eval: Add ability to set the unnamed register with setreg

3 files changed, 29 insertions, 1 deletions

diff --git a/runtime/doc/eval.txt b/runtime/doc/eval.txt
index f076458fed..f73599ebd9 100644
--- a/runtime/doc/eval.txt
+++ b/runtime/doc/eval.txt
@@ -6710,6 +6710,8 @@ setreg({regname}, {value} [, {options}])
 		used as the width of the selection - if it is not specified
 		then the width of the block is set to the number of characters
 		in the longest line (counting a <Tab> as 1 character).
+		If {options} contains "u" or '"', then the unnamed register is
+		set to point to register {regname}.
 
 		If {options} contains no register settings, then the default
 		is to use character mode unless {value} ends in a <NL> for 
diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index e4b3128930..473de02ab6 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -5100,7 +5100,8 @@ bool garbage_collect(bool testing)
     do {
       yankreg_T reg;
       char name = NUL;
-      reg_iter = op_register_iter(reg_iter, &name, &reg);
+      bool is_unnamed = false;
+      reg_iter = op_register_iter(reg_iter, &name, &reg, &is_unnamed);
       if (name != NUL) {
         ABORTING(set_ref_dict)(reg.additional_data, copyID);
       }
@@ -14792,6 +14793,7 @@ static void f_setreg(typval_T *argvars, typval_T *rettv, FunPtr fptr)
     regname = '"';
   }
 
+  bool set_unnamed = false;
   if (argvars[2].v_type != VAR_UNKNOWN) {
     const char *stropt = tv_get_string_chk(&argvars[2]);
     if (stropt == NULL) {
@@ -14820,6 +14822,10 @@ static void f_setreg(typval_T *argvars, typval_T *rettv, FunPtr fptr)
           }
           break;
         }
+        case 'u': case '"': { // unnamed register
+          set_unnamed = true;
+          break;
+        }
       }
     }
   }
@@ -14872,6 +14878,10 @@ free_lstval:
                           append, yank_type, block_len);
   }
   rettv->vval.v_number = 0;
+
+  if (set_unnamed) {
+    op_register_set_previous(regname);
+  }
 }
 
 /*
diff --git a/src/nvim/ops.c b/src/nvim/ops.c
index 9e5121b3fe..90d9d41a2a 100644
--- a/src/nvim/ops.c
+++ b/src/nvim/ops.c
@@ -5853,3 +5853,19 @@ const yankreg_T *op_register_get(const char name)
   }
   return &y_regs[i];
 }
+
+/// Set the previous yank register
+///
+/// @param[in]  name  Register name.
+///
+/// @return true on success, false on failure.
+bool op_register_set_previous(const char name)
+{
+  int i = op_reg_index(name);
+  if (i == -1) {
+    return false;
+  }
+
+  y_previous = &y_regs[i];
+  return true;
+}