From 58eb644003630c3dba3d9c4656fe5c53e4d21944 Mon Sep 17 00:00:00 2001
From: Harald Scheidl <harald_scheidl@hotmail.com>
Date: Sat, 8 Oct 2016 01:57:09 +0200
Subject: [PATCH] Improved Check: Warn about number and char literals in
 boolean expressions (#7750)

---
 lib/checkcondition.cpp |  9 ++++++---
 lib/tokenize.cpp       | 12 ++++++------
 lib/tokenize.h         |  2 +-
 test/testcondition.cpp | 16 +++++++++++++++-
 4 files changed, 28 insertions(+), 11 deletions(-)

diff --git a/lib/checkcondition.cpp b/lib/checkcondition.cpp
index ede34d27a..0b29b74e0 100644
--- a/lib/checkcondition.cpp
+++ b/lib/checkcondition.cpp
@@ -975,7 +975,12 @@ void CheckCondition::alwaysTrueFalse()
     for (std::size_t i = 0; i < functions; ++i) {
         const Scope * scope = symbolDatabase->functionScopes[i];
         for (const Token* tok = scope->classStart->next(); tok != scope->classEnd; tok = tok->next()) {
-            if (!Token::Match(tok, "%comp%|!"))
+
+            const bool constValCond = Token::Match(tok->tokAt(-2), "if|while ( %num%|%char% )"); // just one number or char inside if|while
+            const bool constValExpr = Token::Match(tok, "%num%|%char%") && tok->astParent() && Token::Match(tok->astParent(),"&&|%oror%|?"); // just one number or char in boolean expression
+            const bool compExpr = Token::Match(tok, "%comp%|!"); // a compare expression
+
+            if (!(constValCond || constValExpr || compExpr))
                 continue;
             if (tok->link()) // don't write false positives when templates are used
                 continue;
@@ -983,8 +988,6 @@ void CheckCondition::alwaysTrueFalse()
                 continue;
             if (!tok->values.front().isKnown())
                 continue;
-            if (!tok->astParent() || !Token::Match(tok->astParent()->previous(), "%name% ("))
-                continue;
 
             // Don't warn in assertions. Condition is often 'always true' by intention.
             // If platform,defines,etc cause 'always false' then that is not dangerous neither.
diff --git a/lib/tokenize.cpp b/lib/tokenize.cpp
index 9f7732231..7ea58c03b 100644
--- a/lib/tokenize.cpp
+++ b/lib/tokenize.cpp
@@ -1859,14 +1859,14 @@ void Tokenizer::combineOperators()
     }
 }
 
-void Tokenizer::combineStrings()
+void Tokenizer::combineStringAndCharLiterals()
 {
-    // Combine wide strings
+    // Combine wide strings and wide characters
     for (Token *tok = list.front();
          tok;
          tok = tok->next()) {
-        while (tok->str() == "L" && tok->next() && tok->next()->tokType() == Token::eString) {
-            // Combine 'L "string"'
+        if (tok->str() == "L" && tok->next() && (tok->next()->tokType() == Token::eString || tok->next()->tokType() == Token::eChar)) {
+            // Combine 'L "string"' and 'L 'c''
             tok->str(tok->next()->str());
             tok->deleteNext();
             tok->isLong(true);
@@ -3326,8 +3326,8 @@ bool Tokenizer::simplifyTokenList1(const char FileName[])
     // remove MACRO in variable declaration: MACRO int x;
     removeMacroInVarDecl();
 
-    // Combine strings
-    combineStrings();
+    // Combine strings and character literals, e.g. L"string", L'c', "string1" "string2"
+    combineStringAndCharLiterals();
 
     // replace inline SQL with "asm()" (Oracle PRO*C). Ticket: #1959
     simplifySQL();
diff --git a/lib/tokenize.h b/lib/tokenize.h
index f6457abef..bf805e759 100644
--- a/lib/tokenize.h
+++ b/lib/tokenize.h
@@ -466,7 +466,7 @@ public:
 
     void combineOperators();
 
-    void combineStrings();
+    void combineStringAndCharLiterals();
 
     void simplifyNull();
 
diff --git a/test/testcondition.cpp b/test/testcondition.cpp
index 4c0143f19..4bdfb9b50 100644
--- a/test/testcondition.cpp
+++ b/test/testcondition.cpp
@@ -1552,7 +1552,8 @@ private:
         check("void f() {\n"
               "    if (x & 3 == 2) {}\n"
               "}");
-        ASSERT_EQUALS("[test.cpp:2]: (style) Suspicious condition (bitwise operator + comparison); Clarify expression with parentheses.\n", errout.str());
+        ASSERT_EQUALS("[test.cpp:2]: (style) Suspicious condition (bitwise operator + comparison); Clarify expression with parentheses.\n"
+                      "[test.cpp:2]: (style) Condition '3==2' is always false\n", errout.str());
 
         check("void f() {\n"
               "    if (a & fred1.x == fred2.y) {}\n"
@@ -1726,6 +1727,19 @@ private:
               "  assert(x == 0);\n"
               "}");
         ASSERT_EQUALS("", errout.str());
+
+        // #7750 warn about number and char literals in boolean expressions
+        check("void f() {\n"
+              "  if('a'){}\n"
+              "  if(L'b'){}\n"
+              "  if(1 && 'c'){}\n"
+              "  int x = 'd' ? 1 : 2;\n"
+              "}");
+        ASSERT_EQUALS("[test.cpp:2]: (style) Condition ''a'' is always true\n"
+                      "[test.cpp:3]: (style) Condition ''b'' is always true\n"
+                      "[test.cpp:4]: (style) Condition '1' is always true\n"
+                      "[test.cpp:4]: (style) Condition ''c'' is always true\n"
+                      "[test.cpp:5]: (style) Condition ''d'' is always true\n", errout.str());
     }
 
     void checkInvalidTestForOverflow() {