clang/gcc: enable a bunch more warnings (#91)

* clang/gcc: enable -pedantic warnings

* suppress a GCC-specific warning in stb_image

* And some clang-specific warnings

* -Wconversion (clang) -Wold-style-cast (clang+gcc)

and fix a few warnings that show up with these (and a few more with
-Wconversion on gcc, even though that's not enabled by default)

* bunch more warnings

* fixes

* remove merge error

src/utils/CMakeLists.txt

@@ -51,3 +51,7 @@ add_library(utils STATIC ${UTILS_SOURCES})
 target_link_libraries(utils nxt_backend shaderc nxtcpp nxt)
 target_include_directories(utils PUBLIC ${SRC_DIR})
 NXTInternalTarget("" utils)
+if(NOT MSVC)
+    # allow C-style casts -- for shaderc
+    set_property(TARGET utils APPEND PROPERTY COMPILE_OPTIONS "-Wno-old-style-cast")
+endif()

src/utils/NXTHelpers.cpp

@@ -50,8 +50,13 @@ namespace utils {
             return;
         }
 
-        size_t size = (result.cend() - result.cbegin());
-        builder.SetSource(static_cast<uint32_t>(size), result.cbegin());
+        // result.cend and result.cbegin return pointers to uint32_t.
+        const uint32_t* resultBegin = result.cbegin();
+        const uint32_t* resultEnd = result.cend();
+        // So this size is in units of sizeof(uint32_t).
+        ptrdiff_t resultSize = resultEnd - resultBegin;
+        // SetSource takes data as uint32_t*.
+        builder.SetSource(static_cast<uint32_t>(resultSize), result.cbegin());
 
 #ifdef DUMP_SPIRV_ASSEMBLY
         {

src/utils/SystemUtils.cpp

@@ -25,11 +25,11 @@
 namespace utils {
 
     #if defined(NXT_PLATFORM_WINDOWS)
-        void USleep(int usecs) {
+        void USleep(unsigned int usecs) {
             Sleep(static_cast<DWORD>(usecs / 1000));
         }
     #elif defined(NXT_PLATFORM_POSIX)
-        void USleep(int usecs) {
+        void USleep(unsigned int usecs) {
             usleep(usecs);
         }
     #else

src/utils/SystemUtils.h

@@ -14,6 +14,6 @@
 
 namespace utils {
 
-    void USleep(int usecs);
+    void USleep(unsigned int usecs);
 
 }