Revert "Add GUC backtrace_on_internal_error"

This reverts commit a740b213d4.

Subsequent discussion showed that there was interest in a more general
facility to configure when server log events would produce backtraces,
and this existing limited way couldn't be extended in a compatible
way.  So the consensus was to revert this for PostgreSQL 17 and
reconsider this topic for PostgreSQL 18.

Discussion: https://www.postgresql.org/message-id/flat/CAGECzQTChkvn5Xj772LB3%3Dxo2x_LcaO5O0HQvXqobm1xVp6%2B4w%40mail.gmail.com#764bcdbb73e162787e1ad984935e51e3

doc/src/sgml/config.sgml

@@ -11381,33 +11381,6 @@ dynamic_library_path = 'C:\tools\postgresql;H:\my_project\lib;$libdir'
       </listitem>
      </varlistentry>
 
-     <varlistentry id="guc-backtrace-on-internal-error" xreflabel="backtrace_on_internal_error">
-      <term><varname>backtrace_on_internal_error</varname> (<type>boolean</type>)
-      <indexterm>
-        <primary><varname>backtrace_on_internal_error</varname> configuration parameter</primary>
-      </indexterm>
-      </term>
-      <listitem>
-       <para>
-        If this parameter is on and an error with error code XX000 (internal
-        error; see also <xref linkend="errcodes-appendix"/>) is raised, then a
-        backtrace is written to the server log together with the error
-        message.  This can be used to debug such internal errors (which should
-        normally not happen in production).  The default is off.
-       </para>
-
-       <para>
-        Backtrace support is not available on all platforms, and the quality
-        of the backtraces depends on compilation options.
-       </para>
-
-       <para>
-        Only superusers and users with the appropriate <literal>SET</literal>
-        privilege can change this setting.
-       </para>
-      </listitem>
-     </varlistentry>
-
      <varlistentry id="guc-debug-discard-caches" xreflabel="debug_discard_caches">
       <term><varname>debug_discard_caches</varname> (<type>integer</type>)
       <indexterm>

src/backend/utils/error/elog.c

@@ -497,11 +497,9 @@ errfinish(const char *filename, int lineno, const char *funcname)
 
 	/* Collect backtrace, if enabled and we didn't already */
 	if (!edata->backtrace &&
-		((edata->funcname &&
-		  backtrace_functions &&
-		  matches_backtrace_functions(edata->funcname)) ||
-		 (edata->sqlerrcode == ERRCODE_INTERNAL_ERROR &&
-		  backtrace_on_internal_error)))
+		edata->funcname &&
+		backtrace_functions &&
+		matches_backtrace_functions(edata->funcname))
 		set_backtrace(edata, 2);
 
 	/*

src/backend/utils/misc/guc_tables.c

@@ -531,7 +531,6 @@ int			log_temp_files = -1;
 double		log_statement_sample_rate = 1.0;
 double		log_xact_sample_rate = 0;
 char	   *backtrace_functions;
-bool		backtrace_on_internal_error = false;
 
 int			temp_file_limit = -1;
 
@@ -770,16 +769,6 @@ StaticAssertDecl(lengthof(config_type_names) == (PGC_ENUM + 1),
 
 struct config_bool ConfigureNamesBool[] =
 {
-	{
-		{"backtrace_on_internal_error", PGC_SUSET, DEVELOPER_OPTIONS,
-			gettext_noop("Log backtrace for any error with error code XX000 (internal error)."),
-			NULL,
-			GUC_NOT_IN_SAMPLE
-		},
-		&backtrace_on_internal_error,
-		false,
-		NULL, NULL, NULL
-	},
 	{
 		{"enable_seqscan", PGC_USERSET, QUERY_TUNING_METHOD,
 			gettext_noop("Enables the planner's use of sequential-scan plans."),

src/include/utils/guc.h

@@ -267,7 +267,6 @@ extern PGDLLIMPORT int log_temp_files;
 extern PGDLLIMPORT double log_statement_sample_rate;
 extern PGDLLIMPORT double log_xact_sample_rate;
 extern PGDLLIMPORT char *backtrace_functions;
-extern PGDLLIMPORT bool backtrace_on_internal_error;
 
 extern PGDLLIMPORT int temp_file_limit;