GL: advertise the "intel-windows-chatty-shader-compiler" workaround.

This was done silently until now and I think such platform-specific code
should be always exposed as a disableable workaround. Moreover, I need a
similar thing for ANGLE, so this comes handy.

doc/changelog.dox

@@ -175,6 +175,10 @@ See also:
 -   Added @ref GL::Framebuffer::Status::IncompleteDimensions for ES2. This enum
     isn't available on ES3 or desktop GL, but NVidia drivers are known to emit
     it, which is why it got added.
+-   Intel/Windows-specific code for silencing useless shader compiler output is
+    now advertised as a @cpp "intel-windows-chatty-shader-compiler" @ce
+    workaround, instead of being done silently. See @ref opengl-workarounds for
+    more information.
 
 @subsubsection changelog-latest-changes-math Math library
 

src/Magnum/GL/AbstractShaderProgram.cpp

@@ -46,11 +46,6 @@
 
 namespace Magnum { namespace GL {
 
-namespace Implementation {
-    /* Defined in Implementation/driverSpecific.cpp */
-    bool isProgramLinkLogEmpty(const std::string& result);
-}
-
 Int AbstractShaderProgram::maxVertexAttributes() {
     GLint& value = Context::current().state().shaderProgram->maxVertexAttributes;
 
@@ -508,12 +503,16 @@ bool AbstractShaderProgram::link(std::initializer_list<Containers::Reference<Abs
         glGetProgramiv(shader._id, GL_INFO_LOG_LENGTH, &logLength);
 
         /* Error or warning message. The string is returned null-terminated,
-           scrap the \0 at the end afterwards */
+           strip the \0 at the end afterwards. */
         std::string message(logLength, '\n');
         if(message.size() > 1)
             glGetProgramInfoLog(shader._id, message.size(), nullptr, &message[0]);
         message.resize(Math::max(logLength, 1)-1);
 
+        /* Some drivers are chatty and can't keep shut when there's nothing to
+           be said, handle that as well. */
+        Context::current().state().shaderProgram->cleanLogImplementation(message);
+
         /* Show error log */
         if(!success) {
             Error out{Debug::Flag::NoNewlineAtTheEnd};
@@ -522,7 +521,7 @@ bool AbstractShaderProgram::link(std::initializer_list<Containers::Reference<Abs
             out << "failed with the following message:" << Debug::newline << message;
 
         /* Or just warnings, if any */
-        } else if(!message.empty() && !Implementation::isProgramLinkLogEmpty(message)) {
+        } else if(!message.empty()) {
             Warning out{Debug::Flag::NoNewlineAtTheEnd};
             out << "GL::AbstractShaderProgram::link(): linking";
             if(shaders.size() != 1) out << "of shader" << i;
@@ -537,6 +536,14 @@ bool AbstractShaderProgram::link(std::initializer_list<Containers::Reference<Abs
     return allSuccess;
 }
 
+void AbstractShaderProgram::cleanLogImplementationNoOp(std::string&) {}
+
+#if defined(CORRADE_TARGET_WINDOWS) && !defined(MAGNUM_TARGET_GLES)
+void AbstractShaderProgram::cleanLogImplementationIntelWindows(std::string& message) {
+    if(message == "No errors.\n") message = {};
+}
+#endif
+
 Int AbstractShaderProgram::uniformLocationInternal(const Containers::ArrayView<const char> name) {
     const GLint location = glGetUniformLocation(_id, name);
     if(location == -1)

src/Magnum/GL/AbstractShaderProgram.h

@@ -1347,6 +1347,11 @@ class MAGNUM_GL_EXPORT AbstractShaderProgram: public AbstractObject {
         #endif
         #endif
 
+        static MAGNUM_GL_LOCAL void cleanLogImplementationNoOp(std::string& message);
+        #if defined(CORRADE_TARGET_WINDOWS) && !defined(MAGNUM_TARGET_GLES)
+        static MAGNUM_GL_LOCAL void cleanLogImplementationIntelWindows(std::string& message);
+        #endif
+
         void use();
 
         /*

src/Magnum/GL/Implementation/ShaderProgramState.cpp

@@ -60,6 +60,15 @@ ShaderProgramState::ShaderProgramState(Context& context, std::vector<std::string
     }
     #endif
 
+    #if defined(CORRADE_TARGET_WINDOWS) && !defined(MAGNUM_TARGET_GLES)
+    if((context.detectedDriver() & Context::DetectedDriver::IntelWindows) && !context.isDriverWorkaroundDisabled("intel-windows-chatty-shader-compiler")) {
+        cleanLogImplementation = &AbstractShaderProgram::cleanLogImplementationIntelWindows;
+    } else
+    #endif
+    {
+        cleanLogImplementation = &AbstractShaderProgram::cleanLogImplementationNoOp;
+    }
+
     #if !defined(MAGNUM_TARGET_GLES2) && !defined(MAGNUM_TARGET_WEBGL)
     #ifndef MAGNUM_TARGET_GLES
     if(context.isExtensionSupported<Extensions::ARB::separate_shader_objects>())

src/Magnum/GL/Implementation/ShaderProgramState.h

@@ -46,6 +46,7 @@ struct ShaderProgramState {
     #ifndef MAGNUM_TARGET_GLES2
     void(AbstractShaderProgram::*transformFeedbackVaryingsImplementation)(Containers::ArrayView<const std::string>, AbstractShaderProgram::TransformFeedbackBufferMode);
     #endif
+    void(*cleanLogImplementation)(std::string&);
 
     void(AbstractShaderProgram::*uniform1fvImplementation)(GLint, GLsizei, const GLfloat*);
     void(AbstractShaderProgram::*uniform2fvImplementation)(GLint, GLsizei, const Math::Vector<2, GLfloat>*);

src/Magnum/GL/Implementation/ShaderState.cpp

@@ -25,11 +25,10 @@
 
 #include "ShaderState.h"
 
-#include "Magnum/GL/Shader.h"
-
-#if defined(CORRADE_TARGET_EMSCRIPTEN) && defined(__EMSCRIPTEN_PTHREADS__)
+/* Needed only for Emscripten+pthread- / Windows+Intel-specific workarounds,
+   but I won't bother crafting the preprocessor logic for this. */
 #include "Magnum/GL/Context.h"
-#endif
+#include "Magnum/GL/Shader.h"
 
 namespace Magnum { namespace GL { namespace Implementation {
 
@@ -56,9 +55,18 @@ ShaderState::ShaderState(Context& context, std::vector<std::string>&):
         addSourceImplementation = &Shader::addSourceImplementationDefault;
     }
 
-    #if !defined(CORRADE_TARGET_EMSCRIPTEN) || !defined(__EMSCRIPTEN_PTHREADS__)
-    static_cast<void>(context);
+    #if defined(CORRADE_TARGET_WINDOWS) && !defined(MAGNUM_TARGET_GLES)
+    if((context.detectedDriver() & Context::DetectedDriver::IntelWindows) && !context.isDriverWorkaroundDisabled("intel-windows-chatty-shader-compiler")) {
+        cleanLogImplementation = &Shader::cleanLogImplementationIntelWindows;
+    } else
     #endif
+    {
+        cleanLogImplementation = &Shader::cleanLogImplementationNoOp;
+    }
+
+    /* Needed only if neither of these ifdefs above hits, but I won't bother
+       crafting the preprocessor logic for this. */
+    static_cast<void>(context);
 }
 
 }}}

src/Magnum/GL/Implementation/ShaderState.h

@@ -52,6 +52,7 @@ struct ShaderState {
     };
 
     void(Shader::*addSourceImplementation)(std::string);
+    void(*cleanLogImplementation)(std::string&);
 
     GLint maxVertexOutputComponents,
         maxFragmentInputComponents;

src/Magnum/GL/Implementation/driverSpecific.cpp

@@ -336,6 +336,10 @@ const char* KnownWorkarounds[]{
    MeshGLTest::addVertexBufferIntWithShort(). */
 "intel-windows-broken-dsa-integer-vertex-attributes",
 
+/* Shader compiler on Intel Windows drivers insists on telling me "No errors."
+   when it should just stay silent. */
+"intel-windows-chatty-shader-compiler",
+
 /* When using more than just a vertex and fragment shader (geometry shader,
    e.g.), ARB_explicit_uniform_location on Intel silently uses wrong
    locations, blowing up with either a non-descript
@@ -382,38 +386,6 @@ const char* KnownWorkarounds[]{
 
 }
 
-namespace Implementation {
-
-/* Used in Shader.cpp (duh) */
-bool isShaderCompilationLogEmpty(const std::string&);
-bool isShaderCompilationLogEmpty(const std::string& result) {
-    #if defined(CORRADE_TARGET_WINDOWS) && !defined(MAGNUM_TARGET_GLES)
-    /* Intel Windows drivers are too chatty */
-    if((Context::current().detectedDriver() & Context::DetectedDriver::IntelWindows) && result == "No errors.\n")
-        return true;
-    #else
-    static_cast<void>(result);
-    #endif
-
-    return false;
-}
-
-/* Used in AbstractShaderProgram.cpp (duh) */
-bool isProgramLinkLogEmpty(const std::string&);
-bool isProgramLinkLogEmpty(const std::string& result) {
-    #if defined(CORRADE_TARGET_WINDOWS) && !defined(MAGNUM_TARGET_GLES)
-    /* Intel Windows drivers are too chatty */
-    if((Context::current().detectedDriver() & Context::DetectedDriver::IntelWindows) && result == "No errors.\n")
-        return true;
-    #else
-    static_cast<void>(result);
-    #endif
-
-    return false;
-}
-
-}
-
 auto Context::detectedDriver() -> DetectedDrivers {
     if(_detectedDrivers) return *_detectedDrivers;
 

src/Magnum/GL/Shader.cpp

@@ -48,11 +48,6 @@ typedef char GLchar;
 
 namespace Magnum { namespace GL {
 
-namespace Implementation {
-    /* defined in Implementation/driverSpecific.cpp */
-    bool isShaderCompilationLogEmpty(const std::string& result);
-}
-
 namespace {
 
 std::string shaderName(const Shader::Type type) {
@@ -786,12 +781,16 @@ bool Shader::compile(std::initializer_list<Containers::Reference<Shader>> shader
         glGetShaderiv(shader._id, GL_INFO_LOG_LENGTH, &logLength);
 
         /* Error or warning message. The string is returned null-terminated,
-           scrap the \0 at the end afterwards */
+           strip the \0 at the end afterwards. */
         std::string message(logLength, '\0');
         if(message.size() > 1)
             glGetShaderInfoLog(shader._id, message.size(), nullptr, &message[0]);
         message.resize(Math::max(logLength, 1)-1);
 
+        /* Some drivers are chatty and can't keep shut when there's nothing to
+           be said, handle that as well. */
+        Context::current().state().shader->cleanLogImplementation(message);
+
         /* Show error log */
         if(!success) {
             Error out{Debug::Flag::NoNewlineAtTheEnd};
@@ -800,7 +799,7 @@ bool Shader::compile(std::initializer_list<Containers::Reference<Shader>> shader
             out << "failed with the following message:" << Debug::newline << message;
 
         /* Or just warnings, if any */
-        } else if(!message.empty() && !Implementation::isShaderCompilationLogEmpty(message)) {
+        } else if(!message.empty()) {
             Warning out{Debug::Flag::NoNewlineAtTheEnd};
             out << "GL::Shader::compile(): compilation of" << shaderName(shader._type) << "shader";
             if(shaders.size() != 1) out << i;
@@ -815,6 +814,14 @@ bool Shader::compile(std::initializer_list<Containers::Reference<Shader>> shader
     return allSuccess;
 }
 
+void Shader::cleanLogImplementationNoOp(std::string&) {}
+
+#if defined(CORRADE_TARGET_WINDOWS) && !defined(MAGNUM_TARGET_GLES)
+void Shader::cleanLogImplementationIntelWindows(std::string& message) {
+    if(message == "No errors.\n") message = {};
+}
+#endif
+
 #ifndef DOXYGEN_GENERATING_OUTPUT
 Debug& operator<<(Debug& debug, const Shader::Type value) {
     debug << "GL::Shader::Type" << Debug::nospace;

src/Magnum/GL/Shader.h

@@ -652,6 +652,11 @@ class MAGNUM_GL_EXPORT Shader: public AbstractObject {
         void MAGNUM_GL_LOCAL addSourceImplementationEmscriptenPthread(std::string source);
         #endif
 
+        static MAGNUM_GL_LOCAL void cleanLogImplementationNoOp(std::string& message);
+        #if defined(CORRADE_TARGET_WINDOWS) && !defined(MAGNUM_TARGET_GLES)
+        static MAGNUM_GL_LOCAL void cleanLogImplementationIntelWindows(std::string& message);
+        #endif
+
         Type _type;
         GLuint _id;