Bug#53445: Build with -Wall and fix warnings that it generates

Fix various mismatches between function's language linkage. Any
particular function that is declared in C++ but should be callable
from C must have C linkage. Note that function types with different
linkages are also distinct. Thus, if a function type is declared in
C code, it will have C linkage (same if declared in a extern "C"
block).

client/mysql.cc:
  Mismatch between prototype and declaration.
client/mysqltest.cc:
  mysqltest used to be C code. Use C linkage where appropriate.
cmd-line-utils/readline/input.c:
  Isolate unreachable code.
include/my_alloc.h:
  Function type must have C linkage.
include/my_base.h:
  Function type must have C linkage.
include/my_global.h:
  Add helper macros to avoid spurious namespace indentation.
include/mysql.h.pp:
  Update ABI file.
mysys/my_gethwaddr.c:
  Remove stray carriage return and fix coding style.
plugin/semisync/semisync_master_plugin.cc:
  Callback function types have C linkage.
plugin/semisync/semisync_slave_plugin.cc:
  Callback function types have C linkage.
sql/derror.cc:
  Expected function type has C linkage.
sql/field.cc:
  Use helper macro and fix indentation.
sql/handler.cc:
  Expected function type has C linkage.
sql/item_sum.cc:
  Correct function linkages. Remove now unnecessary cast.
sql/item_sum.h:
  Add prototypes with the appropriate linkage as otherwise they
  are distinct.
sql/mysqld.cc:
  Wrap functions in C linkage mode.
sql/opt_range.cc:
  C language linkage is ignored for class member functions.
sql/partition_info.cc:
  Add wrapper functions with C linkage for class member functions.
sql/rpl_utility.h:
  Use helper macro and fix indentation.
sql/sql_class.cc:
  Change type of thd argument -- THD is a class.
  Use helper macro and fix indentation.
sql/sql_class.h:
  Change type of thd argument -- THD is a class.
sql/sql_select.cc:
  Expected function type has C linkage.
sql/sql_select.h:
  Move prototype to sql_test.h
sql/sql_show.cc:
  Expected function type has C linkage.
sql/sql_test.cc:
  Fix required function prototype and fix coding style.
sql/sql_test.h:
  Removed unnecessary export and add another.
storage/myisammrg/ha_myisammrg.cc:
  Expected function type has C linkage.
storage/perfschema/pfs.cc:
  PSI headers are declared with C language linkage, which also
  applies to function types.

4 files changed, 19 insertions, 3 deletions

diff --git a/storage/perfschema/pfs.cc b/storage/perfschema/pfs.cc
index 380801c8677..f5901540ab0 100644
--- a/storage/perfschema/pfs.cc
+++ b/storage/perfschema/pfs.cc
@@ -806,6 +806,10 @@ static int build_prefix(const LEX_STRING *prefix, const char *category,
   }                                                                   \
   return;
 
+/* Use C linkage for the interface functions. */
+
+C_MODE_START
+
 static void register_mutex_v1(const char *category,
                               PSI_mutex_info_v1 *info,
                               int count)
@@ -2054,8 +2058,9 @@ static void* get_interface(int version)
   }
 }
 
+C_MODE_END
+
 struct PSI_bootstrap PFS_bootstrap=
 {
   get_interface
 };
-
diff --git a/storage/perfschema/pfs_instr.cc b/storage/perfschema/pfs_instr.cc
index fb40db02ca3..9507e2d2582 100644
--- a/storage/perfschema/pfs_instr.cc
+++ b/storage/perfschema/pfs_instr.cc
@@ -134,6 +134,10 @@ static PFS_events_waits *thread_history_array= NULL;
 static LF_HASH filename_hash;
 /** True if filename_hash is initialized. */
 static bool filename_hash_inited= false;
+C_MODE_START
+/** Get hash table key for instrumented files. */
+static uchar *filename_hash_get_key(const uchar *, size_t *, my_bool);
+C_MODE_END
 
 /**
   Initialize all the instruments instance buffers.
diff --git a/storage/perfschema/pfs_instr_class.cc b/storage/perfschema/pfs_instr_class.cc
index ac8aa64b0c5..d1535aa851b 100644
--- a/storage/perfschema/pfs_instr_class.cc
+++ b/storage/perfschema/pfs_instr_class.cc
@@ -118,6 +118,10 @@ PFS_instr_class global_table_class=
 static LF_HASH table_share_hash;
 /** True if table_share_hash is initialized. */
 static bool table_share_hash_inited= false;
+C_MODE_START
+/** Get hash table key for instrumented tables. */
+static uchar *table_share_hash_get_key(const uchar *, size_t *, my_bool);
+C_MODE_END
 
 static volatile uint32 file_class_dirty_count= 0;
 static volatile uint32 file_class_allocated_count= 0;
diff --git a/storage/perfschema/pfs_server.cc b/storage/perfschema/pfs_server.cc
index a1216c6ac30..f852a9fe732 100644
--- a/storage/perfschema/pfs_server.cc
+++ b/storage/perfschema/pfs_server.cc
@@ -32,8 +32,11 @@
 
 PFS_global_param pfs_param;
 
+C_MODE_START
 static void destroy_pfs_thread(void *key);
-void cleanup_performance_schema(void);
+C_MODE_END
+
+static void cleanup_performance_schema(void);
 
 struct PSI_bootstrap*
 initialize_performance_schema(const PFS_global_param *param)
@@ -100,7 +103,7 @@ static void destroy_pfs_thread(void *key)
     destroy_thread(pfs);
 }
 
-void cleanup_performance_schema(void)
+static void cleanup_performance_schema(void)
 {
   cleanup_instruments();
   cleanup_sync_class();