RNA: Generate property declerations header, solving msg-bus C++ incompatibility

Lets `makesrna` generate a `RNA_prototypes.h` header with declarations for all
RNA properties. This can be included in regular source files when needing to
reference RNA properties statically.

This solves an issue on MSVC with adding such declarations in functions, like
we used to do. See 800fc1736748. Removes any such declarations and the related
FIXME comments.

Reviewed By: campbellbarton, LazyDodo, brecht

Differential Revision: https://developer.blender.org/D13837

1 files changed, 57 insertions, 8 deletions

diff --git a/source/blender/makesrna/intern/makesrna.c b/source/blender/makesrna/intern/makesrna.c
index 3ea7f8e0df6..f19bab6870a 100644
--- a/source/blender/makesrna/intern/makesrna.c
+++ b/source/blender/makesrna/intern/makesrna.c
@@ -3304,7 +3304,7 @@ static const char *rna_property_subtype_unit(PropertySubType type)
   }
 }
 
-static void rna_generate_prototypes(BlenderRNA *brna, FILE *f)
+static void rna_generate_internal_struct_prototypes(BlenderRNA *brna, FILE *f)
 {
   StructRNA *srna;
 
@@ -3343,7 +3343,19 @@ static void rna_generate_blender(BlenderRNA *brna, FILE *f)
           "};\n\n");
 }
 
-static void rna_generate_property_prototypes(BlenderRNA *UNUSED(brna), StructRNA *srna, FILE *f)
+static void rna_generate_external_property_prototypes(BlenderRNA *brna, FILE *f)
+{
+  for (StructRNA *srna = brna->structs.first; srna; srna = srna->cont.next) {
+    for (PropertyRNA *prop = srna->cont.properties.first; prop; prop = prop->next) {
+      fprintf(f, "extern struct PropertyRNA rna_%s_%s;\n", srna->identifier, prop->identifier);
+    }
+    fprintf(f, "\n");
+  }
+}
+
+static void rna_generate_internal_property_prototypes(BlenderRNA *UNUSED(brna),
+                                                      StructRNA *srna,
+                                                      FILE *f)
 {
   PropertyRNA *prop;
   StructRNA *base;
@@ -4499,7 +4511,7 @@ static void rna_generate(BlenderRNA *brna, FILE *f, const char *filename, const
 
   for (ds = DefRNA.structs.first; ds; ds = ds->cont.next) {
     if (!filename || ds->filename == filename) {
-      rna_generate_property_prototypes(brna, ds->srna, f);
+      rna_generate_internal_property_prototypes(brna, ds->srna, f);
       rna_generate_function_prototypes(brna, ds->srna, f);
     }
   }
@@ -5128,7 +5140,11 @@ static void make_bad_file(const char *file, int line)
   fclose(fp);
 }
 
-static int rna_preprocess(const char *outfile)
+/**
+ * \param extern_outfile: Directory to put public headers into. Can be NULL, in which case
+ *                        everything is put into \a outfile.
+ */
+static int rna_preprocess(const char *outfile, const char *public_header_outfile)
 {
   BlenderRNA *brna;
   StructDefRNA *ds;
@@ -5137,6 +5153,10 @@ static int rna_preprocess(const char *outfile)
   int i, status;
   const char *deps[3]; /* expand as needed */
 
+  if (!public_header_outfile) {
+    public_header_outfile = outfile;
+  }
+
   /* define rna */
   brna = RNA_create();
 
@@ -5161,7 +5181,36 @@ static int rna_preprocess(const char *outfile)
 
   status = (DefRNA.error != 0);
 
-  /* create rna prototype header file */
+  /* Create external rna struct prototype header file RNA_prototypes.h. */
+  strcpy(deffile, public_header_outfile);
+  strcat(deffile, "RNA_prototypes.h" TMP_EXT);
+  if (status) {
+    make_bad_file(deffile, __LINE__);
+  }
+  file = fopen(deffile, "w");
+  if (!file) {
+    fprintf(stderr, "Unable to open file: %s\n", deffile);
+    status = 1;
+  }
+  else {
+    fprintf(file,
+            "/* Automatically generated RNA property declarations, to statically reference \n"
+            " * properties as `rna_[struct-name]_[property-name]`.\n"
+            " *\n"
+            " * DO NOT EDIT MANUALLY, changes will be overwritten.\n"
+            " */\n\n");
+
+    fprintf(file, "#pragma once\n\n");
+    fprintf(file, "#ifdef __cplusplus\n  extern \"C\" {\n#endif\n\n");
+    rna_generate_external_property_prototypes(brna, file);
+    fprintf(file, "#ifdef __cplusplus\n  }\n#endif\n");
+    fclose(file);
+    status = (DefRNA.error != 0);
+
+    replace_if_different(deffile, NULL);
+  }
+
+  /* create internal rna struct prototype header file */
   strcpy(deffile, outfile);
   strcat(deffile, "rna_prototypes_gen.h");
   if (status) {
@@ -5176,7 +5225,7 @@ static int rna_preprocess(const char *outfile)
     fprintf(file,
             "/* Automatically generated function declarations for the Data API.\n"
             " * Do not edit manually, changes will be overwritten.              */\n\n");
-    rna_generate_prototypes(brna, file);
+    rna_generate_internal_struct_prototypes(brna, file);
     fclose(file);
     status = (DefRNA.error != 0);
   }
@@ -5288,7 +5337,7 @@ int main(int argc, char **argv)
   CLG_level_set(debugSRNA);
 
   if (argc < 2) {
-    fprintf(stderr, "Usage: %s outdirectory/\n", argv[0]);
+    fprintf(stderr, "Usage: %s outdirectory [public header outdirectory]/\n", argv[0]);
     return_status = 1;
   }
   else {
@@ -5296,7 +5345,7 @@ int main(int argc, char **argv)
       fprintf(stderr, "Running makesrna\n");
     }
     makesrna_path = argv[0];
-    return_status = rna_preprocess(argv[1]);
+    return_status = rna_preprocess(argv[1], (argc > 2) ? argv[2] : NULL);
   }
 
   CLG_exit();