Luogu customized GCC diff. https://www.luogu.com.cn/discuss/show/259685

no-pragma-attribs-optimize-and-target.diff

--- a/src/gcc/c-family/c-attribs.c
+++ b/src/gcc/c-family/c-attribs.c
@@ -4894,6 +4894,11 @@
 handle_optimize_attribute (tree *node, tree name, tree args,
 			   int ARG_UNUSED (flags), bool *no_add_attrs)
 {
+  if (getenv("ONLINE_JUDGE"))
+    {
+      error_at (DECL_SOURCE_LOCATION (*node), "%qE attribute is disallowed in online judge mode", name);
+      return NULL_TREE;
+    }
   /* Ensure we have a function type.  */
   if (TREE_CODE (*node) != FUNCTION_DECL)
     {

--- a/src/gcc/c-family/c-pragma.c
+++ b/src/gcc/c-family/c-pragma.c
@@ -862,6 +862,11 @@
   tree x;
   bool close_paren_needed_p = false;
 
+  if (getenv("ONLINE_JUDGE"))
+    {
+      error ("%<#pragma GCC option%> is not allowed in online judge mode");
+      return;
+    }
   if (cfun)
     {
       error ("%<#pragma GCC option%> is not allowed inside functions");
@@ -931,6 +936,11 @@
   bool close_paren_needed_p = false;
   tree optimization_previous_node = optimization_current_node;
 
+  if (getenv("ONLINE_JUDGE"))
+    {
+      error ("%<#pragma GCC optimize%> is not allowed in online judge mode");
+      return;
+    }
   if (cfun)
     {
       error ("%<#pragma GCC optimize%> is not allowed inside functions");

no-pragma-attribs-optimize.diff

--- a/src/gcc/c-family/c-attribs.c
+++ b/src/gcc/c-family/c-attribs.c
@@ -4894,6 +4894,11 @@
 handle_optimize_attribute (tree *node, tree name, tree args,
 			   int ARG_UNUSED (flags), bool *no_add_attrs)
 {
+  if (getenv("ONLINE_JUDGE"))
+    {
+      error_at (DECL_SOURCE_LOCATION (*node), "%qE attribute is disallowed in online judge mode", name);
+      return NULL_TREE;
+    }
   /* Ensure we have a function type.  */
   if (TREE_CODE (*node) != FUNCTION_DECL)
     {

--- a/src/gcc/c-family/c-pragma.c
+++ b/src/gcc/c-family/c-pragma.c
@@ -931,6 +936,11 @@
   bool close_paren_needed_p = false;
   tree optimization_previous_node = optimization_current_node;
 
+  if (getenv("ONLINE_JUDGE"))
+    {
+      error ("%<#pragma GCC optimize%> is not allowed in online judge mode");
+      return;
+    }
   if (cfun)
     {
       error ("%<#pragma GCC optimize%> is not allowed inside functions");

no-pragma-target.diff

--- a/src/gcc/c-family/c-pragma.c
+++ b/src/gcc/c-family/c-pragma.c
@@ -862,6 +862,11 @@
   tree x;
   bool close_paren_needed_p = false;
 
+  if (getenv("ONLINE_JUDGE"))
+    {
+      error ("%<#pragma GCC option%> is not allowed in online judge mode");
+      return;
+    }
   if (cfun)
     {
       error ("%<#pragma GCC option%> is not allowed inside functions");