Fix assert when linking nonexistent transform feedback varying

src/libANGLE/Program.cpp

@@ -751,11 +751,6 @@ Error Program::link(const gl::Context *context)
 
         const auto &mergedVaryings = getMergedVaryings(context);
 
-        if (!linkValidateTransformFeedback(context, mInfoLog, mergedVaryings, caps))
-        {
-            return NoError();
-        }
-
         mState.mNumViews = vertexShader->getNumViews(context);
 
         linkOutputVariables(context);
@@ -774,6 +769,11 @@ Error Program::link(const gl::Context *context)
             return NoError();
         }
 
+        if (!linkValidateTransformFeedback(context, mInfoLog, mergedVaryings, caps))
+        {
+            return NoError();
+        }
+
         ANGLE_TRY_RESULT(mProgram->link(context, varyingPacking, mInfoLog), mLinked);
         if (!mLinked)
         {
@@ -2466,7 +2466,8 @@ bool Program::linkValidateTransformFeedback(const gl::Context *context,
             infoLog << "Capture of array elements is undefined and not supported.";
             return false;
         }
-        // All transform feedback varyings are expected to exist since packVaryings checks for them.
+        // All transform feedback varyings are expected to exist since packUserVaryings checks for
+        // them.
         ASSERT(found);
     }
 

src/tests/gl_tests/TransformFeedbackTest.cpp

@@ -1207,6 +1207,37 @@ TEST_P(TransformFeedbackTestES31, DifferentArrayElementVaryings)
     ASSERT_GL_NO_ERROR();
 }
 
+// Test that nonexistent transform feedback varyings don't assert when linking.
+TEST_P(TransformFeedbackTest, NonExistentTransformFeedbackVarying)
+{
+    const std::string &vertexShaderSource =
+        "#version 300 es\n"
+        "in vec4 a_position;\n"
+        "out vec4 v_position;\n"
+        "void main()\n"
+        "{\n"
+        "    v_position = a_position;\n"
+        "    gl_Position = a_position;\n"
+        "}\n";
+
+    const std::string &fragmentShaderSource =
+        "#version 300 es\n"
+        "precision mediump float;\n"
+        "in vec4 v_position;\n"
+        "out vec4 fragColor;\n"
+        "void main()\n"
+        "{\n"
+        "    fragColor = v_position;\n"
+        "}\n";
+
+    std::vector<std::string> tfVaryings;
+    tfVaryings.push_back("bogus");
+
+    mProgram = CompileProgramWithTransformFeedback(vertexShaderSource, fragmentShaderSource,
+                                                   tfVaryings, GL_INTERLEAVED_ATTRIBS);
+    ASSERT_EQ(0u, mProgram);
+}
+
 // Use this to select which configurations (e.g. which renderer, which GLES major version) these
 // tests should be run against.
 ANGLE_INSTANTIATE_TEST(TransformFeedbackTest, ES3_D3D11(), ES3_OPENGL(), ES3_OPENGLES());