Make sure the default framebuffer has enough draw buffer states.

src/libANGLE/ContextState.cpp

@@ -133,13 +133,6 @@ ValidationContext::ValidationContext(const ValidationContext *shareContext,
 
 bool ValidationContext::getQueryParameterInfo(GLenum pname, GLenum *type, unsigned int *numParams)
 {
-    if (pname >= GL_DRAW_BUFFER0_EXT && pname <= GL_DRAW_BUFFER15_EXT)
-    {
-        *type      = GL_INT;
-        *numParams = 1;
-        return true;
-    }
-
     // Please note: the query type returned for DEPTH_CLEAR_VALUE in this implementation
     // is FLOAT rather than INT, as would be suggested by the GL ES 2.0 spec. This is due
     // to the fact that it is stored internally as a float, and so would require conversion
@@ -495,6 +488,17 @@ bool ValidationContext::getQueryParameterInfo(GLenum pname, GLenum *type, unsign
         }
     }
 
+    if (pname >= GL_DRAW_BUFFER0_EXT && pname <= GL_DRAW_BUFFER15_EXT)
+    {
+        if ((getClientVersion() < Version(3, 0)) && !getExtensions().drawBuffers)
+        {
+            return false;
+        }
+        *type      = GL_INT;
+        *numParams = 1;
+        return true;
+    }
+
     if (getClientVersion() < Version(3, 0))
     {
         return false;

src/libANGLE/Framebuffer.cpp

@@ -45,7 +45,7 @@ void BindResourceChannel(ChannelBinding *binding, FramebufferAttachmentObject *r
 FramebufferState::FramebufferState()
     : mLabel(),
       mColorAttachments(1),
-      mDrawBufferStates(1, GL_BACK),
+      mDrawBufferStates(IMPLEMENTATION_MAX_DRAW_BUFFERS, GL_NONE),
       mReadBufferState(GL_BACK),
       mDefaultWidth(0),
       mDefaultHeight(0),
@@ -53,6 +53,8 @@ FramebufferState::FramebufferState()
       mDefaultFixedSampleLocations(GL_FALSE),
       mWebGLDepthStencilConsistent(true)
 {
+    ASSERT(mDrawBufferStates.size() > 0);
+    mDrawBufferStates[0] = GL_BACK;
     mEnabledDrawBuffers.set(0);
 }
 

src/libANGLE/renderer/d3d/d3d11/Clear11.cpp

@@ -200,7 +200,7 @@ gl::Error Clear11::clearFramebuffer(const ClearParameters &clearParams,
     const auto *depthAttachment   = fboData.getDepthAttachment();
     const auto *stencilAttachment = fboData.getStencilAttachment();
 
-    ASSERT(colorAttachments.size() == drawBufferStates.size());
+    ASSERT(colorAttachments.size() <= drawBufferStates.size());
 
     // Iterate over the color buffers which require clearing and determine if they can be
     // cleared with ID3D11DeviceContext::ClearRenderTargetView or ID3D11DeviceContext1::ClearView.