Fix pruning empty declarations from loop headers

src/compiler/translator/PruneEmptyDeclarations.cpp

@@ -63,9 +63,17 @@ bool PruneEmptyDeclarationsTraverser::visitAggregate(Visit, TIntermAggregate *no
                     // float;
                     TIntermSequence emptyReplacement;
                     TIntermBlock *parentAsBlock = getParentNode()->getAsBlock();
-                    ASSERT(parentAsBlock != nullptr);
-                    mMultiReplacements.push_back(
-                        NodeReplaceWithMultipleEntry(parentAsBlock, node, emptyReplacement));
+                    // The declaration may be inside a block or in a loop init expression.
+                    ASSERT(parentAsBlock != nullptr || getParentNode()->getAsLoopNode() != nullptr);
+                    if (parentAsBlock)
+                    {
+                        mMultiReplacements.push_back(
+                            NodeReplaceWithMultipleEntry(parentAsBlock, node, emptyReplacement));
+                    }
+                    else
+                    {
+                        queueReplacement(node, nullptr, OriginalNode::IS_DROPPED);
+                    }
                 }
                 else if (sym->getType().getQualifier() != EvqGlobal &&
                          sym->getType().getQualifier() != EvqTemporary)

src/tests/compiler_tests/MalformedShader_test.cpp

@@ -2563,3 +2563,24 @@ TEST_F(MalformedShaderTest, DeferGlobalVariableInitWithEmptyMain)
         FAIL() << "Shader compilation failed, expecting success " << mInfoLog;
     }
 }
+
+// Test that pruning empty declarations from loop init expression works.
+TEST_F(MalformedShaderTest, EmptyDeclarationAsLoopInit)
+{
+    const std::string &shaderString =
+        "#version 300 es\n"
+        "precision mediump float;\n"
+        "out vec4 my_FragColor;\n"
+        "void main()\n"
+        "{\n"
+        "    int i = 0;\n"
+        "    for (int; i < 3; i++)\n"
+        "    {\n"
+        "        my_FragColor = vec4(i);\n"
+        "    }\n"
+        "}\n";
+    if (!compile(shaderString))
+    {
+        FAIL() << "Shader compilation failed, expecting success " << mInfoLog;
+    }
+}