script_nullpo_end: Change error printf fmt -> arg

PR !270 is an ongoing investigation into outstanding compiler warnings.

One such warning is `warning: format '%s' expects a matching 'char*' argument`
from `script_nullpo_end(nd, STRPRINTF("no such npc: '%s'"_fmt, name));` in
`src/map/script-fun.cpp`. No such warning is emitted from a similar line in
`src/map/atcommand.cpp`: `AString output = STRPRINTF("Jump to %s"_fmt, npc);`.

`script_nullpo_end` is a macro, rather than a function. `error` is passed in
verbatim by the preprocessor. The macro definition of `script_nullpo_end`
includes lines such as the following:

```cpp
PRINTF("script:%s: " #error " @ %s\n"_fmt, BUILTIN_NAME(), nullpo_nd->name);
```

`#<variable>`  instructs the preprocessor to transform `<variable>` into a
literal string. In this case, the string literal:

```cpp
"STRPRINTF(\"no such npc: '%s'\"_fmt, name)"
```

So the entire line partly resolves to something like:

```cpp
printf("script:%s: STRPRINTF(\"no such npc: '%s'\"_fmt, name) @ %s\n"_fmt, BUILTIN_NAME(), nullpo_nd->name);
```

Once the compiler sees this, it throws out the warning seen here, because
printf is seeing three placeholders in the formatter, but is only given two
value arguments.


Checking with `gcc -E`, the full expansion is as follows:

```cpp
    if (nullpo_chk("script-fun.cpp", 4885, __PRETTY_FUNCTION__, nd)) { if (st->oid) { dumb_ptr<npc_data> nullpo_nd = map_id_is_npc(st->oid); if (nullpo_nd && nullpo_nd->name) { ({ struct format_impl { constexpr static FormatString print_format() __asm__("_print_format") { return "script:%s: " "STRPRINTF(\"no such npc: '%s'\"_fmt, npc)" " @ %s\n"_fmt; } }; cxxstdio::PrintFormatter<format_impl>::print((
# 4885 "script-fun.cpp" 3 4
   stdout
# 4885 "script-fun.cpp"
   ), (builtin_functions[st->stack->stack_datav[st->start].get_if<ScriptDataFuncRef>()->numi].name), nullpo_nd->name); }); } else if (nullpo_nd) { ({ struct format_impl { constexpr static FormatString print_format() __asm__("_print_format") { return "script:%s: " "STRPRINTF(\"no such npc: '%s'\"_fmt, npc)" " (unnamed npc)\n"_fmt; } }; cxxstdio::PrintFormatter<format_impl>::print((
# 4885 "script-fun.cpp" 3 4
   stdout
# 4885 "script-fun.cpp"
   ), (builtin_functions[st->stack->stack_datav[st->start].get_if<ScriptDataFuncRef>()->numi].name)); }); } else { ({ struct format_impl { constexpr static FormatString print_format() __asm__("_print_format") { return "script:%s: " "STRPRINTF(\"no such npc: '%s'\"_fmt, npc)" " (no npc)\n"_fmt; } }; cxxstdio::PrintFormatter<format_impl>::print((
# 4885 "script-fun.cpp" 3 4
   stdout
# 4885 "script-fun.cpp"
   ), (builtin_functions[st->stack->stack_datav[st->start].get_if<ScriptDataFuncRef>()->numi].name)); }); } } else { ({ struct format_impl { constexpr static FormatString print_format() __asm__("_print_format") { return "script:%s: " "STRPRINTF(\"no such npc: '%s'\"_fmt, npc)" " (no npc)\n"_fmt; } }; cxxstdio::PrintFormatter<format_impl>::print((
# 4885 "script-fun.cpp" 3 4
   stdout
# 4885 "script-fun.cpp"
   ), (builtin_functions[st->stack->stack_datav[st->start].get_if<ScriptDataFuncRef>()->numi].name)); }); } st->state = ScriptEndState::END; return; };
```

Note the  string literal: `"STRPRINTF(\"no such npc: '%s'\"_fmt, npc)"`.
`script_nullpo_end` currently can't take as its argument for `error` any
expression which, when stringified, contains something which `printf` will
interpret as its formatter expecting another argument.

This appears to have been broken since it was first introduced in
https://git.themanaworld.org/legacy/tmwa/-/commit/594eafd4f231a897cbefd
since the first revision implicitly had these requirements, and also
introduced usage which didn't meet them.

This rewrites each PRINTF line in `script_nullpo_end` from the template

```cpp
PRINTF("script:%s: " #error " @ %s\n"_fmt, BUILTIN_NAME(), nullpo_nd->name);
```
to something like
```cpp
PRINTF("script:%s: %s @ %s\n"_fmt, BUILTIN_NAME(), error, nullpo_nd->name);
```

This means that instead of an expression being stringified, error is
interpreted as an expression that resolves (or decays) to a string.

This seems consistent with all current usage of `script_nullpo_end`.

1 files changed, 4 insertions, 4 deletions

diff --git a/src/map/script-fun.cpp b/src/map/script-fun.cpp
index 2be0333..deb781a 100644
--- a/src/map/script-fun.cpp
+++ b/src/map/script-fun.cpp
@@ -80,14 +80,14 @@ namespace map
         if (st->oid) {                                                                          \
             dumb_ptr<npc_data> nullpo_nd = map_id_is_npc(st->oid);                              \
             if (nullpo_nd && nullpo_nd->name) {                                                 \
-                PRINTF("script:%s: " #error " @ %s\n"_fmt, BUILTIN_NAME(), nullpo_nd->name);    \
+                PRINTF("script:%s: %s @ %s\n"_fmt, BUILTIN_NAME(), error, nullpo_nd->name);     \
             } else if (nullpo_nd) {                                                             \
-                PRINTF("script:%s: " #error " (unnamed npc)\n"_fmt, BUILTIN_NAME());            \
+                PRINTF("script:%s: %s (unnamed npc)\n"_fmt, BUILTIN_NAME(), error);             \
             } else {                                                                            \
-                PRINTF("script:%s: " #error " (no npc)\n"_fmt, BUILTIN_NAME());                 \
+                PRINTF("script:%s: %s (no npc)\n"_fmt, BUILTIN_NAME(), error);                  \
             }                                                                                   \
         } else {                                                                                \
-            PRINTF("script:%s: " #error " (no npc)\n"_fmt, BUILTIN_NAME());                     \
+            PRINTF("script:%s: %s (no npc)\n"_fmt, BUILTIN_NAME(), error);                      \
         }                                                                                       \
         st->state = ScriptEndState::END;                                                        \
         return;                                                                                 \