clang-tidy: Fix 'cppcoreguidelines-pro-type-member-init' warnings

Also, fix undefined behavior when setting and reading different field of
a union (Lexer, Token) - according to the C++ Standard, it is not
allowed to use a union to zero members of a struct.

Treat these warnings as errors now.

Change-Id: I0f6d071217ef55e2c75c51138fcff47048eca62f
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

6 files changed, 9 insertions, 26 deletions

diff --git a/src/plugins/scanner/cpp/Lexer.cpp b/src/plugins/scanner/cpp/Lexer.cpp
index 5bf5b2367..16556ac73 100644
--- a/src/plugins/scanner/cpp/Lexer.cpp
+++ b/src/plugins/scanner/cpp/Lexer.cpp
@@ -64,7 +64,6 @@ namespace CPlusPlus {
 
 Lexer::Lexer(const char *firstChar, const char *lastChar)
     : _state(State_Default),
-      _flags(0),
       _currentLine(1)
 {
     setSource(firstChar, lastChar);
diff --git a/src/plugins/scanner/cpp/Lexer.h b/src/plugins/scanner/cpp/Lexer.h
index 1cf829ebb..8f55f84e9 100644
--- a/src/plugins/scanner/cpp/Lexer.h
+++ b/src/plugins/scanner/cpp/Lexer.h
@@ -151,10 +151,7 @@ private:
     const char *_tokenStart = nullptr;
     unsigned char _yychar = 0;
     int _state = 0;
-    union {
-        unsigned _flags;
-        Flags f;
-    };
+    Flags f{};
     unsigned _currentLine = 0;
 };
 
diff --git a/src/plugins/scanner/cpp/Token.cpp b/src/plugins/scanner/cpp/Token.cpp
index 603918f63..b488bf0d4 100644
--- a/src/plugins/scanner/cpp/Token.cpp
+++ b/src/plugins/scanner/cpp/Token.cpp
@@ -113,16 +113,9 @@ static const char *token_names[] = {
 
 };
 
-Token::Token() :
-    flags(0), offset(0), ptr(nullptr)
-{
-}
-
-Token::~Token() = default;
-
 void Token::reset()
 {
-    flags = 0;
+    f = {};
     offset = 0;
     ptr = nullptr;
 }
diff --git a/src/plugins/scanner/cpp/Token.h b/src/plugins/scanner/cpp/Token.h
index 846aa5a12..a042c1087 100644
--- a/src/plugins/scanner/cpp/Token.h
+++ b/src/plugins/scanner/cpp/Token.h
@@ -295,9 +295,6 @@ enum Kind {
 class CPLUSPLUS_EXPORT Token
 {
 public:
-    Token();
-    ~Token();
-
     inline bool is(unsigned k) const    { return f.kind == k; }
     inline bool isNot(unsigned k) const { return f.kind != k; }
 #ifndef CPLUSPLUS_NO_PARSER
@@ -348,15 +345,12 @@ public:
         unsigned pad        : 3;
         unsigned length     : 16;
     };
-    union {
-        unsigned flags;
-        Flags f;
-    };
+    Flags f{};
 
     unsigned offset = 0;
 
     union {
-        void *ptr;
+        void *ptr = nullptr;
 #ifndef CPLUSPLUS_NO_PARSER
         const Literal *literal;
         const NumericLiteral *number;
diff --git a/src/plugins/scanner/cpp/cppscanner.cpp b/src/plugins/scanner/cpp/cppscanner.cpp
index 191a0f8d2..0acb25172 100644
--- a/src/plugins/scanner/cpp/cppscanner.cpp
+++ b/src/plugins/scanner/cpp/cppscanner.cpp
@@ -65,9 +65,9 @@ using namespace CPlusPlus;
 
 struct ScanResult
 {
-    char *fileName;
-    int size;
-    int flags;
+    char *fileName = nullptr;
+    int size = 0;
+    int flags = 0;
 };
 
 struct Opaq
@@ -226,7 +226,7 @@ static void *openScanner(const unsigned short *filePath, const char *fileTags, i
         return nullptr;
     }
 
-    struct stat s;
+    struct stat s{};
     int r = fstat(opaque->fd, &s);
     if (r != 0)
         return nullptr;
diff --git a/src/plugins/scanner/qt/qtscanner.cpp b/src/plugins/scanner/qt/qtscanner.cpp
index 22fdcb79d..22ef294d0 100644
--- a/src/plugins/scanner/qt/qtscanner.cpp
+++ b/src/plugins/scanner/qt/qtscanner.cpp
@@ -107,7 +107,7 @@ static void *openScannerQrc(const unsigned short *filePath, const char *fileTags
         return nullptr;
     }
 
-    struct stat s;
+    struct stat s{};
     int r = fstat(opaque->fd, &s);
     if (r != 0)
         return nullptr;