[meta] Declare bool conversion operators as explicit

Non-explicit conversion operators in general can participate in very
surprising conversion chains. Explicit bool operator is a good place to
start with, because even with explicit they do get automatic contextual
conversion in a lot of places, e.g., if conditions.

src/d3d9/d3d9_mem.h

@@ -81,7 +81,7 @@ namespace dxvk {
       D3D9Memory             (D3D9Memory&& other);
       D3D9Memory& operator = (D3D9Memory&& other);
 
-      operator bool() const { return m_chunk != nullptr; }
+      explicit operator bool() const { return m_chunk != nullptr; }
 
       void Map();
       void Unmap();
@@ -139,7 +139,7 @@ namespace dxvk {
       D3D9Memory             (D3D9Memory&& other);
       D3D9Memory& operator = (D3D9Memory&& other);
 
-      operator bool() const { return m_ptr != nullptr; }
+      explicit operator bool() const { return m_ptr != nullptr; }
 
       void Map() {}
       void Unmap() {}

src/d3d9/d3d9_state.h

@@ -195,7 +195,7 @@ namespace dxvk {
     const T* operator & () const { ensure(); return m_data.get(); }
           T* operator & ()       { ensure(); return m_data.get(); }
 
-    operator bool() { return m_data != nullptr; }
+    explicit operator bool() const { return m_data != nullptr; }
     operator T() { ensure(); return *m_data; }
 
     void ensure() const { if (!m_data) m_data = std::make_unique<T>(); }
@@ -213,7 +213,7 @@ namespace dxvk {
 
     T& operator=(const T& x) { m_data = x; return m_data; }
 
-    operator bool() { return true; }
+    explicit operator bool() const { return true; }
     operator T() { return m_data; }
 
     const T* operator -> () const { return &m_data; }

src/dxbc/dxbc_decoder.h

@@ -196,7 +196,7 @@ namespace dxvk {
       return out;
     }
 
-    operator bool () const {
+    explicit operator bool () const {
       return m_mask != 0;
     }
     

src/dxvk/dxvk_cs.h

@@ -350,7 +350,7 @@ namespace dxvk {
       return m_chunk;
     }
     
-    operator bool () const {
+    explicit operator bool () const {
       return m_chunk != nullptr;
     }
     

src/dxvk/dxvk_extensions.h

@@ -61,7 +61,7 @@ namespace dxvk {
      * provided by the extension can be used.
      * \returns \c true if the extension is enabled
      */
-    operator bool () const {
+    explicit operator bool () const {
       return m_revision != 0;
     }
 

src/dxvk/dxvk_memory.h

@@ -158,7 +158,7 @@ namespace dxvk {
      * \returns \c true if this slice points to actual device
      *          memory, and \c false if it is undefined.
      */
-    operator bool () const {
+    explicit operator bool () const {
       return m_memory != VK_NULL_HANDLE;
     }
     

src/dxvk/dxvk_sparse.h

@@ -239,7 +239,7 @@ namespace dxvk {
       return m_page != other.m_page;
     }
 
-    operator bool () const {
+    explicit operator bool () const {
       return m_page != nullptr;
     }
 
@@ -341,7 +341,7 @@ namespace dxvk {
      * \brief Checks whether page table is defined
      * \returns \c true if the page table is defined
      */
-    operator bool () const {
+    explicit operator bool () const {
       return m_buffer || m_image;
     }