Fix ESSL3 indexing corner cases

src/compiler/translator/ParseContext.cpp

@@ -2698,6 +2698,27 @@ TIntermTyped *TParseContext::addIndexExpression(TIntermTyped *baseExpression,
 
     TIntermConstantUnion *indexConstantUnion = indexExpression->getAsConstantUnion();
 
+    // TODO(oetuaho@nvidia.com): Get rid of indexConstantUnion == nullptr below once ANGLE is able
+    // to constant fold all constant expressions. Right now we don't allow indexing interface blocks
+    // or fragment outputs with expressions that ANGLE is not able to constant fold, even if the
+    // index is a constant expression.
+    if (indexExpression->getQualifier() != EvqConst || indexConstantUnion == nullptr)
+    {
+        if (baseExpression->isInterfaceBlock())
+        {
+            error(
+                location, "", "[",
+                "array indexes for interface blocks arrays must be constant integral expressions");
+            recover();
+        }
+        else if (baseExpression->getQualifier() == EvqFragmentOut)
+        {
+            error(location, "", "[",
+                  "array indexes for fragment outputs must be constant integral expressions");
+            recover();
+        }
+    }
+
     if (indexConstantUnion)
     {
         // If the index is not qualified as constant, the behavior in the spec is undefined. This
@@ -2790,20 +2811,6 @@ TIntermTyped *TParseContext::addIndexExpression(TIntermTyped *baseExpression,
     }
     else
     {
-        if (baseExpression->isInterfaceBlock())
-        {
-            error(
-                location, "", "[",
-                "array indexes for interface blocks arrays must be constant integral expressions");
-            recover();
-        }
-        else if (baseExpression->getQualifier() == EvqFragmentOut)
-        {
-            error(location, "", "[",
-                  "array indexes for fragment outputs must be constant integral expressions");
-            recover();
-        }
-
         indexedExpression =
             intermediate.addIndex(EOpIndexIndirect, baseExpression, indexExpression, location);
     }

src/tests/compiler_tests/MalformedShader_test.cpp

@@ -1158,3 +1158,46 @@ TEST_F(MalformedShaderTest, EmptyArrayConstructor)
         FAIL() << "Shader compilation succeeded, expecting failure " << mInfoLog;
     }
 }
+
+// Test that indexing fragment outputs with a non-constant expression is forbidden, even if ANGLE
+// is able to constant fold the index expression. ESSL 3.00 section 4.3.6.
+TEST_F(MalformedShaderTest, DynamicallyIndexedFragmentOutput)
+{
+    const std::string &shaderString =
+        "#version 300 es"
+        "precision mediump float;\n"
+        "uniform int a;\n"
+        "out vec4[2] my_FragData;\n"
+        "void main()\n"
+        "{\n"
+        "    my_FragData[true ? 0 : a] = vec4(0.0);\n"
+        "}\n";
+    if (compile(shaderString))
+    {
+        FAIL() << "Shader compilation succeeded, expecting failure " << mInfoLog;
+    }
+}
+
+// Test that indexing an interface block array with a non-constant expression is forbidden, even if
+// ANGLE is able to constant fold the index expression. ESSL 3.00 section 4.3.7.
+TEST_F(MalformedShaderTest, DynamicallyIndexedInterfaceBlock)
+{
+    const std::string &shaderString =
+        "#version 300 es"
+        "precision mediump float;\n"
+        "uniform int a;\n"
+        "uniform B\n"
+        "{\n"
+        "    vec4 f;\n"
+        "}\n"
+        "blocks[2];\n"
+        "out vec4 my_FragColor;\n"
+        "void main()\n"
+        "{\n"
+        "    my_FragColor = blocks[true ? 0 : a].f;\n"
+        "}\n";
+    if (compile(shaderString))
+    {
+        FAIL() << "Shader compilation succeeded, expecting failure " << mInfoLog;
+    }
+}