Add sampler array index validation for ESSL 3.00 onwards

src/compiler/translator/ParseContext.cpp

@@ -4024,6 +4024,29 @@ TIntermTyped *TParseContext::addIndexExpression(TIntermTyped *baseExpression,
         {
             error(location, "array index for gl_FragData must be constant zero", "[");
         }
+        else if (baseExpression->isArray())
+        {
+            TType elementType;
+            switch (mShaderVersion)
+            {
+                case 100:
+                    break;
+                case 300:
+                case 310:
+                    elementType = baseExpression->getType();
+                    elementType.toArrayElementType();
+                    if (elementType.isSampler())
+                    {
+                        error(location,
+                              "array index for samplers must be constant integral expressions",
+                              "[");
+                    }
+                    break;
+                default:
+                    UNREACHABLE();
+                    break;
+            }
+        }
     }
 
     if (indexConstantUnion)

src/tests/compiler_tests/ShaderValidation_test.cpp

@@ -1305,6 +1305,26 @@ TEST_F(FragmentShaderValidationTest, DynamicallyIndexedInterfaceBlock)
     }
 }
 
+// Test that indexing a sampler array with a non-constant expression is forbidden, even if ANGLE is
+// able to constant fold the index expression. ESSL 3.00 section 4.1.7.1.
+TEST_F(FragmentShaderValidationTest, DynamicallyIndexedSampler)
+{
+    const std::string &shaderString =
+        "#version 300 es\n"
+        "precision mediump float;\n"
+        "uniform int a;\n"
+        "uniform sampler2D s[2];\n"
+        "out vec4 my_FragColor;\n"
+        "void main()\n"
+        "{\n"
+        "    my_FragColor = texture(s[true ? 0 : a], vec2(0));\n"
+        "}\n";
+    if (compile(shaderString))
+    {
+        FAIL() << "Shader compilation succeeded, expecting failure:\n" << mInfoLog;
+    }
+}
+
 // Test that a shader that uses a struct definition in place of a struct constructor does not
 // compile. See GLSL ES 1.00 section 5.4.3.
 TEST_F(FragmentShaderValidationTest, StructConstructorWithStructDefinition)