From 4746d4b8190701e25777ee2b771777f3d30e575f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Marjam=C3=A4ki?= <daniel.marjamaki@gmail.com>
Date: Thu, 20 May 2021 22:56:14 +0200
Subject: [PATCH] Uninitialized variables; Improved checking of loops

---
 lib/checkuninitvar.cpp | 27 ++++++++++++++++++++-------
 test/testuninitvar.cpp | 25 +++++++++++++++++++++++++
 2 files changed, 45 insertions(+), 7 deletions(-)

diff --git a/lib/checkuninitvar.cpp b/lib/checkuninitvar.cpp
index 388ed4964..11daa14dd 100644
--- a/lib/checkuninitvar.cpp
+++ b/lib/checkuninitvar.cpp
@@ -891,6 +891,14 @@ const Token* CheckUninitVar::checkLoopBodyRecursive(const Token *start, const Va
         if (tok->varId() != var.declarationId())
             continue;
 
+        bool conditionalUsage = false;
+        for (const Token* parent = tok; parent; parent = parent->astParent()) {
+            if (Token::Match(parent->astParent(), "%oror%|&&|?") && astIsRHS(parent)) {
+                conditionalUsage = true;
+                break;
+            }
+        }
+
         if (!membervar.empty()) {
             if (isMemberVariableAssignment(tok, membervar)) {
                 bool assign = true;
@@ -924,17 +932,22 @@ const Token* CheckUninitVar::checkLoopBodyRecursive(const Token *start, const Va
                     return nullptr;
                 }
             }
-
-            if (isMemberVariableUsage(tok, var.isPointer(), alloc, membervar))
-                return tok;
-            else if (Token::Match(tok->previous(), "[(,] %name% [,)]")) {
+            if (isMemberVariableUsage(tok, var.isPointer(), alloc, membervar)) {
+                if (!conditionalUsage)
+                    return tok;
+                if (!errorToken)
+                    errorToken = tok;
+            } else if (Token::Match(tok->previous(), "[(,] %name% [,)]")) {
                 bailout = true;
                 return nullptr;
             }
         } else {
-            if (const Token *errtok = isVariableUsage(tok, var.isPointer(), alloc))
-                return errtok;
-            else if (tok->strAt(1) == "=") {
+            if (const Token *errtok = isVariableUsage(tok, var.isPointer(), alloc)) {
+                if (!conditionalUsage)
+                    return errtok;
+                if (!errorToken)
+                    errorToken = errtok;
+            } else if (tok->strAt(1) == "=") {
                 bool varIsUsedInRhs = false;
                 visitAstNodes(tok->next()->astOperand2(), [&](const Token * t) {
                     if (!t)
diff --git a/test/testuninitvar.cpp b/test/testuninitvar.cpp
index 0ec8e16c6..80afd7b30 100644
--- a/test/testuninitvar.cpp
+++ b/test/testuninitvar.cpp
@@ -1233,6 +1233,31 @@ private:
                        "}");
         ASSERT_EQUALS("", errout.str());
 
+        checkUninitVar("void foo(void) {\n"
+                       "    int a = 0;\n"
+                       "    int x;\n"
+                       "\n"
+                       "    for (;;) {\n"
+                       "        if (!a || 12 < x) {\n" // <- x is not uninitialized
+                       "            a = 1;\n"
+                       "            x = 2;\n"
+                       "        }\n"
+                       "    }\n"
+                       "}");
+        ASSERT_EQUALS("", errout.str());
+
+        checkUninitVar("void foo(void) {\n"
+                       "    int a = 0;\n"
+                       "    int x;\n"
+                       "\n"
+                       "    for (;;) {\n"
+                       "        if (!a || 12 < x) {\n" // <- x is uninitialized
+                       "            a = 1;\n"
+                       "        }\n"
+                       "    }\n"
+                       "}");
+        ASSERT_EQUALS("[test.cpp:6]: (error) Uninitialized variable: x\n", errout.str());
+
         // Ticket #2226: C++0x loop
         checkUninitVar("void f() {\n"
                        "    container c;\n"