fix(exceptions): restore did_throw (#20000)

`!did_throw` doesn't exactly imply `!current_exception`, as `did_throw = false`
is sometimes used to defer exception handling for later (without forgetting the
exception). E.g: uncaught exception handling in `do_cmdline()` may be deferred
to a different call (e.g: when `try_level > 0`).

In #7881, `current_exception = NULL` in `do_cmdline()` is used as an analogue of
`did_throw = false`, but also causes the pending exception to be lost, which
also leaks as `discard_exception()` wasn't used.

It may be possible to fix this by saving/restoring `current_exception`, but
handling all of `did_throw`'s edge cases seems messier. Maybe not worth
diverging over.

This fix also uncovers a `man_spec.lua` bug on Windows: exceptions are thrown
due to Windows missing `man`, but they're lost; skip these tests if `man` isn't
executable.

src/nvim/api/private/helpers.c

@@ -58,6 +58,7 @@ void try_enter(TryState *const tstate)
     .private_msg_list = NULL,
     .trylevel = trylevel,
     .got_int = got_int,
+    .did_throw = did_throw,
     .need_rethrow = need_rethrow,
     .did_emsg = did_emsg,
   };
@@ -65,6 +66,7 @@ void try_enter(TryState *const tstate)
   current_exception = NULL;
   trylevel = 1;
   got_int = false;
+  did_throw = false;
   need_rethrow = false;
   did_emsg = false;
 }
@@ -85,6 +87,7 @@ bool try_leave(const TryState *const tstate, Error *const err)
   assert(trylevel == 0);
   assert(!need_rethrow);
   assert(!got_int);
+  assert(!did_throw);
   assert(!did_emsg);
   assert(msg_list == &tstate->private_msg_list);
   assert(*msg_list == NULL);
@@ -93,6 +96,7 @@ bool try_leave(const TryState *const tstate, Error *const err)
   current_exception = tstate->current_exception;
   trylevel = tstate->trylevel;
   got_int = tstate->got_int;
+  did_throw = tstate->did_throw;
   need_rethrow = tstate->need_rethrow;
   did_emsg = tstate->did_emsg;
   return ret;
@@ -127,7 +131,7 @@ bool try_end(Error *err)
   force_abort = false;
 
   if (got_int) {
-    if (current_exception) {
+    if (did_throw) {
       // If we got an interrupt, discard the current exception
       discard_current_exception();
     }
@@ -146,7 +150,7 @@ bool try_end(Error *err)
     if (should_free) {
       xfree(msg);
     }
-  } else if (current_exception) {
+  } else if (did_throw) {
     api_set_error(err, kErrorTypeException, "%s", current_exception->value);
     discard_current_exception();
   }

src/nvim/api/private/helpers.h

@@ -134,6 +134,7 @@ typedef struct {
   const msglist_T *const *msg_list;
   int trylevel;
   int got_int;
+  bool did_throw;
   int need_rethrow;
   int did_emsg;
 } TryState;

src/nvim/api/vimscript.c

@@ -137,7 +137,7 @@ Object nvim_eval(String expr, Error *err)
     if (!recursive) {
       force_abort = false;
       suppress_errthrow = false;
-      current_exception = NULL;
+      did_throw = false;
       // `did_emsg` is set by emsg(), which cancels execution.
       did_emsg = false;
     }
@@ -196,7 +196,7 @@ static Object _call_function(String fn, Array args, dict_T *self, Error *err)
     if (!recursive) {
       force_abort = false;
       suppress_errthrow = false;
-      current_exception = NULL;
+      did_throw = false;
       // `did_emsg` is set by emsg(), which cancels execution.
       did_emsg = false;
     }

src/nvim/eval.c

@@ -5985,7 +5985,7 @@ void timer_due_cb(TimeWatcher *tw, void *data)
   // Handle error message
   if (called_emsg > called_emsg_before && did_emsg) {
     timer->emsg_count++;
-    if (current_exception != NULL) {
+    if (did_throw) {
       discard_current_exception();
     }
   }

src/nvim/eval/userfunc.c

@@ -3010,7 +3010,7 @@ void ex_call(exarg_T *eap)
 
   // When inside :try we need to check for following "| catch" or "| endtry".
   // Not when there was an error, but do check if an exception was thrown.
-  if ((!aborting() || current_exception != NULL) && (!failed || eap->cstack->cs_trylevel > 0)) {
+  if ((!aborting() || did_throw) && (!failed || eap->cstack->cs_trylevel > 0)) {
     // Check for trailing illegal characters and a following command.
     if (!ends_excmd(*arg)) {
       if (!failed && !aborting()) {

src/nvim/ex_docmd.c

@@ -134,6 +134,7 @@ struct dbg_stuff {
   char *vv_throwpoint;
   int did_emsg;
   int got_int;
+  bool did_throw;
   int need_rethrow;
   int check_cstack;
   except_T *current_exception;
@@ -165,6 +166,7 @@ static void save_dbg_stuff(struct dbg_stuff *dsp)
   // Necessary for debugging an inactive ":catch", ":finally", ":endtry".
   dsp->did_emsg       = did_emsg;             did_emsg     = false;
   dsp->got_int        = got_int;              got_int      = false;
+  dsp->did_throw      = did_throw;            did_throw    = false;
   dsp->need_rethrow   = need_rethrow;         need_rethrow = false;
   dsp->check_cstack   = check_cstack;         check_cstack = false;
   dsp->current_exception = current_exception; current_exception = NULL;
@@ -180,6 +182,7 @@ static void restore_dbg_stuff(struct dbg_stuff *dsp)
   (void)v_throwpoint(dsp->vv_throwpoint);
   did_emsg = dsp->did_emsg;
   got_int = dsp->got_int;
+  did_throw = dsp->did_throw;
   need_rethrow = dsp->need_rethrow;
   check_cstack = dsp->check_cstack;
   current_exception = dsp->current_exception;
@@ -397,7 +400,8 @@ int do_cmdline(char *cmdline, LineGetter fgetline, void *cookie, int flags)
 
   initial_trylevel = trylevel;
 
-  current_exception = NULL;
+  // "did_throw" will be set to true when an exception is being thrown.
+  did_throw = false;
   // "did_emsg" will be set to true when emsg() is used, in which case we
   // cancel the whole command line, and any if/endif or loop.
   // If force_abort is set, we cancel everything.
@@ -625,7 +629,7 @@ int do_cmdline(char *cmdline, LineGetter fgetline, void *cookie, int flags)
         // not to use a cs_line[] from an entry that isn't a ":while"
         // or ":for": It would make "current_line" invalid and can
         // cause a crash.
-        if (!did_emsg && !got_int && !current_exception
+        if (!did_emsg && !got_int && !did_throw
             && cstack.cs_idx >= 0
             && (cstack.cs_flags[cstack.cs_idx]
                 & (CSF_WHILE | CSF_FOR))
@@ -666,7 +670,7 @@ int do_cmdline(char *cmdline, LineGetter fgetline, void *cookie, int flags)
       current_line = 0;
     }
 
-    // A ":finally" makes did_emsg, got_int and current_exception pending for
+    // A ":finally" makes did_emsg, got_int and did_throw pending for
     // being restored at the ":endtry".  Reset them here and set the
     // ACTIVE and FINALLY flags, so that the finally clause gets executed.
     // This includes the case where a missing ":endif", ":endwhile" or
@@ -675,9 +679,8 @@ int do_cmdline(char *cmdline, LineGetter fgetline, void *cookie, int flags)
       cstack.cs_lflags &= ~CSL_HAD_FINA;
       report_make_pending((cstack.cs_pending[cstack.cs_idx]
                            & (CSTP_ERROR | CSTP_INTERRUPT | CSTP_THROW)),
-                          current_exception);
+                          did_throw ? current_exception : NULL);
-      did_emsg = got_int = false;
+      did_emsg = got_int = did_throw = false;
-      current_exception = NULL;
       cstack.cs_flags[cstack.cs_idx] |= CSF_ACTIVE | CSF_FINALLY;
     }
 
@@ -690,7 +693,7 @@ int do_cmdline(char *cmdline, LineGetter fgetline, void *cookie, int flags)
     // exception, cancel everything.  If it is left normally, reset
     // force_abort to get the non-EH compatible abortion behavior for
     // the rest of the script.
-    if (trylevel == 0 && !did_emsg && !got_int && !current_exception) {
+    if (trylevel == 0 && !did_emsg && !got_int && !did_throw) {
       force_abort = false;
     }
 
@@ -704,7 +707,7 @@ int do_cmdline(char *cmdline, LineGetter fgetline, void *cookie, int flags)
     // - didn't get an error message or lines are not typed
     // - there is a command after '|', inside a :if, :while, :for or :try, or
     //   looping for ":source" command or function call.
-  } while (!((got_int || (did_emsg && force_abort) || current_exception)
+  } while (!((got_int || (did_emsg && force_abort) || did_throw)
              && cstack.cs_trylevel == 0)
            && !(did_emsg
                 // Keep going when inside try/catch, so that the error can be
@@ -724,7 +727,7 @@ int do_cmdline(char *cmdline, LineGetter fgetline, void *cookie, int flags)
   if (cstack.cs_idx >= 0) {
     // If a sourced file or executed function ran to its end, report the
     // unclosed conditional.
-    if (!got_int && !current_exception
+    if (!got_int && !did_throw
         && ((getline_equal(fgetline, cookie, getsourceline)
              && !source_finished(fgetline, cookie))
             || (getline_equal(fgetline, cookie, get_func_line)
@@ -767,7 +770,8 @@ int do_cmdline(char *cmdline, LineGetter fgetline, void *cookie, int flags)
     // conditional, discard the uncaught exception, disable the conversion
     // of interrupts or errors to exceptions, and ensure that no more
     // commands are executed.
-    if (current_exception) {
+    if (did_throw) {
+      assert(current_exception != NULL);
       char *p = NULL;
       msglist_T *messages = NULL;
       msglist_T *next;
@@ -829,14 +833,14 @@ int do_cmdline(char *cmdline, LineGetter fgetline, void *cookie, int flags)
   // cstack belongs to the same function or, respectively, script file, it
   // will have to be checked for finally clauses to be executed due to the
   // ":return" or ":finish".  This is done in do_one_cmd().
-  if (current_exception) {
+  if (did_throw) {
     need_rethrow = true;
   }
   if ((getline_equal(fgetline, cookie, getsourceline)
        && ex_nesting_level > source_level(real_cookie))
       || (getline_equal(fgetline, cookie, get_func_line)
           && ex_nesting_level > func_level(real_cookie) + 1)) {
-    if (!current_exception) {
+    if (!did_throw) {
       check_cstack = true;
     }
   } else {
@@ -1675,7 +1679,7 @@ static void profile_cmd(const exarg_T *eap, cstack_T *cstack, LineGetter fgetlin
       && (!eap->skip || cstack->cs_idx == 0
           || (cstack->cs_idx > 0
               && (cstack->cs_flags[cstack->cs_idx - 1] & CSF_ACTIVE)))) {
-    int skip = did_emsg || got_int || current_exception;
+    bool skip = did_emsg || got_int || did_throw;
 
     if (eap->cmdidx == CMD_catch) {
       skip = !skip && !(cstack->cs_idx >= 0
@@ -1872,7 +1876,7 @@ static char *do_one_cmd(char **cmdlinep, int flags, cstack_T *cstack, LineGetter
 
   ea.skip = (did_emsg
              || got_int
-             || current_exception
+             || did_throw
              || (cstack->cs_idx >= 0
                  && !(cstack->cs_flags[cstack->cs_idx] & CSF_ACTIVE)));
 

src/nvim/ex_eval.c

@@ -49,16 +49,15 @@
 // interrupt (got_int) under an active try conditional terminates the script
 // after the non-active finally clauses of all active try conditionals have been
 // executed.  Otherwise, errors and/or interrupts are converted into catchable
-// exceptions, which terminate the script only if not caught.  For user
+// exceptions (did_throw additionally set), which terminate the script only if
-// exceptions, only current_exception is set.  (Note: got_int can be set
+// not caught.  For user exceptions, only did_throw is set.  (Note: got_int can
-// asynchronously afterwards by a SIGINT, so current_exception && got_int is not
+// be set asynchronously afterwards by a SIGINT, so did_throw && got_int is not
 // a reliant test that the exception currently being thrown is an interrupt
 // exception.  Similarly, did_emsg can be set afterwards on an error in an
-// (unskipped) conditional command inside an inactive conditional, so
+// (unskipped) conditional command inside an inactive conditional, so did_throw
-// current_exception && did_emsg is not a reliant test that the exception
+// && did_emsg is not a reliant test that the exception currently being thrown
-// currently being thrown is an error exception.)  -  The macros can be defined
+// is an error exception.)  -  The macros can be defined as expressions checking
-// as expressions checking for a variable that is allowed to be changed during
+// for a variable that is allowed to be changed during execution of a script.
-// execution of a script.
 
 // Values used for the Vim release.
 #define THROW_ON_ERROR true
@@ -71,7 +70,7 @@
 #define CHECK_SKIP \
   (did_emsg \
    || got_int \
-   || current_exception \
+   || did_throw \
    || (cstack->cs_idx > 0 \
        && !(cstack->cs_flags[cstack->cs_idx - 1] & CSF_ACTIVE)))
 
@@ -104,7 +103,7 @@ static int cause_abort = false;
 /// value. "got_int" is also set by calling interrupt().
 int aborting(void)
 {
-  return (did_emsg && force_abort) || got_int || current_exception;
+  return (did_emsg && force_abort) || got_int || did_throw;
 }
 
 /// The value of "force_abort" is temporarily reset by the first emsg() call
@@ -186,7 +185,7 @@ bool cause_errthrow(const char *mesg, bool severe, bool *ignore)
    * currently throwing an exception, do nothing.  The message text will
    * then be stored to v:errmsg by emsg() without displaying it.
    */
-  if (((trylevel == 0 && !cause_abort) || emsg_silent) && !current_exception) {
+  if (((trylevel == 0 && !cause_abort) || emsg_silent) && !did_throw) {
     return false;
   }
 
@@ -217,7 +216,7 @@ bool cause_errthrow(const char *mesg, bool severe, bool *ignore)
    * exception currently being thrown to prevent it from being caught.  Just
    * execute finally clauses and terminate.
    */
-  if (current_exception) {
+  if (did_throw) {
     // When discarding an interrupt exception, reset got_int to prevent the
     // same interrupt being converted to an exception again and discarding
     // the error exception we are about to throw here.
@@ -349,7 +348,7 @@ int do_intthrow(cstack_T *cstack)
 {
   // If no interrupt occurred or no try conditional is active and no exception
   // is being thrown, do nothing (for compatibility of non-EH scripts).
-  if (!got_int || (trylevel == 0 && !current_exception)) {
+  if (!got_int || (trylevel == 0 && !did_throw)) {
     return false;
   }
 
@@ -358,7 +357,7 @@ int do_intthrow(cstack_T *cstack)
     // The interrupt aborts everything except for executing finally clauses.
     // Discard any user or error or interrupt exception currently being
     // thrown.
-    if (current_exception) {
+    if (did_throw) {
       discard_current_exception();
     }
   } else {
@@ -369,7 +368,7 @@ int do_intthrow(cstack_T *cstack)
   // will be terminated then.  -  If an interrupt exception is already
   // being thrown, do nothing.
 
-  if (current_exception) {
+  if (did_throw) {
     if (current_exception->type == ET_INTERRUPT) {
       return false;
     }
@@ -596,6 +595,7 @@ void discard_current_exception(void)
   }
   // Note: all globals manipulated here should be saved/restored in
   // try_enter/try_leave.
+  did_throw = false;
   need_rethrow = false;
 }
 
@@ -1237,6 +1237,8 @@ void do_throw(cstack_T *cstack)
     cstack->cs_flags[idx] &= ~CSF_ACTIVE;
     cstack->cs_exception[idx] = current_exception;
   }
+
+  did_throw = true;
 }
 
 /// Handle ":try"
@@ -1345,7 +1347,7 @@ void ex_catch(exarg_T *eap)
      * corresponding try block never got active (because of an inactive
      * surrounding conditional or after an error or interrupt or throw).
      */
-    if (!current_exception || !(cstack->cs_flags[idx] & CSF_TRUE)) {
+    if (!did_throw || !(cstack->cs_flags[idx] & CSF_TRUE)) {
       skip = true;
     }
 
@@ -1406,10 +1408,10 @@ void ex_catch(exarg_T *eap)
     }
 
     if (caught) {
-      // Make this ":catch" clause active and reset did_emsg and got_int.
+      // Make this ":catch" clause active and reset did_emsg, got_int,
-      // Put the exception on the caught stack.
+      // and did_throw.  Put the exception on the caught stack.
       cstack->cs_flags[idx] |= CSF_ACTIVE | CSF_CAUGHT;
-      did_emsg = got_int = false;
+      did_emsg = got_int = did_throw = false;
       catch_exception((except_T *)cstack->cs_exception[idx]);
       // It's mandatory that the current exception is stored in the cstack
       // so that it can be discarded at the next ":catch", ":finally", or
@@ -1419,10 +1421,6 @@ void ex_catch(exarg_T *eap)
       if (cstack->cs_exception[cstack->cs_idx] != current_exception) {
         internal_error("ex_catch()");
       }
-      // Discarding current_exceptions happens based on what is stored in
-      // cstack->cs_exception, *all* calls to discard_current_exception() are
-      // (and must be) guarded by current_exception check.
-      current_exception = NULL;
     } else {
       /*
        * If there is a preceding catch clause and it caught the exception,
@@ -1477,14 +1475,12 @@ void ex_finally(exarg_T *eap)
     rewind_conditionals(cstack, idx, CSF_WHILE | CSF_FOR,
                         &cstack->cs_looplevel);
 
-    /*
+    // Don't do something when the corresponding try block never got active
-     * Don't do something when the corresponding try block never got active
+    // (because of an inactive surrounding conditional or after an error or
-     * (because of an inactive surrounding conditional or after an error or
+    // interrupt or throw) or for a ":finally" without ":try" or a multiple
-     * interrupt or throw) or for a ":finally" without ":try" or a multiple
+    // ":finally".  After every other error (did_emsg or the conditional
-     * ":finally".  After every other error (did_emsg or the conditional
+    // errors detected above) or after an interrupt (got_int) or an
-     * errors detected above) or after an interrupt (got_int) or an
+    // exception (did_throw), the finally clause must be executed.
-     * exception (current_exception), the finally clause must be executed.
-     */
     skip = !(cstack->cs_flags[cstack->cs_idx] & CSF_TRUE);
 
     if (!skip) {
@@ -1509,22 +1505,20 @@ void ex_finally(exarg_T *eap)
        */
       cleanup_conditionals(cstack, CSF_TRY, false);
 
-      /*
+      // Make did_emsg, got_int, did_throw pending.  If set, they overrule
-       * Make did_emsg, got_int, current_exception pending.  If set, they
+      // a pending ":continue", ":break", ":return", or ":finish".  Then
-       * overrule a pending ":continue", ":break", ":return", or ":finish".
+      // we have particularly to discard a pending return value (as done
-       * Then we have particularly to discard a pending return value (as done
+      // by the call to cleanup_conditionals() above when did_emsg or
-       * by the call to cleanup_conditionals() above when did_emsg or
+      // got_int is set).  The pending values are restored by the
-       * got_int is set).  The pending values are restored by the
+      // ":endtry", except if there is a new error, interrupt, exception,
-       * ":endtry", except if there is a new error, interrupt, exception,
+      // ":continue", ":break", ":return", or ":finish" in the following
-       * ":continue", ":break", ":return", or ":finish" in the following
+      // finally clause.  A missing ":endwhile", ":endfor" or ":endif"
-       * finally clause.  A missing ":endwhile", ":endfor" or ":endif"
+      // detected here is treated as if did_emsg and did_throw had
-       * detected here is treated as if did_emsg and current_exception had
+      // already been set, respectively in case that the error is not
-       * already been set, respectively in case that the error is not
+      // converted to an exception, did_throw had already been unset.
-       * converted to an exception, current_exception had already been unset.
+      // We must not set did_emsg here since that would suppress the
-       * We must not set did_emsg here since that would suppress the
+      // error message.
-       * error message.
+      if (pending == CSTP_ERROR || did_emsg || got_int || did_throw) {
-       */
-      if (pending == CSTP_ERROR || did_emsg || got_int || current_exception) {
         if (cstack->cs_pending[cstack->cs_idx] == CSTP_RETURN) {
           report_discard_pending(CSTP_RETURN,
                                  cstack->cs_rettv[cstack->cs_idx]);
@@ -1533,7 +1527,7 @@ void ex_finally(exarg_T *eap)
         if (pending == CSTP_ERROR && !did_emsg) {
           pending |= (THROW_ON_ERROR ? CSTP_THROW : 0);
         } else {
-          pending |= (current_exception ? CSTP_THROW : 0);
+          pending |= (did_throw ? CSTP_THROW : 0);
         }
         pending |= did_emsg  ? CSTP_ERROR     : 0;
         pending |= got_int   ? CSTP_INTERRUPT : 0;
@@ -1547,19 +1541,16 @@ void ex_finally(exarg_T *eap)
         // exception.  When emsg() is called for a missing ":endif" or
         // a missing ":endwhile"/":endfor" detected here, the
         // exception will be discarded.
-        if (current_exception
+        if (did_throw && cstack->cs_exception[cstack->cs_idx] != current_exception) {
-            && cstack->cs_exception[cstack->cs_idx] != current_exception) {
           internal_error("ex_finally()");
         }
       }
 
-      /*
+      // Set CSL_HAD_FINA, so do_cmdline() will reset did_emsg,
-       * Set CSL_HAD_FINA, so do_cmdline() will reset did_emsg,
+      // got_int, and did_throw and make the finally clause active.
-       * got_int, and current_exception and make the finally clause active.
+      // This will happen after emsg() has been called for a missing
-       * This will happen after emsg() has been called for a missing
+      // ":endif" or a missing ":endwhile"/":endfor" detected here, so
-       * ":endif" or a missing ":endwhile"/":endfor" detected here, so
+      // that the following finally clause will be executed even then.
-       * that the following finally clause will be executed even then.
-       */
       cstack->cs_lflags |= CSL_HAD_FINA;
     }
   }
@@ -1587,8 +1578,7 @@ void ex_endtry(exarg_T *eap)
     // made inactive by a ":continue", ":break", ":return", or ":finish" in
     // the finally clause.  The latter case need not be tested since then
     // anything pending has already been discarded.
-    bool skip = did_emsg || got_int || current_exception
+    bool skip = did_emsg || got_int || did_throw || !(cstack->cs_flags[cstack->cs_idx] & CSF_TRUE);
-                || !(cstack->cs_flags[cstack->cs_idx] & CSF_TRUE);
 
     if (!(cstack->cs_flags[cstack->cs_idx] & CSF_TRY)) {
       eap->errmsg = get_end_emsg(cstack);
@@ -1602,14 +1592,12 @@ void ex_endtry(exarg_T *eap)
                           &cstack->cs_looplevel);
       skip = true;
 
-      /*
+      // If an exception is being thrown, discard it to prevent it from
-       * If an exception is being thrown, discard it to prevent it from
+      // being rethrown at the end of this function.  It would be
-       * being rethrown at the end of this function.  It would be
+      // discarded by the error message, anyway.  Resets did_throw.
-       * discarded by the error message, anyway.  Resets current_exception.
+      // This does not affect the script termination due to the error
-       * This does not affect the script termination due to the error
+      // since "trylevel" is decremented after emsg() has been called.
-       * since "trylevel" is decremented after emsg() has been called.
+      if (did_throw) {
-       */
-      if (current_exception) {
         discard_current_exception();
       }
 
@@ -1624,7 +1612,7 @@ void ex_endtry(exarg_T *eap)
        * a finally clause, we need to rethrow it after closing the try
        * conditional.
        */
-      if (current_exception
+      if (did_throw
           && (cstack->cs_flags[idx] & CSF_TRUE)
           && !(cstack->cs_flags[idx] & CSF_FINALLY)) {
         rethrow = true;
@@ -1648,10 +1636,10 @@ void ex_endtry(exarg_T *eap)
       if (got_int) {
         skip = true;
         (void)do_intthrow(cstack);
-        // The do_intthrow() call may have reset current_exception or
+        // The do_intthrow() call may have reset did_throw or
         // cstack->cs_pending[idx].
         rethrow = false;
-        if (current_exception && !(cstack->cs_flags[idx] & CSF_FINALLY)) {
+        if (did_throw && !(cstack->cs_flags[idx] & CSF_FINALLY)) {
           rethrow = true;
         }
       }
@@ -1721,7 +1709,7 @@ void ex_endtry(exarg_T *eap)
       // When the finally clause was entered due to an error,
       // interrupt or throw (as opposed to a ":continue", ":break",
       // ":return", or ":finish"), restore the pending values of
-      // did_emsg, got_int, and current_exception.  This is skipped, if there
+      // did_emsg, got_int, and did_throw.  This is skipped, if there
       // was a new error, interrupt, throw, ":continue", ":break",
       // ":return", or ":finish".  in the finally clause.
       default:
@@ -1768,24 +1756,22 @@ void enter_cleanup(cleanup_T *csp)
 {
   int pending = CSTP_NONE;
 
-  /*
+  // Postpone did_emsg, got_int, did_throw.  The pending values will be
-   * Postpone did_emsg, got_int, current_exception.  The pending values will be
+  // restored by leave_cleanup() except if there was an aborting error,
-   * restored by leave_cleanup() except if there was an aborting error,
+  // interrupt, or uncaught exception after this function ends.
-   * interrupt, or uncaught exception after this function ends.
+  if (did_emsg || got_int || did_throw || need_rethrow) {
-   */
-  if (did_emsg || got_int || current_exception || need_rethrow) {
     csp->pending = (did_emsg ? CSTP_ERROR : 0)
                    | (got_int ? CSTP_INTERRUPT : 0)
-                   | (current_exception ? CSTP_THROW : 0)
+                   | (did_throw ? CSTP_THROW : 0)
                    | (need_rethrow ? CSTP_THROW : 0);
 
-    // If we are currently throwing an exception, save it as well.  On an error
+    // If we are currently throwing an exception (did_throw), save it as
-    // not yet converted to an exception, update "force_abort" and reset
+    // well.  On an error not yet converted to an exception, update
-    // "cause_abort" (as do_errthrow() would do).  This is needed for the
+    // "force_abort" and reset "cause_abort" (as do_errthrow() would do).
-    // do_cmdline() call that is going to be made for autocommand execution.  We
+    // This is needed for the do_cmdline() call that is going to be made
-    // need not save *msg_list because there is an extra instance for every call
+    // for autocommand execution.  We need not save *msg_list because
-    // of do_cmdline(), anyway.
+    // there is an extra instance for every call of do_cmdline(), anyway.
-    if (current_exception || need_rethrow) {
+    if (did_throw || need_rethrow) {
       csp->exception = current_exception;
       current_exception = NULL;
     } else {
@@ -1795,8 +1781,7 @@ void enter_cleanup(cleanup_T *csp)
         cause_abort = false;
       }
     }
-    did_emsg = got_int = need_rethrow = false;
+    did_emsg = got_int = did_throw = need_rethrow = false;
-    current_exception = NULL;
 
     // Report if required by the 'verbose' option or when debugging.
     report_make_pending(pending, csp->exception);
@@ -1866,7 +1851,7 @@ void leave_cleanup(cleanup_T *csp)
       force_abort = false;
     }
 
-    // Restore the pending values of did_emsg, got_int, and current_exception.
+    // Restore the pending values of did_emsg, got_int, and did_throw.
     if (pending & CSTP_ERROR) {
       did_emsg = true;
     }
@@ -1874,7 +1859,7 @@ void leave_cleanup(cleanup_T *csp)
       got_int = true;
     }
     if (pending & CSTP_THROW) {
-      need_rethrow = true;  // current_exception will be set by do_one_cmd()
+      need_rethrow = true;  // did_throw will be set by do_one_cmd()
     }
 
     // Report if required by the 'verbose' option or when debugging.

src/nvim/globals.h

@@ -241,9 +241,13 @@ EXTERN int do_profiling INIT(= PROF_NONE);      ///< PROF_ values
 
 /// Exception currently being thrown.  Used to pass an exception to a different
 /// cstack.  Also used for discarding an exception before it is caught or made
-/// pending.
+/// pending.  Only valid when did_throw is true.
 EXTERN except_T *current_exception;
 
+/// An exception is being thrown.  Reset when the exception is caught or as
+/// long as it is pending in a finally clause.
+EXTERN bool did_throw INIT(= false);
+
 /// Set when a throw that cannot be handled in do_cmdline() must be propagated
 /// to the cstack of the previously called do_cmdline().
 EXTERN bool need_rethrow INIT(= false);

src/nvim/lua/executor.c

@@ -1027,7 +1027,7 @@ int nlua_call(lua_State *lstate)
     // TODO(bfredl): this should be simplified in error handling refactor
     force_abort = false;
     suppress_errthrow = false;
-    current_exception = NULL;
+    did_throw = false;
     did_emsg = false;
 
     try_start();

test/functional/plugin/man_spec.lua

@@ -6,6 +6,12 @@ local funcs = helpers.funcs
 local nvim_prog = helpers.nvim_prog
 local matches = helpers.matches
 
+clear()
+if funcs.executable('man') == 0 then
+  pending('missing "man" command', function() end)
+  return
+end
+
 describe(':Man', function()
   before_each(function()
     clear()

test/functional/vimscript/eval_spec.lua

@@ -219,3 +219,31 @@ it('Error when if/for/while/try/function is nested too deep',function()
   feed(':call Test5()<CR>')
   screen:expect({any = 'E1058: '})
 end)
+
+describe("uncaught exception", function()
+  before_each(clear)
+  after_each(function()
+    os.remove('throw1.vim')
+    os.remove('throw2.vim')
+    os.remove('throw3.vim')
+  end)
+
+  it('is not forgotten #13490', function()
+    command('autocmd BufWinEnter * throw "i am error"')
+    eq('i am error', exc_exec('try | new | endtry'))
+
+    -- Like Vim, throwing here aborts the processing of the script, but does not stop :runtime!
+    -- from processing the others.
+    -- Only the first thrown exception should be rethrown from the :try below, though.
+    for i = 1, 3 do
+      write_file('throw' .. i .. '.vim', ([[
+        let result ..= '%d'
+        throw 'throw%d'
+        let result ..= 'X'
+      ]]):format(i, i))
+    end
+    command('set runtimepath+=. | let result = ""')
+    eq('throw1', exc_exec('try | runtime! throw*.vim | endtry'))
+    eq('123', eval('result'))
+  end)
+end)