From 3124d4be96b7cfd129b45f501c97c08b6d41db62 Mon Sep 17 00:00:00 2001
From: Nyall Dawson <nyall.dawson@gmail.com>
Date: Thu, 11 Jul 2024 11:57:26 +1000
Subject: [PATCH] [GRASS] Fix writing projection for new mapsets

Use the more modern API so that the projection SRID and WKT
are written losslessly to the mapset

Avoids loss of projection information when creating
mapsets
---
 src/plugins/grass/qgsgrassnewmapset.cpp | 23 ++++++++++++-----------
 src/plugins/grass/qgsgrassnewmapset.h   |  2 ++
 2 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/src/plugins/grass/qgsgrassnewmapset.cpp b/src/plugins/grass/qgsgrassnewmapset.cpp
index 99ecd6ee9b07..df3896cc666d 100644
--- a/src/plugins/grass/qgsgrassnewmapset.cpp
+++ b/src/plugins/grass/qgsgrassnewmapset.cpp
@@ -399,18 +399,9 @@ void QgsGrassNewMapset::setGrassProjection()
     const QString wkt = crs.toWkt( QgsCoordinateReferenceSystem::WktVariant::WKT_PREFERRED );
     QgsDebugMsgLevel( QStringLiteral( "wkt = %1" ).arg( crs.toWkt( Qgis::CrsWktVariant::Preferred ) ), 3 );
 
-    // Note: GPJ_osr_to_grass() defaults in PROJECTION_XY if projection
-    //       cannot be set
-
     G_TRY
     {
-      // There was a bug in GRASS, it is present in 6.0.x line
-      int ret = GPJ_wkt_to_grass( &mCellHead, &mProjInfo, &mProjUnits, wkt.toUtf8().constData(), 0 );
-      // Note: It seems that GPJ_osr_to_grass()returns always 1,
-      //   -> test if mProjInfo was set
-
-      Q_UNUSED( ret )
-      QgsDebugMsgLevel( QString( "ret = %1" ).arg( ret ), 2 );
+      GPJ_wkt_to_grass( &mCellHead, &mProjInfo, &mProjUnits, wkt.toUtf8().constData(), 0 );
     }
     G_CATCH( QgsGrass::Exception & e )
     {
@@ -422,6 +413,11 @@ void QgsGrassNewMapset::setGrassProjection()
     {
       setError( mProjErrorLabel, tr( "Selected projection is not supported by GRASS!" ) );
     }
+    else
+    {
+      mProjSrid = crs.authid().toUpper();
+      mProjWkt = wkt;
+    }
   }
   else // Nothing selected
   {
@@ -429,6 +425,8 @@ void QgsGrassNewMapset::setGrassProjection()
     mCellHead.zone = 0;
     mProjInfo = nullptr;
     mProjUnits = nullptr;
+    mProjSrid.clear();
+    mProjWkt.clear();
   }
   button( QWizard::NextButton )->setEnabled( mProjInfo && mProjUnits );
 }
@@ -1106,7 +1104,10 @@ void QgsGrassNewMapset::createMapset()
     QString error;
     G_TRY
     {
-      ret = G_make_location( location.toUtf8().constData(), &mCellHead, mProjInfo, mProjUnits );
+      ret = G_make_location_crs( location.toUtf8().constData(),
+                                 &mCellHead, mProjInfo, mProjUnits,
+                                 mProjSrid.toUtf8().constData(),
+                                 mProjWkt.toUtf8().constData() );
     }
     G_CATCH( QgsGrass::Exception & e )
     {
diff --git a/src/plugins/grass/qgsgrassnewmapset.h b/src/plugins/grass/qgsgrassnewmapset.h
index 4c34e01a34be..0d423290ef6e 100644
--- a/src/plugins/grass/qgsgrassnewmapset.h
+++ b/src/plugins/grass/qgsgrassnewmapset.h
@@ -195,6 +195,8 @@ class QgsGrassNewMapset : public QWizard, private Ui::QgsGrassNewMapsetBase
     struct Cell_head mCellHead;
     struct Key_Value *mProjInfo = nullptr;
     struct Key_Value *mProjUnits = nullptr;
+    QString mProjSrid;
+    QString mProjWkt;
 
     //! Previous page
     int mPreviousPage = -1;