Make gl.useProgram(null) do the right thing

components/canvas/webgl_thread.rs

@@ -826,8 +826,6 @@ impl WebGLImpl {
                 ctx.gl().uniform_matrix_3fv(uniform_id, transpose, v),
             WebGLCommand::UniformMatrix4fv(uniform_id, transpose,  ref v) =>
                 ctx.gl().uniform_matrix_4fv(uniform_id, transpose, v),
-            WebGLCommand::UseProgram(program_id) =>
-                ctx.gl().use_program(program_id.get()),
             WebGLCommand::ValidateProgram(program_id) =>
                 ctx.gl().validate_program(program_id.get()),
             WebGLCommand::VertexAttrib(attrib_id, x, y, z, w) =>
@@ -965,6 +963,9 @@ impl WebGLImpl {
             WebGLCommand::LinkProgram(program_id, ref sender) => {
                 return sender.send(Self::link_program(ctx.gl(), program_id)).unwrap();
             }
+            WebGLCommand::UseProgram(program_id) => {
+                ctx.gl().use_program(program_id.map_or(0, |p| p.get()))
+            }
         }
 
         // TODO: update test expectations in order to enable debug assertions

components/canvas_traits/webgl.rs

@@ -249,7 +249,7 @@ pub enum WebGLCommand {
     UniformMatrix2fv(i32, bool, Vec<f32>),
     UniformMatrix3fv(i32, bool, Vec<f32>),
     UniformMatrix4fv(i32, bool, Vec<f32>),
-    UseProgram(WebGLProgramId),
+    UseProgram(Option<WebGLProgramId>),
     ValidateProgram(WebGLProgramId),
     VertexAttrib(u32, f32, f32, f32, f32),
     VertexAttribPointer(u32, i32, u32, bool, i32, u32),

components/script/dom/webglprogram.rs

@@ -130,19 +130,6 @@ impl WebGLProgram {
         Ref::map(self.active_attribs.borrow(), |attribs| &**attribs)
     }
 
-    /// glUseProgram
-    pub fn use_program(&self) -> WebGLResult<()> {
-        if self.is_deleted() {
-            return Err(WebGLError::InvalidOperation);
-        }
-        if !self.linked.get() {
-            return Err(WebGLError::InvalidOperation);
-        }
-
-        self.renderer.send(WebGLCommand::UseProgram(self.id)).unwrap();
-        Ok(())
-    }
-
     /// glValidateProgram
     pub fn validate(&self) -> WebGLResult<()> {
         if self.is_deleted() {

components/script/dom/webglrenderingcontext.rs

@@ -2314,7 +2314,7 @@ impl WebGLRenderingContextMethods for WebGLRenderingContext {
 
     // https://www.khronos.org/registry/webgl/specs/latest/1.0/#5.14.10
     fn GetActiveAttrib(&self, program: &WebGLProgram, index: u32) -> Option<DomRoot<WebGLActiveInfo>> {
-        handle_potential_webgl_error!(self, program.get_active_attrib(index), None)
+        handle_potential_webgl_error!(self, program.get_active_attrib(index).map(Some), None)
     }
 
     // https://www.khronos.org/registry/webgl/specs/latest/1.0/#5.14.10
@@ -3242,11 +3242,12 @@ impl WebGLRenderingContextMethods for WebGLRenderingContext {
     // https://www.khronos.org/registry/webgl/specs/latest/1.0/#5.14.9
     fn UseProgram(&self, program: Option<&WebGLProgram>) {
         if let Some(program) = program {
-            match program.use_program() {
+            if program.is_deleted() || !program.is_linked() {
-                Ok(()) => self.current_program.set(Some(program)),
+                return self.webgl_error(InvalidOperation);
-                Err(e) => self.webgl_error(e),
             }
         }
+        self.send_command(WebGLCommand::UseProgram(program.map(|p| p.id())));
+        self.current_program.set(program);
     }
 
     // https://www.khronos.org/registry/webgl/specs/latest/1.0/#5.14.9

tests/wpt/mozilla/meta/webgl/conformance-1.0.3/conformance/programs/program-test.html.ini

@@ -1,7 +1,4 @@
 [program-test.html]
-  [WebGL test #53: getError expected: INVALID_OPERATION. Was NO_ERROR : drawing with a null program should generate INVALID_OPERATION]
-    expected: FAIL
-
   [WebGL test #64: getError expected: NO_ERROR. Was INVALID_OPERATION : delete the current program shouldn't change the current rendering state]
     expected: FAIL