fix #13954: Unnamed bit fields are removed.

lib/checkclass.cpp

@@ -231,6 +231,9 @@ void CheckClass::constructors()
                 if (usage.assign || usage.init || var.isStatic())
                     continue;
 
+                if (var.nameToken() && var.nameToken()->isAnonymousBitfield())
+                    continue;
+
                 if (var.valueType() && var.valueType()->pointer == 0 && var.type() && var.type()->needInitialization == Type::NeedInitialization::False && var.type()->derivedFrom.empty())
                     continue;
 

lib/checkunusedvar.cpp

@@ -1575,6 +1575,9 @@ void CheckUnusedVar::checkStructMemberUsage()
             if (isInherited && !var.isPrivate())
                 continue;
 
+            if (var.nameToken() && (var.nameToken()->isAttributeUnused() || var.nameToken()->isAnonymousBitfield()))
+                continue;
+
             if (mTokenizer->isVarUsedInTemplate(var.declarationId()))
                 continue;
 

lib/token.h

@@ -742,6 +742,13 @@ class CPPCHECKLIB Token {
         setFlag(fIsInitBracket, b);
     }
 
+    bool isAnonymousBitfield() const {
+        return getFlag(fIsAnonymousBitfield);
+    }
+    void isAnonymousBitfield(bool b) {
+        setFlag(fIsAnonymousBitfield, b);
+    }
+
     // cppcheck-suppress unusedFunction
     bool isBitfield() const {
         return mImpl->mBits > 0;
@@ -1426,6 +1433,7 @@ class CPPCHECKLIB Token {
         fIsFinalType            = (1ULL << 42), // Is this a type with final specifier
         fIsInitComma            = (1ULL << 43), // Is this comma located inside some {..}. i.e: {1,2,3,4}
         fIsInitBracket          = (1ULL << 44), // Is this bracket used as a part of variable initialization i.e: int a{5}, b(2);
+        fIsAnonymousBitfield    = (1ULL << 45), // Is this a token added for an unnamed bit-field
     };
 
     enum : std::uint8_t {

lib/tokenize.cpp

@@ -9985,12 +9985,8 @@ void Tokenizer::simplifyAt()
 // Simplify bitfields
 void Tokenizer::simplifyBitfields()
 {
-    bool goback = false;
+    std::size_t anonymousBitfieldCounter = 0;
     for (Token *tok = list.front(); tok; tok = tok->next()) {
-        if (goback) {
-            goback = false;
-            tok = tok->previous();
-        }
         Token *last = nullptr;
 
         if (Token::simpleMatch(tok, "for ("))
@@ -10040,8 +10036,15 @@ void Tokenizer::simplifyBitfields()
             }
         } else if (Token::Match(typeTok, "%type% : %num%|%bool% ;") &&
                    typeTok->str() != "default") {
-            tok->deleteNext(4 + tokDistance(tok, typeTok) - 1);
-            goback = true;
+            const std::size_t id = anonymousBitfieldCounter++;
+            const std::string name = "__cppcheck_anon_bit_field_" + std::to_string(id) + "__";
+            Token *newTok = typeTok->insertToken(name);
+            newTok->isAnonymousBitfield(true);
+            if (newTok->tokAt(2)->isBoolean())
+                newTok->setBits(static_cast<unsigned char>(newTok->strAt(2) == "true"));
+            else
+                newTok->setBits(static_cast<unsigned char>(MathLib::toBigNumber(newTok->tokAt(2))));
+            newTok->deleteNext(2);
         }
 
         if (last && last->str() == ",") {

test/testconstructors.cpp

@@ -172,6 +172,7 @@ class TestConstructors : public TestFixture {
         TEST_CASE(uninitVar33); // ticket #10295
         TEST_CASE(uninitVar34); // ticket #10841
         TEST_CASE(uninitVar35);
+        TEST_CASE(uninitVar36);
         TEST_CASE(uninitVarEnum1);
         TEST_CASE(uninitVarEnum2); // ticket #8146
         TEST_CASE(uninitVarStream);
@@ -3020,6 +3021,16 @@ class TestConstructors : public TestFixture {
         ASSERT_EQUALS("", errout_str());
     }
 
+    void uninitVar36() {
+        check("struct S {\n"
+              "    unsigned int a : 16;\n"
+              "    unsigned int   : 8;\n"
+              "    unsigned int b : 8;\n"
+              "    S() : a(0) {}\n"
+              "};\n");
+        ASSERT_EQUALS("[test.cpp:5:5]: (warning) Member variable 'S::b' is not initialized in the constructor. [uninitMemberVar]\n", errout_str());
+    }
+
     void uninitVarArray1() {
         check("class John\n"
               "{\n"

test/testtokenize.cpp

@@ -4724,7 +4724,7 @@ class TestTokenizer : public TestFixture {
         ASSERT_EQUALS("struct RGB { unsigned int r ; unsigned int g ; unsigned int b ; } ;", tokenizeAndStringify(code1));
 
         const char code2[] = "struct A { int a : 3; int : 3; int c : 3; };";
-        ASSERT_EQUALS("struct A { int a ; int c ; } ;", tokenizeAndStringify(code2));
+        ASSERT_EQUALS("struct A { int a ; int __cppcheck_anon_bit_field_0__ ; int c ; } ;", tokenizeAndStringify(code2));
 
         const char code3[] = "struct A { virtual void f() {} int f1 : 1; };";
         ASSERT_EQUALS("struct A { virtual void f ( ) { } int f1 ; } ;", tokenizeAndStringify(code3));
@@ -4738,7 +4738,7 @@ class TestTokenizer : public TestFixture {
         ASSERT_EQUALS("struct A { bool b ; bool c ; } ;", tokenizeAndStringify(code2));
 
         const char code3[] = "struct A { bool : true; };";
-        ASSERT_EQUALS("struct A { } ;", tokenizeAndStringify(code3));
+        ASSERT_EQUALS("struct A { bool __cppcheck_anon_bit_field_0__ ; } ;", tokenizeAndStringify(code3));
     }
 
     void bitfields7() { // ticket #1987
@@ -4789,7 +4789,7 @@ class TestTokenizer : public TestFixture {
 
     void bitfields12() { // ticket #3485 (segmentation fault)
         const char code[] = "{a:1;};\n";
-        ASSERT_EQUALS("{ } ;", tokenizeAndStringify(code));
+        ASSERT_EQUALS("{ a __cppcheck_anon_bit_field_0__ ; } ;", tokenizeAndStringify(code));
     }
 
     void bitfields13() { // ticket #3502 (segmentation fault)
@@ -4829,9 +4829,9 @@ class TestTokenizer : public TestFixture {
                             "};\n";
         const char expected[] = "struct S {\n"
                                 "volatile uint32_t a ;\n"
-                                "\n"
+                                "volatile uint32_t __cppcheck_anon_bit_field_0__ ;\n"
                                 "volatile uint32_t b ;\n"
-                                "\n"
+                                "volatile uint32_t __cppcheck_anon_bit_field_1__ ;\n"
                                 "} ;";
         ASSERT_EQUALS(expected, tokenizeAndStringify(code));
 
@@ -4841,7 +4841,7 @@ class TestTokenizer : public TestFixture {
                              "};\n";
         const char expected2[] = "struct S {\n"
                                  "const volatile uint32_t a ;\n"
-                                 "\n"
+                                 "const volatile uint32_t __cppcheck_anon_bit_field_0__ ;\n"
                                  "} ;";
         ASSERT_EQUALS(expected2, tokenizeAndStringify(code2));
     }

test/testunusedvar.cpp

@@ -70,6 +70,7 @@ class TestUnusedVar : public TestFixture {
         TEST_CASE(structmember25);
         TEST_CASE(structmember26); // #13345
         TEST_CASE(structmember27); // #13367
+        TEST_CASE(structmember28);
         TEST_CASE(structmember_macro);
         TEST_CASE(structmember_template_argument); // #13887 - do not report that member used in template argument is unused
         TEST_CASE(classmember);
@@ -1998,6 +1999,14 @@ class TestUnusedVar : public TestFixture {
                       errout_str());
     }
 
+    void structmember28() {
+        checkStructMemberUsage("struct S {\n"
+                               "    unsigned int a : 16;\n"
+                               "    unsigned int : 16;\n"
+                               "};\n");
+        ASSERT_EQUALS("[test.cpp:2:18]: (style) struct member 'S::a' is never used. [unusedStructMember]\n", errout_str());
+    }
+
     void structmember_macro() {
         checkStructMemberUsageP("#define S(n) struct n { int a, b, c; };\n"
                                 "S(unused);\n");

test/testvalueflow.cpp

@@ -9105,6 +9105,10 @@ class TestValueFlow : public TestFixture {
                       "int b : 16;\n"
                       "unsigned short c;\n",
                       8);
+
+        testBitfields("unsigned int a : 31;\n"
+                      "unsigned int   : 2;\n",
+                      8);
     }
 };