MDEV-21907: Fix or disable -Wconversion on GCC 5.3.0 i386

Fix or disable those -Wconversion that were missed by GCC 5.4.0
targeting AMD64.

storage/innobase/handler/ha_innodb.cc

@@ -20939,8 +20939,15 @@ innobase_get_computed_value(
 		}
 
 		if (len == UNIV_SQL_NULL) {
+#if defined __GNUC__ && !defined __clang__ && __GNUC__ < 6
+# pragma GCC diagnostic push
+# pragma GCC diagnostic ignored "-Wconversion" /* GCC 5 may need this here */
+#endif
                         mysql_rec[templ->mysql_null_byte_offset]
                                 |= (byte) templ->mysql_null_bit_mask;
+#if defined __GNUC__ && !defined __clang__ && __GNUC__ < 6
+# pragma GCC diagnostic pop
+#endif
                         memcpy(mysql_rec + templ->mysql_col_offset,
                                static_cast<const byte*>(
 					index->table->vc_templ->default_rec

storage/innobase/ibuf/ibuf0ibuf.cc

@@ -643,7 +643,14 @@ ibuf_bitmap_page_set_bits(
 	} else {
 		ut_ad(val <= 1);
 		b &= static_cast<byte>(~(1U << bit_offset));
+#if defined __GNUC__ && !defined __clang__ && __GNUC__ < 6
+# pragma GCC diagnostic push
+# pragma GCC diagnostic ignored "-Wconversion" /* GCC 5 may need this here */
+#endif
 		b |= static_cast<byte>(val << bit_offset);
+#if defined __GNUC__ && !defined __clang__ && __GNUC__ < 6
+# pragma GCC diagnostic pop
+#endif
 	}
 
 	mtr->write<1,mtr_t::OPT>(*block, map_byte, b);

storage/innobase/page/page0cur.cc

@@ -2094,7 +2094,7 @@ static void page_mem_free(const buf_block_t &block, rec_t *rec,
       ? ((n_heap & 0x8000)
          ? static_cast<uint16_t>(free - rec)
          : static_cast<uint16_t>(free - block.frame))
-      : 0;
+      : uint16_t{0};
     mach_write_to_2(rec - REC_NEXT, next);
   }
   else

storage/innobase/rem/rem0rec.cc

@@ -448,8 +448,9 @@ rec_init_offsets_comp_ordinary(
 	} while (field++, rec_offs_base(offsets)[++i] = len,
 		 i < rec_offs_n_fields(offsets));
 
-	*rec_offs_base(offsets)
-		= static_cast<offset_t>(rec - (lens + 1)) | REC_OFFS_COMPACT | any;
+	*rec_offs_base(offsets) = static_cast<offset_t>((rec - (lens + 1))
+							| REC_OFFS_COMPACT
+							| any);
 }
 
 #ifdef UNIV_DEBUG
@@ -737,8 +738,8 @@ rec_init_offsets(
 		} while (++i < rec_offs_n_fields(offsets));
 
 		*rec_offs_base(offsets)
-			= static_cast<offset_t>(rec - (lens + 1))
-			  | REC_OFFS_COMPACT;
+			= static_cast<offset_t>((rec - (lens + 1))
+						| REC_OFFS_COMPACT);
 	} else {
 		/* Old-style record: determine extra size and end offsets */
 		offs = REC_N_OLD_EXTRA_BYTES;
@@ -1591,7 +1592,14 @@ rec_convert_dtuple_to_rec_comp(
 
 			/* set the null flag if necessary */
 			if (dfield_is_null(field)) {
+#if defined __GNUC__ && !defined __clang__ && __GNUC__ < 6
+# pragma GCC diagnostic push
+# pragma GCC diagnostic ignored "-Wconversion" /* GCC 5 may need this here */
+#endif
 				*nulls |= static_cast<byte>(null_mask);
+#if defined __GNUC__ && !defined __clang__ && __GNUC__ < 6
+# pragma GCC diagnostic pop
+#endif
 				null_mask <<= 1;
 				continue;
 			}
@@ -1626,21 +1634,20 @@ rec_convert_dtuple_to_rec_comp(
 			ut_ad(DATA_BIG_COL(ifield->col));
 			ut_ad(len <= REC_ANTELOPE_MAX_INDEX_COL_LEN
 					+ BTR_EXTERN_FIELD_REF_SIZE);
-			*lens-- = (byte) (len >> 8) | 0xc0;
-			*lens-- = (byte) len;
+			*lens-- = static_cast<byte>(len >> 8 | 0xc0);
+			*lens-- = static_cast<byte>(len);
 		} else {
 			ut_ad(len <= field->type.len
 			      || DATA_LARGE_MTYPE(field->type.mtype)
 			      || !strcmp(index->name,
 					 FTS_INDEX_TABLE_IND_NAME));
 			if (len < 128 || !DATA_BIG_LEN_MTYPE(
-				field->type.len, field->type.mtype)) {
-
-				*lens-- = (byte) len;
+				    field->type.len, field->type.mtype)) {
+				*lens-- = static_cast<byte>(len);
 			} else {
 				ut_ad(len < 16384);
-				*lens-- = (byte) (len >> 8) | 0x80;
-				*lens-- = (byte) len;
+				*lens-- = static_cast<byte>(len >> 8 | 0x80);
+				*lens-- = static_cast<byte>(len);
 			}
 		}
 

storage/innobase/row/row0sel.cc

@@ -2951,8 +2951,15 @@ row_sel_store_mysql_field(
 			UNIV_MEM_ASSERT_RW(prebuilt->default_rec
 					   + templ->mysql_col_offset,
 					   templ->mysql_col_len);
+#if defined __GNUC__ && !defined __clang__ && __GNUC__ < 6
+# pragma GCC diagnostic push
+# pragma GCC diagnostic ignored "-Wconversion" /* GCC 5 may need this here */
+#endif
 			mysql_rec[templ->mysql_null_byte_offset]
 				|= (byte) templ->mysql_null_bit_mask;
+#if defined __GNUC__ && !defined __clang__ && __GNUC__ < 6
+# pragma GCC diagnostic pop
+#endif
 			memcpy(mysql_rec + templ->mysql_col_offset,
 			       (const byte*) prebuilt->default_rec
 			       + templ->mysql_col_offset,
@@ -3048,8 +3055,15 @@ static bool row_sel_store_mysql_rec(
 				&& !prebuilt->m_read_virtual_key)) {
 				/* Initialize the NULL bit. */
 				if (templ->mysql_null_bit_mask) {
+#if defined __GNUC__ && !defined __clang__ && __GNUC__ < 6
+# pragma GCC diagnostic push
+# pragma GCC diagnostic ignored "-Wconversion" /* GCC 5 may need this here */
+#endif
 					mysql_rec[templ->mysql_null_byte_offset]
 						|= (byte) templ->mysql_null_bit_mask;
+#if defined __GNUC__ && !defined __clang__ && __GNUC__ < 6
+# pragma GCC diagnostic pop
+#endif
 				}
 				continue;
 			}
@@ -3084,8 +3098,15 @@ static bool row_sel_store_mysql_rec(
 			}
 
 			if (dfield->len == UNIV_SQL_NULL) {
+#if defined __GNUC__ && !defined __clang__ && __GNUC__ < 6
+# pragma GCC diagnostic push
+# pragma GCC diagnostic ignored "-Wconversion" /* GCC 5 may need this here */
+#endif
 				mysql_rec[templ->mysql_null_byte_offset]
 				|= (byte) templ->mysql_null_bit_mask;
+#if defined __GNUC__ && !defined __clang__ && __GNUC__ < 6
+# pragma GCC diagnostic pop
+#endif
 				memcpy(mysql_rec
 				+ templ->mysql_col_offset,
 				(const byte*) prebuilt->default_rec
@@ -3641,10 +3662,17 @@ row_sel_copy_cached_fields_for_mysql(
 		/* Copy NULL bit of the current field from cached_rec
 		to buf */
 		if (templ->mysql_null_bit_mask) {
+#if defined __GNUC__ && !defined __clang__ && __GNUC__ < 6
+# pragma GCC diagnostic push
+# pragma GCC diagnostic ignored "-Wconversion" /* GCC 5 may need this here */
+#endif
 			buf[templ->mysql_null_byte_offset]
 				^= (buf[templ->mysql_null_byte_offset]
 				    ^ cached_rec[templ->mysql_null_byte_offset])
 				& (byte) templ->mysql_null_bit_mask;
+#if defined __GNUC__ && !defined __clang__ && __GNUC__ < 6
+# pragma GCC diagnostic pop
+#endif
 		}
 	}
 }

storage/innobase/trx/trx0i_s.cc

@@ -184,7 +184,7 @@ static uint16_t wait_lock_get_heap_no(const lock_t* lock)
 {
 	return lock_get_type(lock) == LOCK_REC
 		? static_cast<uint16_t>(lock_rec_find_set_bit(lock))
-		: 0;
+		: uint16_t{0};
 }
 
 /*******************************************************************//**