Fix BlockStateProvider item models not knowing about block models

Add tests for this case

src/generated_test/resources/.cache/cache

@@ -41,10 +41,12 @@ c4d268471ee793597917c966d1aaed29e438d366 assets/data_gen_test/models/block/oak_t
 2abb8b11c91441badd91b7c52f5f8ba3226c92de assets/data_gen_test/models/block/oak_trapdoor_open.json
 560d419e3d542cb0509bca078988308d387c15a9 assets/data_gen_test/models/block/oak_trapdoor_top.json
 556f0d997250661e0401fba13a4afd1bb0627dcc assets/data_gen_test/models/block/stone.json
+556f0d997250661e0401fba13a4afd1bb0627dcc assets/data_gen_test/models/block/test_block.json
 db2cd929128c8a6e8e0b02437f90ad8d24238206 assets/data_gen_test/models/block/torch.json
 81ce9ac0a7f4ed7a94d5496b918987a6f5a24988 assets/data_gen_test/models/block/wall_torch.json
 6b40df2a47c13cd00e295244b6cf74462938359d assets/data_gen_test/models/item/fishing_rod.json
 7fecdc30a209fca790df79b973c30b9e84415e0b assets/data_gen_test/models/item/fishing_rod_cast.json
+098d8b38409fff6cc14a4e56355bedb1fc5931d1 assets/data_gen_test/models/item/test_block.json
 b029993275f16569b0edf093362f55df6ea6f9be assets/data_gen_test/models/item/test_block_model.json
 726e1884e53151492ca05bd752c67031603570f6 assets/data_gen_test/models/item/test_generated_model.json
 1767c874758bd7c3235db446b6219e6e1edd25b4 assets/minecraft/blockstates/acacia_door.json

src/generated_test/resources/assets/data_gen_test/models/block/test_block.json

@@ -0,0 +1,6 @@
+{
+  "parent": "minecraft:block/cube_all",
+  "textures": {
+    "all": "minecraft:block/stone"
+  }
+}

src/generated_test/resources/assets/data_gen_test/models/item/test_block.json

@@ -0,0 +1,3 @@
+{
+  "parent": "data_gen_test:block/test_block"
+}

src/main/java/net/minecraftforge/client/model/generators/BlockStateProvider.java

@@ -95,7 +95,7 @@ public abstract class BlockStateProvider implements IDataProvider {
         this.blockModels = new BlockModelProvider(gen, modid, exFileHelper) {
             @Override protected void registerModels() {}
         };
-        this.itemModels = new ItemModelProvider(gen, modid, exFileHelper) {
+        this.itemModels = new ItemModelProvider(gen, modid, this.blockModels.existingFileHelper) {
             @Override protected void registerModels() {}
         };
     }

src/test/java/net/minecraftforge/debug/DataGeneratorTest.java

@@ -41,6 +41,7 @@ import com.google.common.collect.HashMultimap;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Multimap;
 import com.google.common.collect.ObjectArrays;
+import com.google.common.collect.Sets;
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
 import com.google.gson.JsonArray;
@@ -438,7 +439,7 @@ public class DataGeneratorTest
             ModelFile barrel = models().cubeBottomTop("barrel", mcLoc("block/barrel_side"), mcLoc("block/barrel_bottom"), mcLoc("block/barrel_top"));
             ModelFile barrelOpen = models().cubeBottomTop("barrel_open", mcLoc("block/barrel_side"), mcLoc("block/barrel_bottom"), mcLoc("block/barrel_top_open"));
             directionalBlock(Blocks.BARREL, state -> state.get(BarrelBlock.PROPERTY_OPEN) ? barrelOpen : barrel); // Testing custom state interpreter
-
+            
             logBlock((RotatedPillarBlock) Blocks.ACACIA_LOG);
 
             stairsBlock((StairsBlock) Blocks.ACACIA_STAIRS, "acacia", mcLoc("block/acacia_planks"));
@@ -457,6 +458,9 @@ public class DataGeneratorTest
 
             simpleBlock(Blocks.TORCH, models().torch("torch", mcLoc("block/torch")));
             horizontalBlock(Blocks.WALL_TORCH, models().torchWall("wall_torch", mcLoc("block/torch")), 90);
+
+            models().cubeAll("test_block", mcLoc("block/stone"));
+            itemModels().withExistingParent("test_block", modLoc("block/test_block"));
         }
 
         // Testing the outputs
@@ -465,6 +469,7 @@ public class DataGeneratorTest
         // Vanilla doesn't generate these models yet, so they have minor discrepancies that are hard to test
         // This list should probably be cleared and investigated after each major version update
         private static final Set<ResourceLocation> IGNORED_MODELS = ImmutableSet.of(new ResourceLocation(MODID, "block/cube"));
+        private static final Set<ResourceLocation> CUSTOM_MODELS = ImmutableSet.of(new ResourceLocation(MODID, "block/test_block"));
 
         private List<String> errors = new ArrayList<>();
 
@@ -472,7 +477,7 @@ public class DataGeneratorTest
         public void act(DirectoryCache cache) throws IOException
         {
             super.act(cache);
-            this.errors.addAll(testModelResults(models().generatedModels, models().existingFileHelper, IGNORED_MODELS));
+            this.errors.addAll(testModelResults(models().generatedModels, models().existingFileHelper, Sets.union(IGNORED_MODELS, CUSTOM_MODELS)));
             this.registeredBlocks.forEach((block, state) -> {
                 if (IGNORED_BLOCKS.contains(block)) return;
                 JsonObject generated = state.toJson();