[RFC] ":source" sources from current buffer if filename is omitted (#11444)

Fix https://github.com/neovim/neovim/issues/8722

src/nvim/ex_cmds.lua

@@ -2521,8 +2521,8 @@ module.cmds = {
   },
   {
     command='source',
-    flags=bit.bor(BANG, FILE1, TRLBAR, SBOXOK, CMDWIN),
+    flags=bit.bor(RANGE, DFLALL, WHOLEFOLD, BANG, FILE1, TRLBAR, SBOXOK, CMDWIN),
-    addr_type='ADDR_NONE',
+    addr_type='ADDR_LINES',
     func='ex_source',
   },
   {

src/nvim/ex_cmds2.c

@@ -29,6 +29,7 @@
 #include "nvim/getchar.h"
 #include "nvim/mark.h"
 #include "nvim/mbyte.h"
+#include "nvim/memline.h"
 #include "nvim/message.h"
 #include "nvim/misc1.h"
 #include "nvim/garray.h"
@@ -2526,7 +2527,7 @@ void ex_pyxdo(exarg_T *eap)
   }
 }
 
-/// ":source {fname}"
+/// ":source [{fname}]"
 void ex_source(exarg_T *eap)
 {
   cmd_source(eap->arg, eap);
@@ -2535,7 +2536,7 @@ void ex_source(exarg_T *eap)
 static void cmd_source(char_u *fname, exarg_T *eap)
 {
   if (*fname == NUL) {
-    EMSG(_(e_argreq));
+    cmd_source_buffer(eap);
   } else if (eap != NULL && eap->forceit) {
     // ":source!": read Normal mode commands
     // Need to execute the commands directly.  This is required at least
@@ -2553,6 +2554,37 @@ static void cmd_source(char_u *fname, exarg_T *eap)
   }
 }
 
+typedef struct {
+  linenr_T curr_lnum;
+  const linenr_T final_lnum;
+} GetBufferLineCookie;
+
+/// Get one line from the current selection in the buffer.
+/// Called by do_cmdline() when it's called from cmd_source_buffer().
+///
+/// @return pointer to allocated line, or NULL for end-of-file or
+///         some error.
+static char_u *get_buffer_line(int c, void *cookie, int indent, bool do_concat)
+{
+  GetBufferLineCookie *p = cookie;
+  if (p->curr_lnum > p->final_lnum) {
+    return NULL;
+  }
+  char_u *curr_line = ml_get(p->curr_lnum);
+  p->curr_lnum++;
+  return (char_u *)xstrdup((const char *)curr_line);
+}
+
+static void cmd_source_buffer(exarg_T *eap)
+{
+  GetBufferLineCookie cookie = {
+      .curr_lnum = eap->line1,
+      .final_lnum = eap->line2,
+  };
+  source_using_linegetter((void *)&cookie, get_buffer_line,
+                          ":source (no file)");
+}
+
 /// ":source" and associated commands.
 ///
 /// @return address holding the next breakpoint line for a source cookie
@@ -2624,10 +2656,9 @@ static char_u *get_str_line(int c, void *cookie, int indent, bool do_concat)
   return (char_u *)xstrdup(buf);
 }
 
-/// Executes lines in `src` as Ex commands.
+static int source_using_linegetter(void *cookie,
-///
+                                   LineGetter fgetline,
-/// @see do_source()
+                                   const char *traceback_name)
-int do_source_str(const char *cmd, const char *traceback_name)
 {
   char_u *save_sourcing_name = sourcing_name;
   linenr_T save_sourcing_lnum = sourcing_lnum;
@@ -2642,22 +2673,33 @@ int do_source_str(const char *cmd, const char *traceback_name)
   }
   sourcing_lnum = 0;
 
-  GetStrLineCookie cookie = {
-    .buf = (char_u *)cmd,
-    .offset = 0,
-  };
   const sctx_T save_current_sctx = current_sctx;
   current_sctx.sc_sid = SID_STR;
   current_sctx.sc_seq = 0;
   current_sctx.sc_lnum = save_sourcing_lnum;
-  int retval = do_cmdline(NULL, get_str_line, (void *)&cookie,
+  funccal_entry_T entry;
+  save_funccal(&entry);
+  int retval = do_cmdline(NULL, fgetline, cookie,
                           DOCMD_VERBOSE | DOCMD_NOWAIT | DOCMD_REPEAT);
-  current_sctx = save_current_sctx;
   sourcing_lnum = save_sourcing_lnum;
   sourcing_name = save_sourcing_name;
+  current_sctx = save_current_sctx;
+  restore_funccal();
   return retval;
 }
 
+/// Executes lines in `src` as Ex commands.
+///
+/// @see do_source()
+int do_source_str(const char *cmd, const char *traceback_name)
+{
+  GetStrLineCookie cookie = {
+      .buf = (char_u *)cmd,
+      .offset = 0,
+  };
+  return source_using_linegetter((void *)&cookie, get_str_line, traceback_name);
+}
+
 /// Reads the file `fname` and executes its lines as Ex commands.
 ///
 /// This function may be called recursively!

test/functional/ex_cmds/source_spec.lua

@@ -0,0 +1,47 @@
+local helpers = require('test.functional.helpers')(after_each)
+local command = helpers.command
+local insert = helpers.insert
+local eq = helpers.eq
+local clear = helpers.clear
+local meths = helpers.meths
+local feed = helpers.feed
+local feed_command = helpers.feed_command
+
+describe(':source', function()
+  before_each(function()
+    clear()
+  end)
+
+  it('current buffer', function()
+    insert('let a = 2')
+    command('source')
+    eq('2', meths.exec('echo a', true))
+  end)
+
+  it('selection in current buffer', function()
+    insert(
+      'let a = 2\n'..
+      'let a = 3\n'..
+      'let a = 4\n')
+
+    -- Source the 2nd line only
+    feed('ggjV')
+    feed_command(':source')
+    eq('3', meths.exec('echo a', true))
+
+    -- Source from 2nd line to end of file
+    feed('ggjVG')
+    feed_command(':source')
+    eq('4', meths.exec('echo a', true))
+  end)
+
+  it('multiline heredoc command', function()
+    insert(
+      'lua << EOF\n'..
+      'y = 4\n'..
+      'EOF\n')
+
+    command('source')
+    eq('4', meths.exec('echo luaeval("y")', true))
+  end)
+end)