer.cpp | 12 +++++++++++-
 test/testvalueflow.cpp  | 30 ++++++++++++++++++++++++++++++
 3 files changed, 42 insertions(+), 2 deletions(-)

diff --git a/lib/checkuninitvar.cpp b/lib/checkuninitvar.cpp
index 4ff956518..579594ec6 100644
--- a/lib/checkuninitvar.cpp
+++ b/lib/checkuninitvar.cpp
@@ -50,7 +50,7 @@ namespace {
 
 //---------------------------------------------------------------------------
 
-static bool isSizeOfEtc(const Token *tok)
+bool isSizeOfEtc(const Token *tok)
 {
     return Token::Match(tok, "sizeof|typeof|offsetof|decltype|__typeof__ (");
 }
diff --git a/lib/forwardanalyzer.cpp b/lib/forwardanalyzer.cpp
index bdf648110..d050f84e3 100644
--- a/lib/forwardanalyzer.cpp
+++ b/lib/forwardanalyzer.cpp
@@ -12,6 +12,8 @@
 #include <tuple>
 #include <utility>
 
+bool isSizeOfEtc(const Token *tok);
+
 struct OnExit {
     std::function<void()> f;
 
@@ -192,8 +194,16 @@ struct ForwardTraversal {
     Progress update(Token* tok) {
         Analyzer::Action action = analyzer->analyze(tok, Analyzer::Direction::Forward);
         actions |= action;
-        if (!action.isNone() && !analyzeOnly)
+        if (!action.isNone() && !analyzeOnly) {
             analyzer->update(tok, action, Analyzer::Direction::Forward);
+
+            // uninit value => skip further analysis
+            auto v = std::find_if(tok->values().begin(), tok->values().end(), std::mem_fn(&ValueFlow::Value::isUninitValue));
+            if (v != tok->values().end()) {
+                if (Token::Match(tok->astParent(), "[,(]") && !isSizeOfEtc(tok->astParent()->previous()))
+                    return Break(Analyzer::Terminate::Modified);
+            }
+        }
         if (action.isInconclusive() && !analyzer->lowerToInconclusive())
             return Break(Analyzer::Terminate::Inconclusive);
         if (action.isInvalid())
diff --git a/test/testvalueflow.cpp b/test/testvalueflow.cpp
index 12366df42..04f347782 100644
--- a/test/testvalueflow.cpp
+++ b/test/testvalueflow.cpp
@@ -120,6 +120,7 @@ private:
         TEST_CASE(valueFlowSameExpression);
 
         TEST_CASE(valueFlowUninit);
+        TEST_CASE(valueFlowUninitBreak);
 
         TEST_CASE(valueFlowConditionExpressions);
 
@@ -4651,6 +4652,35 @@ private:
         ASSERT_EQUALS(0, values.size());
     }
 
+    void valueFlowUninitBreak() { // break uninit analysis to avoid extra warnings
+        const char *code;
+        std::list<ValueFlow::Value> values;
+
+        code = "struct wcsstruct {\n"
+               "    int *wcsprm;\n"
+               "};\n"
+               "\n"
+               "void copy_wcs(wcsstruct *wcsin) {\n"
+               "   wcsstruct *x;\n"
+               "   memcpy(wcsin, x, sizeof(wcsstruct));\n" // <- True positive
+               "   x->wcsprm = NULL;\n" // <- False positive
+               "}";
+        values = tokenValues(code, "x . wcsprm", ValueFlow::Value::ValueType::UNINIT);
+        ASSERT_EQUALS(0, values.size());
+
+        code = "struct wcsstruct {\n"
+               "    int *wcsprm;\n"
+               "};\n"
+               "\n"
+               "void copy_wcs(wcsstruct *wcsin) {\n"
+               "   wcsstruct *x;\n"
+               "   sizeof(x);\n"
+               "   x->wcsprm = NULL;\n" // <- Warn
+               "}";
+        values = tokenValues(code, "x . wcsprm", ValueFlow::Value::ValueType::UNINIT);
+        ASSERT_EQUALS(1, values.size());
+    }
+
     void valueFlowConditionExpressions() {
         const char* code;