MDEV-33019 The database part is not case sensitive in SP names

Part#1 A non-functional change

Changing the signature of Identifier_chain2::make_qname() from

  bool make_qname(MEM_ROOT *mem_root, LEX_CSTRING *dst) const;

to

  LEX_CSTRING make_qname(MEM_ROOT *mem_root) const;

Now the result is returned as LEX_CSTRING from the function rather than
is passed as a parameter.
The return value {NULL,0} means "EOM".

sql/sql_class.h

@@ -7088,20 +7088,21 @@ class Identifier_chain2
   }
 
   // Export as a qualified name string, allocate on mem_root.
-  bool make_qname(MEM_ROOT *mem_root, LEX_CSTRING *dst) const
+  LEX_CSTRING make_qname(MEM_ROOT *mem_root) const
   {
-    const uint dot= !!m_name[0].length;
-    char *tmp;
+    LEX_STRING dst;
     /* format: [pkg + dot] + name + '\0' */
-    dst->length= m_name[0].length + dot + m_name[1].length;
-    if (unlikely(!(dst->str= tmp= (char*) alloc_root(mem_root,
-                                                     dst->length + 1))))
-      return true;
-    snprintf(tmp, dst->length + 1, "%.*s%.*s%.*s",
-            (int) m_name[0].length, (m_name[0].length ? m_name[0].str : ""),
-            dot, ".",
-            (int) m_name[1].length, m_name[1].str);
-    return false;
+    size_t dst_size= m_name[0].length + 1 /*dot*/ + m_name[1].length + 1/*\0*/;
+    if (unlikely(!(dst.str= (char*) alloc_root(mem_root, dst_size))))
+      return {NULL, 0};
+    if (!m_name[0].length)
+    {
+      dst.length= my_snprintf(dst.str, dst_size, "%.*s",
+                              (int) m_name[1].length, m_name[1].str);
+      return {dst.str, dst.length};
+    }
+    dst.length= make_qname(dst.str, dst_size);
+    return {dst.str, dst.length};
   }
 };
 
@@ -7154,10 +7155,10 @@ class Database_qualified_name
     return Identifier_chain2(m_db, m_name).make_qname(dst, dstlen);
   }
   // Export db and name as a qualified name string, allocate on mem_root.
-  bool make_qname(MEM_ROOT *mem_root, LEX_CSTRING *dst) const
+  LEX_CSTRING make_qname(MEM_ROOT *mem_root) const
   {
     DBUG_SLOW_ASSERT(ok_for_lower_case_names(m_db.str));
-    return Identifier_chain2(m_db, m_name).make_qname(mem_root, dst);
+    return Identifier_chain2(m_db, m_name).make_qname(mem_root);
   }
 
   bool make_package_routine_name(MEM_ROOT *mem_root,

sql/sql_lex.cc

@@ -6754,7 +6754,8 @@ sp_head *LEX::make_sp_head(THD *thd, const sp_name *name,
                                       name->m_name);
       else
         sp->init_sp_name(name);
-      sp->make_qname(sp->get_main_mem_root(), &sp->m_qname);
+      if (!(sp->m_qname= sp->make_qname(sp->get_main_mem_root())).str)
+        return NULL;
     }
     sphead= sp;
   }
@@ -8632,7 +8633,7 @@ bool LEX::call_statement_start(THD *thd, const LEX_CSTRING &db,
 
   // Concat `pkg` and `name` to `pkg.name`
   LEX_CSTRING pkg_dot_proc;
-  if (q_pkg_proc.make_qname(thd->mem_root, &pkg_dot_proc) ||
+  if (!(pkg_dot_proc= q_pkg_proc.make_qname(thd->mem_root)).str ||
       check_ident_length(&pkg_dot_proc) ||
       !(spname= new (thd->mem_root) sp_name(&db, &pkg_dot_proc, true)))
     return true;
@@ -8698,7 +8699,8 @@ sp_package *LEX::create_package_start(THD *thd,
     return NULL;
   pkg->reset_thd_mem_root(thd);
   pkg->init(this);
-  pkg->make_qname(pkg->get_main_mem_root(), &pkg->m_qname);
+  if (!(pkg->m_qname= pkg->make_qname(pkg->get_main_mem_root())).str)
+    return NULL;
   sphead= pkg;
   return pkg;
 }
@@ -9043,7 +9045,7 @@ Item *LEX::make_item_func_call_generic(THD *thd,
 
   // Concat `pkg` and `name` to `pkg.name`
   LEX_CSTRING pkg_dot_func;
-  if (q_pkg_func.make_qname(thd->mem_root, &pkg_dot_func) ||
+  if (!(pkg_dot_func= q_pkg_func.make_qname(thd->mem_root)).str ||
       check_ident_length(&pkg_dot_func) ||
       !(qname= new (thd->mem_root) sp_name(&db, &pkg_dot_func, true)))
     return NULL;