GL: port label() / setLabel() away from std::string.

All the tests were updated to explicitly check that non-null-terminated
strings get handled properly (the GL label APIs have an  explicit size,
so it *should*, but just in case). Also, because various subclasses
override the setter to return correct type for method chaining and the
override has to be deinlined to avoid relying on a StringView include,
the tests are now explicitly done for each leaf class, instead of the
subclass

The <string> being removed from the base class for all GL objects may
affect downstream projects which relied on it being included. In case of
Magnum, the breakages were already fixed in the previous commit.

Compile time improvement for the MagnumGL library alone is 0.2 second or
4% (6.1 seconds before, 5.9 after). Not bad, given that there's three
more files to compile and strings are still heavily used in other GL
debug output APIs and all shader stuff. For a build of just the GL
library and all tests, it goes down from 28.9 seconds to 28.1. Most
tests also still rely quite heavily on std::stringstream for debug
output testing, so the numbers still could go further.

doc/changelog.dox

@@ -892,20 +892,27 @@ See also:
     @ref Corrade::Containers::ArrayView are now removed. This should have a
     significant positive effect on compile times of code using the @ref GL,
     @ref Audio, @ref Trade and @ref Text libraries
--   As part of the ongoing STL header dependency cleanup,
-    @ref GL::Context::vendorString(),
-    @relativeref{GL::Context,rendererString()},
-    @relativeref{GL::Context,versionString()},
-    @relativeref{GL::Context,shadingLanguageVersionString()},
-    @relativeref{GL::Context,shadingLanguageVersionStrings()} and
-    @relativeref{GL::Context,extensionStrings()} now return
-    @relativeref{Corrade,Containers::StringView} or a
-    @relativeref{Corrade,Containers::Array} /
-    @relativeref{Corrade,Containers::ArrayView} of them, instead of a
-    @ref std::string and a @ref std::vector. For at least some backwards
-    compatibility the @ref Corrade/Containers/StringStl.h header is included to
-    provide implicit conversions to a @ref std::string, but in most cases
-    you'll be forced to change the code that uses those APIs.
+-   As part of the ongoing STL header dependency cleanup, the following
+    breaking changes related to @ref std::string and a @ref std::vector are
+    done:
+    -   @ref GL::Context::vendorString(),
+        @relativeref{GL::Context,rendererString()},
+        @relativeref{GL::Context,versionString()},
+        @relativeref{GL::Context,shadingLanguageVersionString()},
+        @relativeref{GL::Context,shadingLanguageVersionStrings()} and
+        @relativeref{GL::Context,extensionStrings()} now return
+        @relativeref{Corrade,Containers::StringView} or a
+        @relativeref{Corrade,Containers::Array} /
+        @relativeref{Corrade,Containers::ArrayView} of them, instead of a
+        @ref std::string and a @ref std::vector.
+    -   All @ref GL::Buffer::label() "label()" and
+        @ref GL::Buffer::setLabel() "setLabel()" APIs now work with a
+        @relativeref{Corrade,Containers::StringView} /
+        @relativeref{Corrade,Containers::String} instead of a @ref std::string
+    To handle most backwards compatibility, @ref Corrade/Containers/StringStl.h
+    is included in affected headers for implicit conversions from/to a
+    @ref std::string, but in some cases you may be forced to change the code
+    that uses those APIs.
 -   @ref GL::TextureFormat::SR8 and @ref GL::TextureFormat::SRG8 were present
     on ES2 builds by mistake --- the @gl_extension{EXT,texture_sRGB_R8} and
     @gl_extension{EXT,texture_sRGB_RG8} extensions require OpenGL ES 3.0 at

src/Magnum/GL/AbstractFramebuffer.h

@@ -29,6 +29,7 @@
  * @brief Class @ref Magnum::GL::AbstractFramebuffer, enum @ref Magnum::GL::FramebufferClear, @ref Magnum::GL::FramebufferBlit, @ref Magnum::GL::FramebufferBlitFilter, @ref Magnum::GL::FramebufferTarget, enum set @ref Magnum::GL::FramebufferClearMask
  */
 
+#include <utility> /* std::swap() */
 #include <Corrade/Containers/EnumSet.h>
 
 #include "Magnum/GL/GL.h"

src/Magnum/GL/AbstractObject.cpp

@@ -27,6 +27,9 @@
 
 #include <Corrade/Utility/Assert.h>
 #include <Corrade/Containers/ArrayView.h>
+#ifndef MAGNUM_TARGET_WEBGL
+#include <Corrade/Containers/String.h>
+#endif
 
 #include "Magnum/GL/Context.h"
 #include "Magnum/GL/Extensions.h"
@@ -123,77 +126,65 @@ Int AbstractObject::maxLabelLength() {
     return value;
 }
 
-void AbstractObject::labelImplementationNoOp(GLenum, GLuint, Containers::ArrayView<const char>) {}
+void AbstractObject::labelImplementationNoOp(GLenum, GLuint, Containers::StringView) {}
 
 #ifndef MAGNUM_TARGET_GLES2
-void AbstractObject::labelImplementationKhrDesktopES32(const GLenum identifier, const GLuint name, const Containers::ArrayView<const char> label) {
-    glObjectLabel(identifier, name, label.size(), label);
+void AbstractObject::labelImplementationKhrDesktopES32(const GLenum identifier, const GLuint name, const Containers::StringView label) {
+    glObjectLabel(identifier, name, label.size(), label.data());
 }
 #endif
 
 #ifdef MAGNUM_TARGET_GLES
-void AbstractObject::labelImplementationKhrES(const GLenum identifier, const GLuint name, const Containers::ArrayView<const char> label) {
-    glObjectLabelKHR(identifier, name, label.size(), label);
+void AbstractObject::labelImplementationKhrES(const GLenum identifier, const GLuint name, const Containers::StringView label) {
+    glObjectLabelKHR(identifier, name, label.size(), label.data());
 }
 #endif
 
-void AbstractObject::labelImplementationExt(const GLenum identifier, const GLuint name, const Containers::ArrayView<const char> label) {
+void AbstractObject::labelImplementationExt(const GLenum identifier, const GLuint name, const Containers::StringView label) {
     const GLenum type = extTypeFromKhrIdentifier(identifier);
-    glLabelObjectEXT(type, name, label.size(), label);
+    glLabelObjectEXT(type, name, label.size(), label.data());
 }
 
-std::string AbstractObject::getLabelImplementationNoOp(GLenum, GLuint) { return  {}; }
+Containers::String AbstractObject::getLabelImplementationNoOp(GLenum, GLuint) { return  {}; }
 
 #ifndef MAGNUM_TARGET_GLES2
-std::string AbstractObject::getLabelImplementationKhrDesktopES32(const GLenum identifier, const GLuint name) {
+Containers::String AbstractObject::getLabelImplementationKhrDesktopES32(const GLenum identifier, const GLuint name) {
     /* Get label size (w/o null terminator). Specifying 0 as size is not
        allowed, thus we pass the maximum instead. */
     GLsizei size = 0;
     glGetObjectLabel(identifier, name, maxLabelLength(), &size, nullptr);
 
-    /* Make place also for the null terminator */
-    std::string label;
-    label.resize(size+1);
-    glGetObjectLabel(identifier, name, size+1, nullptr, &label[0]);
-
-    /* Pop null terminator and return the string */
-    label.resize(size);
+    /* The storage already includes the null terminator */
+    Containers::String label{NoInit, std::size_t(size)};
+    glGetObjectLabel(identifier, name, size+1, nullptr, label.data());
     return label;
 }
 #endif
 
 #ifdef MAGNUM_TARGET_GLES
-std::string AbstractObject::getLabelImplementationKhrES(const GLenum identifier, const GLuint name) {
+Containers::String AbstractObject::getLabelImplementationKhrES(const GLenum identifier, const GLuint name) {
     /* Get label size (w/o null terminator). Specifying 0 as size is not
        allowed, thus we pass the maximum instead. */
     GLsizei size = 0;
     glGetObjectLabelKHR(identifier, name, maxLabelLength(), &size, nullptr);
 
-    /* Make place also for the null terminator */
-    std::string label;
-    label.resize(size+1);
-    glGetObjectLabelKHR(identifier, name, size+1, nullptr, &label[0]);
-
-    /* Pop null terminator and return the string */
-    label.resize(size);
+    /* The storage already includes the null terminator */
+    Containers::String label{NoInit, std::size_t(size)};
+    glGetObjectLabelKHR(identifier, name, size+1, nullptr, label.data());
     return label;
 }
 #endif
 
-std::string AbstractObject::getLabelImplementationExt(const GLenum identifier, const GLuint name) {
-    GLsizei size = 0;
+Containers::String AbstractObject::getLabelImplementationExt(const GLenum identifier, const GLuint name) {
+    const GLenum type = extTypeFromKhrIdentifier(identifier);
 
     /* Get label size (w/o null terminator) */
-    const GLenum type = extTypeFromKhrIdentifier(identifier);
+    GLsizei size = 0;
     glGetObjectLabelEXT(type, name, 0, &size, nullptr);
 
-    /* Make place also for the null terminator */
-    std::string label;
-    label.resize(size+1);
-    glGetObjectLabelEXT(type, name, size+1, nullptr, &label[0]);
-
-    /* Pop null terminator and return the string */
-    label.resize(size);
+    /* The storage already includes the null terminator */
+    Containers::String label{NoInit, std::size_t(size)};
+    glGetObjectLabelEXT(type, name, size+1, nullptr, label.data());
     return label;
 }
 #endif

src/Magnum/GL/AbstractObject.h

@@ -29,13 +29,18 @@
  * @brief Class @ref Magnum::GL::AbstractObject
  */
 
-#include <string>
 #include <Corrade/Containers/EnumSet.h>
 
 #include "Magnum/Magnum.h"
 #include "Magnum/GL/OpenGL.h"
 #include "Magnum/GL/visibility.h"
 
+#ifdef MAGNUM_BUILD_DEPRECATED
+/* For the label stuff that used to be a std::string. Won't cover all cases but
+   should be sufficient. */
+#include <Corrade/Containers/StringStl.h>
+#endif
+
 namespace Magnum { namespace GL {
 
 namespace Implementation { struct DebugState; }
@@ -112,21 +117,21 @@ class MAGNUM_GL_EXPORT AbstractObject {
 
     private:
         #ifndef MAGNUM_TARGET_WEBGL
-        static MAGNUM_GL_LOCAL void labelImplementationNoOp(GLenum, GLuint, Containers::ArrayView<const char> label);
-        static MAGNUM_GL_LOCAL void labelImplementationExt(GLenum identifier, GLuint name, Containers::ArrayView<const char> label);
+        static MAGNUM_GL_LOCAL void labelImplementationNoOp(GLenum, GLuint, Containers::StringView label);
+        static MAGNUM_GL_LOCAL void labelImplementationExt(GLenum identifier, GLuint name, Containers::StringView label);
         #ifndef MAGNUM_TARGET_GLES2
-        static MAGNUM_GL_LOCAL void labelImplementationKhrDesktopES32(GLenum identifier, GLuint name, Containers::ArrayView<const char> label);
+        static MAGNUM_GL_LOCAL void labelImplementationKhrDesktopES32(GLenum identifier, GLuint name, Containers::StringView label);
         #endif
         #ifdef MAGNUM_TARGET_GLES
-        static MAGNUM_GL_LOCAL void labelImplementationKhrES(GLenum identifier, GLuint name, Containers::ArrayView<const char> label);
+        static MAGNUM_GL_LOCAL void labelImplementationKhrES(GLenum identifier, GLuint name, Containers::StringView label);
         #endif
-        static MAGNUM_GL_LOCAL std::string getLabelImplementationNoOp(GLenum, GLuint);
-        static MAGNUM_GL_LOCAL std::string getLabelImplementationExt(GLenum identifier, GLuint name);
+        static MAGNUM_GL_LOCAL Containers::String getLabelImplementationNoOp(GLenum, GLuint);
+        static MAGNUM_GL_LOCAL Containers::String getLabelImplementationExt(GLenum identifier, GLuint name);
         #ifndef MAGNUM_TARGET_GLES2
-        static MAGNUM_GL_LOCAL std::string getLabelImplementationKhrDesktopES32(GLenum identifier, GLuint name);
+        static MAGNUM_GL_LOCAL Containers::String getLabelImplementationKhrDesktopES32(GLenum identifier, GLuint name);
         #endif
         #ifdef MAGNUM_TARGET_GLES
-        static MAGNUM_GL_LOCAL std::string getLabelImplementationKhrES(GLenum identifier, GLuint name);
+        static MAGNUM_GL_LOCAL Containers::String getLabelImplementationKhrES(GLenum identifier, GLuint name);
         #endif
         #endif
 };

src/Magnum/GL/AbstractQuery.cpp

@@ -25,6 +25,9 @@
 
 #include "AbstractQuery.h"
 
+#ifndef MAGNUM_TARGET_WEBGL
+#include <Corrade/Containers/String.h>
+#endif
 #include <Corrade/Utility/Assert.h>
 
 #include "Magnum/GL/Context.h"
@@ -91,15 +94,15 @@ void AbstractQuery::createImplementationDSAExceptPipelineStats() {
 #endif
 
 #ifndef MAGNUM_TARGET_WEBGL
-std::string AbstractQuery::label() const {
+Containers::String AbstractQuery::label() const {
     #ifndef MAGNUM_TARGET_GLES2
     return Context::current().state().debug.getLabelImplementation(GL_QUERY, _id);
     #else
     return Context::current().state().debug.getLabelImplementation(GL_QUERY_KHR, _id);
     #endif
 }
 
-AbstractQuery& AbstractQuery::setLabelInternal(const Containers::ArrayView<const char> label) {
+AbstractQuery& AbstractQuery::setLabel(const Containers::StringView label) {
     #ifndef MAGNUM_TARGET_GLES2
     Context::current().state().debug.labelImplementation(GL_QUERY, _id, label);
     #else

src/Magnum/GL/AbstractQuery.h

@@ -29,6 +29,7 @@
  * @brief Class @ref Magnum::GL::AbstractQuery
  */
 
+#include <utility> /* std::swap() */
 #include <Corrade/Containers/ArrayView.h>
 #include <Corrade/Utility/Assert.h>
 
@@ -37,6 +38,12 @@
 
 #include "Magnum/configure.h"
 
+#ifdef MAGNUM_BUILD_DEPRECATED
+/* For label() / setLabel(), which used to be a std::string. Not ideal for the
+   return type, but at least something. */
+#include <Corrade/Containers/StringStl.h>
+#endif
+
 namespace Magnum { namespace GL {
 
 namespace Implementation { struct QueryState; }
@@ -93,7 +100,7 @@ class MAGNUM_GL_EXPORT AbstractQuery: public AbstractObject {
          *      @def_gl{QUERY_OBJECT_EXT}
          * @requires_gles Debug output is not available in WebGL.
          */
-        std::string label() const;
+        Containers::String label() const;
 
         /**
          * @brief Set query label
@@ -108,14 +115,7 @@ class MAGNUM_GL_EXPORT AbstractQuery: public AbstractObject {
          *      with @def_gl{QUERY_OBJECT_EXT}
          * @requires_gles Debug output is not available in WebGL.
          */
-        AbstractQuery& setLabel(const std::string& label) {
-            return setLabelInternal({label.data(), label.size()});
-        }
-
-        /** @overload */
-        template<std::size_t size> AbstractQuery& setLabel(const char(&label)[size]) {
-            return setLabelInternal({label, size - 1});
-        }
+        AbstractQuery& setLabel(Containers::StringView label);
         #endif
 
         /**
@@ -183,10 +183,6 @@ class MAGNUM_GL_EXPORT AbstractQuery: public AbstractObject {
         GLenum _target;
 
     private:
-        #ifndef MAGNUM_TARGET_WEBGL
-        AbstractQuery& setLabelInternal(Containers::ArrayView<const char> label);
-        #endif
-
         void MAGNUM_GL_LOCAL createImplementationDefault();
         #ifndef MAGNUM_TARGET_GLES
         void MAGNUM_GL_LOCAL createImplementationDSA();

src/Magnum/GL/AbstractShaderProgram.cpp

@@ -27,6 +27,9 @@
 
 #include <Corrade/Containers/Array.h>
 #include <Corrade/Containers/StridedArrayView.h>
+#ifndef MAGNUM_TARGET_WEBGL
+#include <Corrade/Containers/String.h>
+#endif
 #include <Corrade/Containers/Reference.h>
 #include <Corrade/Utility/DebugStl.h>
 
@@ -315,15 +318,15 @@ AbstractShaderProgram& AbstractShaderProgram::operator=(AbstractShaderProgram&&
 }
 
 #ifndef MAGNUM_TARGET_WEBGL
-std::string AbstractShaderProgram::label() const {
+Containers::String AbstractShaderProgram::label() const {
     #ifndef MAGNUM_TARGET_GLES2
     return Context::current().state().debug.getLabelImplementation(GL_PROGRAM, _id);
     #else
     return Context::current().state().debug.getLabelImplementation(GL_PROGRAM_KHR, _id);
     #endif
 }
 
-AbstractShaderProgram& AbstractShaderProgram::setLabelInternal(const Containers::ArrayView<const char> label) {
+AbstractShaderProgram& AbstractShaderProgram::setLabel(const Containers::StringView label) {
     #ifndef MAGNUM_TARGET_GLES2
     Context::current().state().debug.labelImplementation(GL_PROGRAM, _id, label);
     #else

src/Magnum/GL/AbstractShaderProgram.h

@@ -41,6 +41,11 @@
 #include <vector>
 #endif
 
+#ifdef MAGNUM_BUILD_DEPRECATED
+/* For label() / setLabel(), which used to be a std::string */
+#include <Corrade/Containers/StringStl.h>
+#endif
+
 namespace Magnum { namespace GL {
 
 namespace Implementation { struct ShaderProgramState; }
@@ -726,7 +731,7 @@ class MAGNUM_GL_EXPORT AbstractShaderProgram: public AbstractObject {
          *      @def_gl{PROGRAM_OBJECT_EXT}
          * @requires_gles Debug output is not available in WebGL.
          */
-        std::string label() const;
+        Containers::String label() const;
 
         /**
          * @brief Set shader program label
@@ -741,14 +746,7 @@ class MAGNUM_GL_EXPORT AbstractShaderProgram: public AbstractObject {
          *      with @def_gl{PROGRAM_OBJECT_EXT}
          * @requires_gles Debug output is not available in WebGL.
          */
-        AbstractShaderProgram& setLabel(const std::string& label) {
-            return setLabelInternal({label.data(), label.size()});
-        }
-
-        /** @overload */
-        template<std::size_t size> AbstractShaderProgram& setLabel(const char (&label)[size]) {
-            return setLabelInternal({label, size - 1});
-        }
+        AbstractShaderProgram& setLabel(Containers::StringView label);
         #endif
 
         /**
@@ -1647,10 +1645,6 @@ class MAGNUM_GL_EXPORT AbstractShaderProgram: public AbstractObject {
         #endif
 
     private:
-        #ifndef MAGNUM_TARGET_WEBGL
-        AbstractShaderProgram& setLabelInternal(Containers::ArrayView<const char> label);
-        #endif
-
         void bindAttributeLocationInternal(UnsignedInt location, Containers::ArrayView<const char> name);
         #ifndef MAGNUM_TARGET_GLES
         void bindFragmentDataLocationIndexedInternal(UnsignedInt location, UnsignedInt index, Containers::ArrayView<const char> name);

src/Magnum/GL/AbstractTexture.cpp

@@ -27,6 +27,9 @@
 
 #include <tuple>
 #include <Corrade/Containers/Array.h>
+#ifndef MAGNUM_TARGET_WEBGL
+#include <Corrade/Containers/String.h>
+#endif
 
 #include "Magnum/Image.h"
 #include "Magnum/ImageView.h"
@@ -261,12 +264,12 @@ void AbstractTexture::createIfNotAlready() {
 }
 
 #ifndef MAGNUM_TARGET_WEBGL
-std::string AbstractTexture::label() {
+Containers::String AbstractTexture::label() {
     createIfNotAlready();
     return Context::current().state().debug.getLabelImplementation(GL_TEXTURE, _id);
 }
 
-AbstractTexture& AbstractTexture::setLabelInternal(const Containers::ArrayView<const char> label) {
+AbstractTexture& AbstractTexture::setLabel(const Containers::StringView label) {
     createIfNotAlready();
     Context::current().state().debug.labelImplementation(GL_TEXTURE, _id, label);
     return *this;