fix: make_filter_cmd for :! powershell

Problem:
`Start-Process` requires the command to be split into the shell
command and its arguments. Previously it was done by parsing, which
didn't handle cases such as
  - commands with escaped space in their filepath
  - quoted commands with space in their filepath

Solution:
Use
  - `pwsh -Command` instead of `Start-Process`
  - `Get-Content` instead of `-RedirectStandardInput`
  - `Out-File` instead of `-RedirectStandardOutput`

4 files changed, 46 insertions, 59 deletions

diff --git a/runtime/doc/options.txt b/runtime/doc/options.txt
index 836272a60f..5871b82d9c 100644
--- a/runtime/doc/options.txt
+++ b/runtime/doc/options.txt
@@ -5357,7 +5357,7 @@ A jump table for the options with a short description can be found at |Q_op|.
 	To use PowerShell: >
 		let &shell = executable('pwsh') ? 'pwsh' : 'powershell'
 		let &shellcmdflag = '-NoLogo -NoProfile -ExecutionPolicy RemoteSigned -Command [Console]::InputEncoding=[Console]::OutputEncoding=[System.Text.Encoding]::UTF8;'
-		let &shellredir = '-RedirectStandardOutput %s -NoNewWindow -Wait'
+		let &shellredir = '2>&1 | Out-File -Encoding UTF8 %s; exit $LastExitCode'
 		let &shellpipe = '2>&1 | Out-File -Encoding UTF8 %s; exit $LastExitCode'
 		set shellquote= shellxquote=
 
diff --git a/src/nvim/ex_cmds.c b/src/nvim/ex_cmds.c
index 462212c4ce..a6a4f52323 100644
--- a/src/nvim/ex_cmds.c
+++ b/src/nvim/ex_cmds.c
@@ -1544,84 +1544,71 @@ char *make_filter_cmd(char *cmd, char *itmp, char *otmp)
 
   size_t len = strlen(cmd) + 1;  // At least enough space for cmd + NULL.
 
-  len += is_fish_shell ?  sizeof("begin; " "; end") - 1
-                       :  is_pwsh ? sizeof("Start-Process ")
-                                  : sizeof("(" ")") - 1;
+  len += is_fish_shell ? sizeof("begin; " "; end") - 1
+                       : !is_pwsh ? sizeof("(" ")") - 1
+                                  : 0;
 
   if (itmp != NULL) {
-    len += is_pwsh  ? strlen(itmp) + sizeof(" -RedirectStandardInput ")
+    len += is_pwsh  ? strlen(itmp) + sizeof("Get-Content " " | & ") - 1
                     : strlen(itmp) + sizeof(" { " " < " " } ") - 1;
   }
   if (otmp != NULL) {
     len += strlen(otmp) + strlen(p_srr) + 2;  // two extra spaces ("  "),
   }
 
-  const char *const cmd_args = strchr(cmd, ' ');
-  len += (is_pwsh && cmd_args)
-      ? strlen(" -ArgumentList ") + 2  // two extra quotes
-      : 0;
-
   char *const buf = xmalloc(len);
 
   if (is_pwsh) {
-    xstrlcpy(buf, "Start-Process ", len);
-    if (cmd_args == NULL) {
-      xstrlcat(buf, cmd, len);
+    if (itmp != NULL) {
+      xstrlcpy(buf, "Get-Content ", len - 1);  // FIXME: should we add "-Encoding utf8"?
+      xstrlcat(buf, (const char *)itmp, len - 1);
+      xstrlcat(buf, " | & ", len - 1);  // FIXME: add `&` ourself or leave to user?
+      xstrlcat(buf, cmd, len - 1);
     } else {
-      xstrlcpy(buf + strlen(buf), cmd, (size_t)(cmd_args - cmd + 1));
-      xstrlcat(buf, " -ArgumentList \"", len);
-      xstrlcat(buf, cmd_args + 1, len);  // +1 to skip the leading space.
-      xstrlcat(buf, "\"", len);
+      xstrlcpy(buf, cmd, len - 1);
     }
+  } else {
 #if defined(UNIX)
     // Put delimiters around the command (for concatenated commands) when
     // redirecting input and/or output.
-  } else if (itmp != NULL || otmp != NULL) {
-    char *fmt = is_fish_shell ? "begin; %s; end"
-                              :       "(%s)";
-    vim_snprintf(buf, len, fmt, cmd);
-#endif
-    // For shells that don't understand braces around commands, at least allow
-    // the use of commands in a pipe.
-  } else {
-    xstrlcpy(buf, cmd, len);
-  }
-
-#if defined(UNIX)
-  if (itmp != NULL) {
-    if (is_pwsh) {
-      xstrlcat(buf, " -RedirectStandardInput ", len - 1);
+    if (itmp != NULL || otmp != NULL) {
+      char *fmt = is_fish_shell ? "begin; %s; end"
+        :       "(%s)";
+      vim_snprintf(buf, len, fmt, cmd);
     } else {
+      xstrlcpy(buf, cmd, len);
+    }
+
+    if (itmp != NULL) {
       xstrlcat(buf, " < ", len - 1);
+      xstrlcat(buf, (const char *)itmp, len - 1);
     }
-    xstrlcat(buf, itmp, len - 1);
-  }
 #else
-  if (itmp != NULL) {
-    // If there is a pipe, we have to put the '<' in front of it.
-    // Don't do this when 'shellquote' is not empty, otherwise the
-    // redirection would be inside the quotes.
-    if (*p_shq == NUL) {
-      char *const p = find_pipe(buf);
-      if (p != NULL) {
-        *p = NUL;
+    // For shells that don't understand braces around commands, at least allow
+    // the use of commands in a pipe.
+    xstrlcpy(buf, (char *)cmd, len);
+    if (itmp != NULL) {
+      // If there is a pipe, we have to put the '<' in front of it.
+      // Don't do this when 'shellquote' is not empty, otherwise the
+      // redirection would be inside the quotes.
+      if (*p_shq == NUL) {
+        char *const p = find_pipe(buf);
+        if (p != NULL) {
+          *p = NUL;
+        }
       }
-    }
-    if (is_pwsh) {
-      xstrlcat(buf, " -RedirectStandardInput ", len);
-    } else {
       xstrlcat(buf, " < ", len);
-    }
-    xstrlcat(buf, itmp, len);
-    if (*p_shq == NUL) {
-      const char *const p = find_pipe(cmd);
-      if (p != NULL) {
-        xstrlcat(buf, " ", len - 1);  // Insert a space before the '|' for DOS
-        xstrlcat(buf, p, len - 1);
+      xstrlcat(buf, (const char *)itmp, len);
+      if (*p_shq == NUL) {
+        const char *const p = find_pipe((const char *)cmd);
+        if (p != NULL) {
+          xstrlcat(buf, " ", len - 1);  // Insert a space before the '|' for DOS
+          xstrlcat(buf, p, len - 1);
+        }
       }
     }
-  }
 #endif
+  }
   if (otmp != NULL) {
     append_redir(buf, len, p_srr, otmp);
   }
diff --git a/test/functional/helpers.lua b/test/functional/helpers.lua
index 3aec834bea..4fcc190dee 100644
--- a/test/functional/helpers.lua
+++ b/test/functional/helpers.lua
@@ -562,16 +562,16 @@ function module.set_shell_powershell(fake)
     assert(found)
   end
   local shell = found and (iswin() and 'powershell' or 'pwsh') or module.testprg('pwsh-test')
-  local set_encoding = '[Console]::InputEncoding=[Console]::OutputEncoding=[System.Text.Encoding]::UTF8;'
+  local set_encoding = '[Console]::InputEncoding=[Console]::OutputEncoding=[System.Text.UTF8Encoding]::new();'
   local cmd = set_encoding..'Remove-Item -Force '..table.concat(iswin()
-    and {'alias:cat', 'alias:echo', 'alias:sleep'}
+    and {'alias:cat', 'alias:echo', 'alias:sleep', 'alias:sort'}
     or  {'alias:echo'}, ',')..';'
   module.exec([[
     let &shell = ']]..shell..[['
     set shellquote= shellxquote=
     let &shellcmdflag = '-NoLogo -NoProfile -ExecutionPolicy RemoteSigned -Command ]]..cmd..[['
     let &shellpipe = '2>&1 | Out-File -Encoding UTF8 %s; exit $LastExitCode'
-    let &shellredir = '-RedirectStandardOutput %s -NoNewWindow -Wait'
+    let &shellredir = '2>&1 | Out-File -Encoding UTF8 %s; exit $LastExitCode'
   ]])
   return found
 end
diff --git a/test/functional/vimscript/system_spec.lua b/test/functional/vimscript/system_spec.lua
index a778e2f435..d0061d051e 100644
--- a/test/functional/vimscript/system_spec.lua
+++ b/test/functional/vimscript/system_spec.lua
@@ -642,12 +642,12 @@ describe('shell :!', function()
     if iswin() then
       feed(':4verbose %!sort /R<cr>')
       screen:expect{
-        any=[[Executing command: .?Start%-Process sort %-ArgumentList "/R" %-RedirectStandardInput .* %-RedirectStandardOutput .* %-NoNewWindow %-Wait]]
+        any=[[Executing command: .?Get%-Content .* | & sort /R 2>&1 | Out%-File %-Encoding UTF8 .*; exit $LastExitCode]]
       }
     else
       feed(':4verbose %!sort -r<cr>')
       screen:expect{
-        any=[[Executing command: .?Start%-Process sort %-ArgumentList "%-r" %-RedirectStandardInput .* %-RedirectStandardOutput .* %-NoNewWindow %-Wait]]
+        any=[[Executing command: .?Get%-Content .* | & sort %-r 2>&1 | Out%-File %-Encoding UTF8 .*; exit $LastExitCode]]
       }
     end
     feed('<CR>')