DNA: support renaming structs that use the old renaming hack

source/blender/makesdna/intern/dna_genfile.c

@@ -384,34 +384,8 @@ static bool init_structDNA(
 
 		cp = (char *)data;
 		for (int nr = 0; nr < sdna->nr_types; nr++) {
-			sdna->types[nr] = cp;
-
-			/* ------------------------------------------------------------- */
-			/* WARNING!
-			 *
-			 * The renaming here isn't complete, references to the old struct names
-			 * are still included in DNA, now fixing these struct names properly
-			 * breaks forward compatibility. Leave these as-is, but don't add to them!
-			 * See D4342#98780 */
-
-			/* this is a patch, to change struct names without a conflict with SDNA */
-			/* be careful to use it, in this case for a system-struct (opengl/X) */
-
-			/* struct Screen was already used by X,
-			 * 'bScreen' replaces the old IrisGL 'Screen' struct */
-			if (strcmp("bScreen", cp) == 0) {
-				sdna->types[nr] = cp + 1;
-			}
-			/* Groups renamed to collections in 2.8 */
-			else if (strcmp("Collection", cp) == 0) {
-				sdna->types[nr] = "Group";
-			}
-			else if (strcmp("CollectionObject", cp) == 0) {
-				sdna->types[nr] = "GroupObject";
-			}
-			/* END WARNING */
-			/* ------------------------------------------------------------- */
-
+			/* WARNING! See: DNA_struct_rename_legacy_hack_static_from_alias docs. */
+			sdna->types[nr] = DNA_struct_rename_legacy_hack_static_from_alias(cp);
 			while (*cp) cp++;
 			cp++;
 		}
@@ -1530,6 +1504,9 @@ static const char *dna_sdna_alias_alias_from_static_elem_full(
 
 void DNA_sdna_alias_data_ensure(SDNA *sdna)
 {
+	/* We may want this to be optional later. */
+	const bool use_legacy_hack = true;
+
 	if (sdna->mem_arena == NULL) {
 		sdna->mem_arena = BLI_memarena_new(BLI_MEMARENA_STD_BUFSIZE, __func__);
 	}
@@ -1546,9 +1523,14 @@ void DNA_sdna_alias_data_ensure(SDNA *sdna)
 	if (sdna->alias.types == NULL) {
 		sdna->alias.types = MEM_mallocN(sizeof(*sdna->alias.types) * sdna->nr_types, __func__);
 		for (int type_nr = 0; type_nr < sdna->nr_types; type_nr++) {
-			const char *str = sdna->types[type_nr];
+			const char *struct_name_static = sdna->types[type_nr];
+
+			if (use_legacy_hack) {
+				struct_name_static = DNA_struct_rename_legacy_hack_alias_from_static(struct_name_static);
+			}
+
 			sdna->alias.types[type_nr] = BLI_ghash_lookup_default(
-			        struct_map_alias_from_static, str, (void *)str);
+			        struct_map_alias_from_static, struct_name_static, (void *)struct_name_static);
 		}
 	}
 
@@ -1558,6 +1540,11 @@ void DNA_sdna_alias_data_ensure(SDNA *sdna)
 		for (int struct_nr = 0; struct_nr < sdna->nr_structs; struct_nr++) {
 			const short *sp = sdna->structs[struct_nr];
 			const char *struct_name_static = sdna->types[sp[0]];
+
+			if (use_legacy_hack) {
+				struct_name_static = DNA_struct_rename_legacy_hack_alias_from_static(struct_name_static);
+			}
+
 			const int dna_struct_names_len = sp[1];
 			sp += 2;
 			for (int a = 0; a < dna_struct_names_len; a++, sp += 2) {

source/blender/makesdna/intern/dna_utils.c

@@ -281,3 +281,52 @@ void DNA_alias_maps(
 #undef DNA_MAKESDNA
 
 /** \} */
+
+/* -------------------------------------------------------------------- */
+/** \name Struct Name Legacy Hack
+ * \{ */
+
+/**
+ * DNA Compatibility Hack
+ * ======================
+ *
+ * Only keep this for compatibility: **NEVER ADD NEW STRINGS HERE**.
+ *
+ * The renaming here isn't complete, references to the old struct names
+ * are still included in DNA, now fixing these struct names properly
+ * breaks forward compatibility. Leave these as-is, but don't add to them!
+ * See D4342#98780
+ */
+const char *DNA_struct_rename_legacy_hack_static_from_alias(const char *name)
+{
+	/* 'bScreen' replaces the old IrisGL 'Screen' struct */
+	if (STREQ("bScreen", name)) {
+		return "Screen";
+	}
+	/* Groups renamed to collections in 2.8 */
+	if (STREQ("Collection", name)) {
+		return "Group";
+	}
+	if (STREQ("CollectionObject", name)) {
+		return "GroupObject";
+	}
+	return name;
+}
+
+const char *DNA_struct_rename_legacy_hack_alias_from_static(const char *name)
+{
+	/* 'bScreen' replaces the old IrisGL 'Screen' struct */
+	if (STREQ("Screen", name)) {
+		return "bScreen";
+	}
+	/* Groups renamed to collections in 2.8 */
+	if (STREQ("Group", name)) {
+		return "Collection";
+	}
+	if (STREQ("GroupObject", name)) {
+		return "CollectionObject";
+	}
+	return name;
+}
+
+/** \} */

source/blender/makesdna/intern/dna_utils.h

@@ -50,4 +50,7 @@ void DNA_alias_maps(
         enum eDNA_RenameDir version_dir,
         struct GHash **r_struct_map, struct GHash **r_elem_map);
 
+const char *DNA_struct_rename_legacy_hack_alias_from_static(const char *name);
+const char *DNA_struct_rename_legacy_hack_static_from_alias(const char *name);
+
 #endif /* __DNA_UTILS_H__ */

source/blender/makesrna/intern/rna_collection.c

@@ -303,8 +303,6 @@ void RNA_def_collections(BlenderRNA *brna)
 	PropertyRNA *prop;
 
 	srna = RNA_def_struct(brna, "Collection", "ID");
-	/* XXX: CAN WE RENAME TO Collection? */
-	RNA_def_struct_sdna(srna, "Group"); /* it is actually Collection but for 2.8 the dna is patched! */
 	RNA_def_struct_ui_text(srna, "Collection", "Collection of Object data-blocks");
 	RNA_def_struct_ui_icon(srna, ICON_GROUP);
 	/* this is done on save/load in readfile.c, removed if no objects are in the collection and not in a scene */

source/blender/makesrna/intern/rna_define.c

@@ -172,6 +172,20 @@ static void rna_brna_structs_remove_and_free(BlenderRNA *brna, StructRNA *srna)
 }
 #endif
 
+
+static int DNA_struct_find_nr_wrapper(const struct SDNA *sdna, const char *struct_name)
+{
+	struct_name = DNA_struct_rename_legacy_hack_static_from_alias(struct_name);
+#ifdef RNA_RUNTIME
+	/* We may support this at some point but for now we don't. */
+	BLI_assert(0);
+#else
+	struct_name = BLI_ghash_lookup_default(
+	        g_version_data.struct_map_static_from_alias, struct_name, (void *)struct_name);
+#endif
+	return DNA_struct_find_nr(sdna, struct_name);
+}
+
 StructDefRNA *rna_find_struct_def(StructRNA *srna)
 {
 	StructDefRNA *dsrna;
@@ -368,18 +382,7 @@ static int rna_find_sdna_member(SDNA *sdna, const char *structname, const char *
 		CLOG_ERROR(&LOG, "only during preprocessing.");
 		return 0;
 	}
-
-#ifndef RNA_RUNTIME
-	{
-		const char *structname_maybe_static = BLI_ghash_lookup_default(
-		        g_version_data.struct_map_static_from_alias, structname, (void *)structname);
-		structnr = DNA_struct_find_nr(sdna, structname_maybe_static);
-	}
-#else
-	/* Quiet warning only, this is only for the proprocessor. */
-	BLI_assert(0);
-	structnr = -1;
-#endif
+	structnr = DNA_struct_find_nr_wrapper(sdna, structname);
 
 	if (structnr == -1)
 		return 0;
@@ -926,7 +929,7 @@ void RNA_def_struct_sdna(StructRNA *srna, const char *structname)
 	/* there are far too many structs which initialize without valid DNA struct names,
 	 * this can't be checked without adding an option to disable (tested this and it means changes all over - Campbell) */
 #if 0
-	if (DNA_struct_find_nr(DefRNA.sdna, structname) == -1) {
+	if (DNA_struct_find_nr_wrapper(DefRNA.sdna, structname) == -1) {
 		if (!DefRNA.silent) {
 			CLOG_ERROR(&LOG, "%s not found.", structname);
 			DefRNA.error = 1;
@@ -954,7 +957,7 @@ void RNA_def_struct_sdna_from(StructRNA *srna, const char *structname, const cha
 		return;
 	}
 
-	if (DNA_struct_find_nr(DefRNA.sdna, structname) == -1) {
+	if (DNA_struct_find_nr_wrapper(DefRNA.sdna, structname) == -1) {
 		if (!DefRNA.silent) {
 			CLOG_ERROR(&LOG, "%s not found.", structname);
 			DefRNA.error = 1;