Save note: a DWG loses SAT-text solids from 2013 on, and the note says so (#2334)

A real DWG write and read-back keeps a SAT-text REGION's groups up to 2010 and
returns it without them at 2013 and 2018, so the SAT-text skip in not_saved_as
applies before 2013 only. The DWG note now says solids are kept in a DXF only
when saved as 2010 or earlier.

crates/engine/src/cmd/file.rs

@@ -550,10 +550,10 @@ pub fn not_saved_as(d: &Drawing, version: Version) -> std::collections::BTreeMap
     let stores = std::iter::once(&d.model).chain(d.layouts.iter().map(|l| &l.entities)).chain(d.blocks.values().map(|b| &b.entities));
     for e in stores.flat_map(|s| s.iter()) {
         if let cadcraft_doc::EntityKind::Unknown(u) = &e.kind {
-            // A DWG writer converts SAT text to its own form at any version, and from 2013 a data
-            // store record keeps the geometry too: neither loses the solid.
+            // A DWG before 2013 writes a solid's SAT text as it is; from 2013 the geometry has to be
+            // in the data store, and SAT text alone is lost (#2334).
             if MODELER_TYPES.iter().any(|t| u.dxf_type.eq_ignore_ascii_case(t))
-                && (stored.contains(&e.handle) || cadcraft_doc::foreign::has_sat_text(&u.tags))
+                && (stored.contains(&e.handle) || (version < Version::R2013 && cadcraft_doc::foreign::has_sat_text(&u.tags)))
             {
                 continue;
             }
@@ -570,7 +570,10 @@ pub fn not_saved_message(lost: &std::collections::BTreeMap<String, usize>) -> Op
         return None;
     }
     let list: Vec<String> = lost.iter().map(|(t, n)| format!("{n} {t}")).collect();
-    Some(format!("Not saved in the DWG file (its writer can't write these object types yet; DXF keeps them): {}", list.join(", ")))
+    Some(format!(
+        "Not saved in the DWG file (its writer can't write these object types yet; DXF keeps them, solids only when saved as 2010 or earlier): {}",
+        list.join(", ")
+    ))
 }
 
 /// Whether saving to `path` leaves out the entities [`not_saved`] counts: DWG does (the DWG

crates/engine/tests/save_reports_not_saved.rs

@@ -29,7 +29,7 @@ fn save_lists_the_entities_the_file_does_not_keep() {
     let r = s.execute("saveas", &json!({ "path": path.to_string_lossy() })).unwrap();
     let _ = std::fs::remove_file(&path);
     assert_eq!(r["notSaved"], json!({ "3DSOLID": 1, "MLINE": 2, "REGION": 1 }));
-    let msg = "Not saved in the DWG file (its writer can't write these object types yet; DXF keeps them): 1 3DSOLID, 2 MLINE, 1 REGION";
+    let msg = "Not saved in the DWG file (its writer can't write these object types yet; DXF keeps them, solids only when saved as 2010 or earlier): 1 3DSOLID, 2 MLINE, 1 REGION";
     assert!(s.log.iter().any(|l| l == msg), "{:?}", s.log);
 
     // DXF keeps them.
@@ -145,17 +145,17 @@ fn the_note_counts_the_host_drawing_while_a_block_is_edited() {
     assert_eq!(r["notSaved"], json!({ "REGION": 1 }));
 }
 
-/// A DWG writer converts a solid's SAT text itself (at any version), so a DWG save doesn't list
-/// solids that hold it as left out; ones with neither SAT text nor a data store record are (#2334).
+/// A DWG before 2013 writes a solid's SAT text as it is, so a save there doesn't list a solid that
+/// holds it; from 2013 the geometry must be in the data store and SAT text alone is lost, so the
+/// save lists it. A solid with neither is always listed (#2334).
 #[test]
-fn a_dwg_keeps_solids_that_hold_sat_text() {
+fn a_dwg_keeps_sat_text_solids_only_before_2013() {
     use cadcraft_engine::cmd::file::{Version, not_saved_as};
     let tag = |code: i32, value: &str| RawTag { code, value: value.into() };
     let solid = |tags: Vec<RawTag>| EntityKind::Unknown(Unknown { dxf_type: "3DSOLID".into(), tags });
     let mut d = Drawing::new_imperial();
     d.add(&Space::Model, Common::default(), solid(vec![tag(100, "AcDbModelerGeometry"), tag(1, "400 1 1 0")])).unwrap();
     d.add(&Space::Model, Common::default(), solid(vec![tag(100, "AcDbModelerGeometry"), tag(70, "1")])).unwrap();
-    for v in [Version::R2010, Version::R2018] {
-        assert_eq!(not_saved_as(&d, v), [("3DSOLID".to_string(), 1)].into_iter().collect(), "{v:?}");
-    }
+    assert_eq!(not_saved_as(&d, Version::R2010), [("3DSOLID".to_string(), 1)].into_iter().collect(), "2010 keeps the SAT-text solid");
+    assert_eq!(not_saved_as(&d, Version::R2018), [("3DSOLID".to_string(), 2)].into_iter().collect(), "2018 loses it");
 }

crates/io/tests/it/acis_data_store.rs

@@ -196,3 +196,24 @@ fn a_data_store_record_stores_only_its_first_entity() {
     let store = Foreign { data_store: vec![tag(0, "ACDSRECORD"), tag(320, "2B"), tag(320, "2C"), tag(2, "ASM_Data")], ..Foreign::default() };
     assert_eq!(store.data_store_entities(), [Handle(0x2B)].into());
 }
+
+/// A real DWG round trip of a SAT-text REGION: the DWG writer keeps the SAT groups up to 2010, and
+/// from 2013 they come back empty (the solid's geometry is not in the file), which the DWG save
+/// note has to say (#2334).
+#[test]
+fn a_dwg_keeps_a_sat_text_region_only_before_2013() {
+    let sat = "0\nSECTION\n2\nHEADER\n9\n$ACADVER\n1\nAC1015\n0\nENDSEC\n0\nSECTION\n2\nENTITIES\n\
+        0\nREGION\n5\n2B\n100\nAcDbEntity\n8\n0\n100\nAcDbModelerGeometry\n70\n1\n1\n400 1 1 0\n3\nEnd-of-ACIS-data\n0\nENDSEC\n0\nEOF\n";
+    let d = cadcraft_io::read_dxf(sat.as_bytes()).unwrap();
+    let holds_sat = |v: cadcraft_io::Version| {
+        let dwg = cadcraft_io::write_with(&d, "x.dwg", &cadcraft_io::SaveOptions { version: Some(v), binary: false }).unwrap();
+        let back = cadcraft_io::read(&dwg, "x.dwg").unwrap();
+        let region = back.model.iter().find_map(|e| match &e.kind {
+            EntityKind::Unknown(u) if u.dxf_type == "REGION" => Some(u.clone()),
+            _ => None,
+        });
+        region.is_some_and(|u| cadcraft_doc::foreign::has_sat_text(&u.tags))
+    };
+    assert!(holds_sat(cadcraft_io::Version::R2010), "2010 keeps the SAT text");
+    assert!(!holds_sat(cadcraft_io::Version::R2018), "2018 comes back without it");
+}