DebugTools: make bufferSubData()'s template type default to char

This is already done for bufferData()

src/Magnum/DebugTools/BufferData.h

@@ -59,7 +59,7 @@ WebGL 2.0 it's just an alias to @ref GL::Buffer::subData().
 @requires_webgl20 Buffer data queries or buffer mapping are not available in
     WebGL 1.0.
 */
-template<class T> Containers::Array<T> inline bufferSubData(GL::Buffer& buffer, GLintptr offset, GLsizeiptr size) {
+template<class T = char> Containers::Array<T> inline bufferSubData(GL::Buffer& buffer, GLintptr offset, GLsizeiptr size) {
     if(!size) return {};
     #if !defined(MAGNUM_TARGET_GLES) || defined(MAGNUM_TARGET_WEBGL)
     Containers::Array<char> data = buffer.subData(offset, size*sizeof(T));

src/Magnum/DebugTools/Test/BufferDataGLTest.cpp

@@ -59,9 +59,15 @@ void BufferDataGLTest::data() {
     CORRADE_VERIFY(emptyContents.isEmpty());
 
     buffer.setData(Data, GL::BufferUsage::StaticDraw);
-    const Containers::Array<Int> contents = bufferData<Int>(buffer);
+
+    const Containers::Array<char> contents = bufferData(buffer);
+    MAGNUM_VERIFY_NO_GL_ERROR();
+    CORRADE_COMPARE_AS(contents,
+        Containers::arrayCast<const char>(Containers::arrayView(Data)),
+        TestSuite::Compare::Container);
+    const Containers::Array<Int> intContents = bufferData<Int>(buffer);
     MAGNUM_VERIFY_NO_GL_ERROR();
-    CORRADE_COMPARE_AS(contents, Containers::arrayView(Data),
+    CORRADE_COMPARE_AS(intContents, Containers::arrayView(Data),
         TestSuite::Compare::Container);
 }
 
@@ -73,11 +79,16 @@ void BufferDataGLTest::subData() {
 
     GL::Buffer buffer;
     buffer.setData(Data, GL::BufferUsage::StaticDraw);
-    const Containers::Array<Int> contents = bufferSubData<Int>(buffer, 4, 3);
+
+    const Containers::Array<char> contents = bufferSubData(buffer, 4, 3*4);
     MAGNUM_VERIFY_NO_GL_ERROR();
-    CORRADE_COMPARE_AS(contents, Containers::arrayView(Data).slice(1, 4),
+    CORRADE_COMPARE_AS(contents,
+        Containers::arrayCast<const char>(Containers::arrayView(Data).slice(1, 4)),
+        TestSuite::Compare::Container);
+    const Containers::Array<Int> intContents = bufferSubData<Int>(buffer, 4, 3);
+    MAGNUM_VERIFY_NO_GL_ERROR();
+    CORRADE_COMPARE_AS(intContents, Containers::arrayView(Data).slice(1, 4),
         TestSuite::Compare::Container);
-
     const Containers::Array<Int> emptyContents = bufferSubData<Int>(buffer, 4, 0);
     MAGNUM_VERIFY_NO_GL_ERROR();
     CORRADE_VERIFY(emptyContents.isEmpty());