feat(:source, nvim_exec): defer script item creation until s:var access

For anonymous scripts, defer the creation of script items until an attempt to access a script-local
variable is made. This dramatically reduces the number of script items created when using lots of
vim.cmd and nvim_exec especially.

This will mean <SID> usage fails until a script-local variable access is first made.

src/nvim/eval.c

@@ -9191,8 +9191,12 @@ static hashtab_T *find_var_ht_dict(const char *name, const size_t name_len, cons
   } else if (*name == 'l' && funccal != NULL) {  // local variable
     *d = &funccal->l_vars;
   } else if (*name == 's'  // script variable
-             && current_sctx.sc_sid > 0
+             && (current_sctx.sc_sid > 0 || current_sctx.sc_sid == SID_STR)
              && current_sctx.sc_sid <= ga_scripts.ga_len) {
+    // For anonymous scripts without a script item, create one now so script vars can be used
+    if (current_sctx.sc_sid == SID_STR) {
+      new_script_item(NULL, &current_sctx.sc_sid);
+    }
     *d = &SCRIPT_SV(current_sctx.sc_sid)->sv_dict;
   }
 

src/nvim/ex_cmds2.c

@@ -52,33 +52,7 @@
 #include "nvim/version.h"
 #include "nvim/window.h"
 
-
 /// Growarray to store info about already sourced scripts.
-/// Also store the dev/ino, so that we don't have to stat() each
-/// script when going through the list.
-typedef struct scriptitem_S {
-  char_u *sn_name;
-  bool file_id_valid;
-  FileID file_id;
-  bool sn_prof_on;              ///< true when script is/was profiled
-  bool sn_pr_force;             ///< forceit: profile functions in this script
-  proftime_T sn_pr_child;       ///< time set when going into first child
-  int sn_pr_nest;               ///< nesting for sn_pr_child
-  // profiling the script as a whole
-  int sn_pr_count;              ///< nr of times sourced
-  proftime_T sn_pr_total;       ///< time spent in script + children
-  proftime_T sn_pr_self;        ///< time spent in script itself
-  proftime_T sn_pr_start;       ///< time at script start
-  proftime_T sn_pr_children;    ///< time in children after script start
-  // profiling the script per line
-  garray_T sn_prl_ga;           ///< things stored for every line
-  proftime_T sn_prl_start;      ///< start time for current line
-  proftime_T sn_prl_children;   ///< time spent in children for this line
-  proftime_T sn_prl_wait;       ///< wait start time for current line
-  linenr_T sn_prl_idx;          ///< index of line being timed; -1 if none
-  int sn_prl_execed;            ///< line being timed was executed
-} scriptitem_T;
-
 static garray_T script_items = { 0, 0, sizeof(scriptitem_T), 4, NULL };
 #define SCRIPT_ITEM(id) (((scriptitem_T *)script_items.ga_data)[(id) - 1])
 
@@ -1944,7 +1918,7 @@ static char_u *get_str_line(int c, void *cookie, int indent, bool do_concat)
 /// @param  name  File name of the script. NULL for anonymous :source.
 /// @param[out]  sid_out  SID of the new item.
 /// @return pointer to the created script item.
-static scriptitem_T *new_script_item(char_u *const name, scid_T *const sid_out)
+scriptitem_T *new_script_item(char_u *const name, scid_T *const sid_out)
 {
   static scid_T last_current_SID = 0;
   const scid_T sid = ++last_current_SID;
@@ -1978,7 +1952,7 @@ static int source_using_linegetter(void *cookie, LineGetter fgetline, const char
   sourcing_lnum = 0;
 
   const sctx_T save_current_sctx = current_sctx;
-  new_script_item(NULL, &current_sctx.sc_sid);
+  current_sctx.sc_sid = SID_STR;
   current_sctx.sc_seq = 0;
   current_sctx.sc_lnum = save_sourcing_lnum;
   funccal_entry_T entry;

src/nvim/ex_cmds2.h

@@ -16,6 +16,31 @@
 #define CCGD_ALLBUF     8       // may write all buffers
 #define CCGD_EXCMD      16      // may suggest using !
 
+/// Also store the dev/ino, so that we don't have to stat() each
+/// script when going through the list.
+typedef struct scriptitem_S {
+  char_u *sn_name;
+  bool file_id_valid;
+  FileID file_id;
+  bool sn_prof_on;              ///< true when script is/was profiled
+  bool sn_pr_force;             ///< forceit: profile functions in this script
+  proftime_T sn_pr_child;       ///< time set when going into first child
+  int sn_pr_nest;               ///< nesting for sn_pr_child
+  // profiling the script as a whole
+  int sn_pr_count;              ///< nr of times sourced
+  proftime_T sn_pr_total;       ///< time spent in script + children
+  proftime_T sn_pr_self;        ///< time spent in script itself
+  proftime_T sn_pr_start;       ///< time at script start
+  proftime_T sn_pr_children;    ///< time in children after script start
+  // profiling the script per line
+  garray_T sn_prl_ga;           ///< things stored for every line
+  proftime_T sn_prl_start;      ///< start time for current line
+  proftime_T sn_prl_children;   ///< time spent in children for this line
+  proftime_T sn_prl_wait;       ///< wait start time for current line
+  linenr_T sn_prl_idx;          ///< index of line being timed; -1 if none
+  int sn_prl_execed;            ///< line being timed was executed
+} scriptitem_T;
+
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "ex_cmds2.h.generated.h"
 #endif

test/functional/api/vim_spec.lua

@@ -89,6 +89,14 @@ describe('API', function()
 
     it(':verbose set {option}?', function()
       nvim('exec', 'set nowrap', false)
+      eq('nowrap\n\tLast set from anonymous :source',
+        nvim('exec', 'verbose set wrap?', true))
+
+      -- Using script var to force creation of a script item
+      nvim('exec', [[
+        let s:a = 1
+        set nowrap
+      ]], false)
       eq('nowrap\n\tLast set from anonymous :source (script id 1)',
         nvim('exec', 'verbose set wrap?', true))
     end)
@@ -155,6 +163,20 @@ describe('API', function()
           let s:pirate = 'script-scoped varrrrr'
           call nvim_exec('echo s:pirate', 1)
         ]], false))
+
+      -- Script items are created only on script var access
+      eq('1\n0', nvim('exec', [[
+          echo expand("<SID>")->empty()
+          let s:a = 123
+          echo expand("<SID>")->empty()
+        ]], true))
+
+      eq('1\n0', nvim('exec', [[
+          echo expand("<SID>")->empty()
+          function s:a() abort
+          endfunction
+          echo expand("<SID>")->empty()
+        ]], true))
     end)
 
     it('non-ASCII input', function()

test/functional/ex_cmds/source_spec.lua

@@ -26,13 +26,17 @@ describe(':source', function()
         \ k: "v"
        "\ (o_o)
         \ }
+      let c = expand("<SID>")->empty()
       let s:s = 0zbeef.cafe
-      let c = s:s]])
+      let d = s:s]])
 
     command('source')
     eq('2', meths.exec('echo a', true))
     eq("{'k': 'v'}", meths.exec('echo b', true))
-    eq("0zBEEFCAFE", meths.exec('echo c', true))
+
+    -- Script items are created only on script var access
+    eq("1", meths.exec('echo c', true))
+    eq("0zBEEFCAFE", meths.exec('echo d', true))
 
     exec('set cpoptions+=C')
     eq('Vim(let):E15: Invalid expression: #{', exc_exec('source'))
@@ -62,7 +66,7 @@ describe(':source', function()
     feed_command(':source')
     eq('4', meths.exec('echo a', true))
     eq("{'K': 'V'}", meths.exec('echo b', true))
-    eq("<SNR>3_C()", meths.exec('echo D()', true))
+    eq("<SNR>1_C()", meths.exec('echo D()', true))
 
     -- Source last line only
     feed_command(':$source')