diff --git a/.github/workflows/push.yml b/.github/workflows/push.yml
index 7e3033ac4bcb1..8befdd3c84251 100644
--- a/.github/workflows/push.yml
+++ b/.github/workflows/push.yml
@@ -123,7 +123,7 @@ jobs:
           configurationParameters: >-
             --${{ matrix.debug && 'enable' || 'disable' }}-debug
             --${{ matrix.zts && 'enable' || 'disable' }}-zts
-            ${{ matrix.asan && 'CFLAGS="-fsanitize=undefined,address -DZEND_TRACK_ARENA_ALLOC" LDFLAGS="-fsanitize=undefined,address" CC=clang-16 CXX=clang++-16' || '' }}
+            ${{ matrix.asan && 'CFLAGS="-std=c99 -fsanitize=undefined,address -DZEND_TRACK_ARENA_ALLOC" LDFLAGS="-fsanitize=undefined,address" CC=clang-16 CXX=clang++-16' || '' }}
           skipSlow: ${{ matrix.asan }}
       - name: make
         run: make -j$(/usr/bin/nproc) >/dev/null
diff --git a/TSRM/TSRM.c b/TSRM/TSRM.c
index 81136bee4daa9..8a74a2f122501 100644
--- a/TSRM/TSRM.c
+++ b/TSRM/TSRM.c
@@ -781,7 +781,7 @@ TSRM_API size_t tsrm_get_ls_cache_tcb_offset(void)
 	!defined(__HAIKU__)
 	size_t ret;
 
-	asm ("movq _tsrm_ls_cache@gottpoff(%%rip),%0"
+	__asm__ ("movq _tsrm_ls_cache@gottpoff(%%rip),%0"
           : "=r" (ret));
 	return ret;
 #elif defined(__i386__) && defined(__GNUC__) && !defined(__FreeBSD__) && \
@@ -789,7 +789,7 @@ TSRM_API size_t tsrm_get_ls_cache_tcb_offset(void)
 	!defined(__HAIKU__)
 	size_t ret;
 
-	asm ("leal _tsrm_ls_cache@ntpoff,%0"
+	__asm__ ("leal _tsrm_ls_cache@ntpoff,%0"
           : "=r" (ret));
 	return ret;
 #elif defined(__aarch64__)
diff --git a/Zend/zend_builtin_functions.h b/Zend/zend_builtin_functions.h
index 237b34b2927be..41ee76ee2f5a7 100644
--- a/Zend/zend_builtin_functions.h
+++ b/Zend/zend_builtin_functions.h
@@ -22,12 +22,12 @@
 
 #include "zend_types.h"
 
-typedef struct _zval_struct zval;
+struct _zval_struct;
 
 zend_result zend_startup_builtin_functions(void);
 
 BEGIN_EXTERN_C()
-ZEND_API void zend_fetch_debug_backtrace(zval *return_value, int skip_last, int options, int limit);
+ZEND_API void zend_fetch_debug_backtrace(struct _zval_struct *return_value, int skip_last, int options, int limit);
 END_EXTERN_C()
 
 #endif /* ZEND_BUILTIN_FUNCTIONS_H */
diff --git a/Zend/zend_compile.h b/Zend/zend_compile.h
index c7e31877b5cd2..8c6bf4dec65e4 100644
--- a/Zend/zend_compile.h
+++ b/Zend/zend_compile.h
@@ -189,7 +189,7 @@ typedef struct _zend_live_range {
 	uint32_t end;
 } zend_live_range;
 
-typedef struct _zend_property_info zend_property_info;
+struct _zend_property_info;
 
 /* Compilation context that is different for each op array. */
 typedef struct _zend_oparray_context {
@@ -204,7 +204,7 @@ typedef struct _zend_oparray_context {
 	int        last_brk_cont;
 	zend_brk_cont_element *brk_cont_array;
 	HashTable *labels;
-	const zend_property_info *active_property_info;
+	const struct _zend_property_info *active_property_info;
 	zend_property_hook_kind active_property_hook_kind;
 	bool       in_jmp_frameless_branch;
 } zend_oparray_context;
@@ -426,7 +426,7 @@ typedef struct _zend_property_info {
 	HashTable *attributes;
 	zend_class_entry *ce;
 	zend_type type;
-	const zend_property_info *prototype;
+	const struct _zend_property_info *prototype;
 	zend_function **hooks;
 } zend_property_info;
 
diff --git a/Zend/zend_frameless_function.c b/Zend/zend_frameless_function.c
index 7ccda0cfb5702..d34aaa5cf9ccd 100644
--- a/Zend/zend_frameless_function.c
+++ b/Zend/zend_frameless_function.c
@@ -17,6 +17,7 @@
 #include <stddef.h>
 
 #include "zend_frameless_function.h"
+#include "zend_types.h"
 
 size_t zend_flf_count = 0;
 size_t zend_flf_capacity = 0;
diff --git a/Zend/zend_frameless_function.h b/Zend/zend_frameless_function.h
index d64ca7ee15e2f..f082b84cc3cd4 100644
--- a/Zend/zend_frameless_function.h
+++ b/Zend/zend_frameless_function.h
@@ -103,19 +103,18 @@
 
 BEGIN_EXTERN_C()
 
-typedef struct _zval_struct zval;
-typedef struct _zend_op zend_op;
-typedef union _zend_function zend_function;
+struct _zval_struct;
+union _zend_function;
 
-typedef void (*zend_frameless_function_0)(zval *return_value);
-typedef void (*zend_frameless_function_1)(zval *return_value, zval *op1);
-typedef void (*zend_frameless_function_2)(zval *return_value, zval *op1, zval *op2);
-typedef void (*zend_frameless_function_3)(zval *return_value, zval *op1, zval *op2, zval *op3);
+typedef void (*zend_frameless_function_0)(struct _zval_struct *return_value);
+typedef void (*zend_frameless_function_1)(struct _zval_struct *return_value, struct _zval_struct *op1);
+typedef void (*zend_frameless_function_2)(struct _zval_struct *return_value, struct _zval_struct *op1, struct _zval_struct *op2);
+typedef void (*zend_frameless_function_3)(struct _zval_struct *return_value, struct _zval_struct *op1, struct _zval_struct *op2, struct _zval_struct *op3);
 
 extern size_t zend_flf_count;
 extern size_t zend_flf_capacity;
 ZEND_API extern void **zend_flf_handlers;
-ZEND_API extern zend_function **zend_flf_functions;
+ZEND_API extern union _zend_function **zend_flf_functions;
 
 typedef struct {
 	void *handler;
diff --git a/Zend/zend_ini_scanner.h b/Zend/zend_ini_scanner.h
index 62546413c7cb2..b653f0307b723 100644
--- a/Zend/zend_ini_scanner.h
+++ b/Zend/zend_ini_scanner.h
@@ -22,7 +22,7 @@
 
 #include "zend_types.h"
 
-typedef struct _zend_file_handle zend_file_handle;
+struct _zend_file_handle;
 
 /* Scanner modes */
 #define ZEND_INI_SCANNER_NORMAL 0 /* Normal mode. [DEFAULT] */
@@ -32,7 +32,7 @@ typedef struct _zend_file_handle zend_file_handle;
 BEGIN_EXTERN_C()
 ZEND_COLD int zend_ini_scanner_get_lineno(void);
 ZEND_COLD const char *zend_ini_scanner_get_filename(void);
-zend_result zend_ini_open_file_for_scanning(zend_file_handle *fh, int scanner_mode);
+zend_result zend_ini_open_file_for_scanning(struct _zend_file_handle *fh, int scanner_mode);
 zend_result zend_ini_prepare_string_for_scanning(const char *str, int scanner_mode);
 int ini_lex(zval *ini_lval);
 void shutdown_ini_scanner(void);
diff --git a/Zend/zend_map_ptr.h b/Zend/zend_map_ptr.h
index 7a0d853dbd166..75e9ca9d66576 100644
--- a/Zend/zend_map_ptr.h
+++ b/Zend/zend_map_ptr.h
@@ -21,7 +21,7 @@
 
 #include "zend_portability.h"
 
-typedef struct _zend_string zend_string;
+struct _zend_string;
 
 #define ZEND_MAP_PTR_KIND_PTR           0
 #define ZEND_MAP_PTR_KIND_PTR_OR_OFFSET 1
@@ -76,7 +76,7 @@ BEGIN_EXTERN_C()
 ZEND_API void  zend_map_ptr_reset(void);
 ZEND_API void *zend_map_ptr_new(void);
 ZEND_API void  zend_map_ptr_extend(size_t last);
-ZEND_API void zend_alloc_ce_cache(zend_string *type_name);
+ZEND_API void zend_alloc_ce_cache(struct _zend_string *type_name);
 
 END_EXTERN_C()
 
diff --git a/Zend/zend_object_handlers.h b/Zend/zend_object_handlers.h
index 730b110eccd37..05ae3249fcf79 100644
--- a/Zend/zend_object_handlers.h
+++ b/Zend/zend_object_handlers.h
@@ -304,10 +304,10 @@ ZEND_API HashTable *zend_std_get_properties_for(zend_object *obj, zend_prop_purp
  * consumers of the get_properties_for API. */
 ZEND_API HashTable *zend_get_properties_for(zval *obj, zend_prop_purpose purpose);
 
-typedef struct _zend_property_info zend_property_info;
+struct _zend_property_info;
 
 ZEND_API zend_function *zend_get_property_hook_trampoline(
-	const zend_property_info *prop_info,
+	const struct _zend_property_info *prop_info,
 	zend_property_hook_kind kind, zend_string *prop_name);
 
 #define zend_release_properties(ht) do { \
diff --git a/Zend/zend_property_hooks.h b/Zend/zend_property_hooks.h
index 3793fa1a683cb..d08e70906e805 100644
--- a/Zend/zend_property_hooks.h
+++ b/Zend/zend_property_hooks.h
@@ -23,19 +23,21 @@
 
 BEGIN_EXTERN_C()
 
-typedef struct _zend_array zend_array;
-typedef struct _zend_class_entry zend_class_entry;
-typedef struct _zend_object zend_object;
-typedef struct _zend_object_iterator zend_object_iterator;
-typedef struct _zval_struct zval;
+/* Intentionally avoid typedef because of C99 redeclaration errors. */
+struct _zend_array;
+struct _zend_class_entry;
+struct _zend_object;
+struct _zend_object_iterator;
+struct _zval_struct;
 
 typedef enum {
 	ZEND_PROPERTY_HOOK_GET = 0,
 	ZEND_PROPERTY_HOOK_SET = 1,
 } zend_property_hook_kind;
 
-ZEND_API zend_object_iterator *zend_hooked_object_get_iterator(zend_class_entry *ce, zval *object, int by_ref);
-ZEND_API zend_array *zend_hooked_object_build_properties(zend_object *zobj);
+ZEND_API struct _zend_object_iterator *zend_hooked_object_get_iterator(
+	struct _zend_class_entry *ce, struct _zval_struct *object, int by_ref);
+ZEND_API struct _zend_array *zend_hooked_object_build_properties(struct _zend_object *zobj);
 
 END_EXTERN_C()
 
diff --git a/Zend/zend_smart_str_public.h b/Zend/zend_smart_str_public.h
index 6a3b526254e48..17ba9c33ed819 100644
--- a/Zend/zend_smart_str_public.h
+++ b/Zend/zend_smart_str_public.h
@@ -19,11 +19,11 @@
 
 #include <stddef.h>
 
-typedef struct _zend_string zend_string;
+struct _zend_string;
 
 typedef struct {
 	/** See smart_str_extract() */
-	zend_string *s;
+	struct _zend_string *s;
 	size_t a;
 } smart_str;
 
diff --git a/Zend/zend_vm.h b/Zend/zend_vm.h
index c9c41c75c72a2..c7333280b7f90 100644
--- a/Zend/zend_vm.h
+++ b/Zend/zend_vm.h
@@ -21,18 +21,18 @@
 
 #include "zend_portability.h"
 
-typedef struct _zend_op zend_op;
-typedef struct _zend_execute_data zend_execute_data;
+struct _zend_op;
+struct _zend_execute_data;
 
 BEGIN_EXTERN_C()
 
-ZEND_API void ZEND_FASTCALL zend_vm_set_opcode_handler(zend_op* opcode);
-ZEND_API void ZEND_FASTCALL zend_vm_set_opcode_handler_ex(zend_op* opcode, uint32_t op1_info, uint32_t op2_info, uint32_t res_info);
-ZEND_API void ZEND_FASTCALL zend_serialize_opcode_handler(zend_op *op);
-ZEND_API void ZEND_FASTCALL zend_deserialize_opcode_handler(zend_op *op);
-ZEND_API const void* ZEND_FASTCALL zend_get_opcode_handler_func(const zend_op *op);
-ZEND_API const zend_op *zend_get_halt_op(void);
-ZEND_API int ZEND_FASTCALL zend_vm_call_opcode_handler(zend_execute_data *ex);
+ZEND_API void ZEND_FASTCALL zend_vm_set_opcode_handler(struct _zend_op* opcode);
+ZEND_API void ZEND_FASTCALL zend_vm_set_opcode_handler_ex(struct _zend_op* opcode, uint32_t op1_info, uint32_t op2_info, uint32_t res_info);
+ZEND_API void ZEND_FASTCALL zend_serialize_opcode_handler(struct _zend_op *op);
+ZEND_API void ZEND_FASTCALL zend_deserialize_opcode_handler(struct _zend_op *op);
+ZEND_API const void* ZEND_FASTCALL zend_get_opcode_handler_func(const struct _zend_op *op);
+ZEND_API const struct _zend_op *zend_get_halt_op(void);
+ZEND_API int ZEND_FASTCALL zend_vm_call_opcode_handler(struct _zend_execute_data *ex);
 ZEND_API int zend_vm_kind(void);
 ZEND_API bool zend_gcc_global_regs(void);
 
diff --git a/ext/bcmath/libbcmath/src/convert.c b/ext/bcmath/libbcmath/src/convert.c
index bf3d9a9a415bf..a1d99b302a256 100644
--- a/ext/bcmath/libbcmath/src/convert.c
+++ b/ext/bcmath/libbcmath/src/convert.c
@@ -16,7 +16,6 @@
 
 #include "bcmath.h"
 #include "convert.h"
-#include "private.h"
 #ifdef __SSE2__
 # include <emmintrin.h>
 #endif
diff --git a/ext/bcmath/libbcmath/src/recmul.c b/ext/bcmath/libbcmath/src/recmul.c
index 3341396236e67..49bada7f2d8e6 100644
--- a/ext/bcmath/libbcmath/src/recmul.c
+++ b/ext/bcmath/libbcmath/src/recmul.c
@@ -33,7 +33,6 @@
 #include <stddef.h>
 #include <assert.h>
 #include <stdbool.h>
-#include "private.h"
 #include "convert.h"
 #include "zend_alloc.h"
 
diff --git a/ext/bcmath/libbcmath/src/str2num.c b/ext/bcmath/libbcmath/src/str2num.c
index a46ae6a2c9d73..3595174926f4e 100644
--- a/ext/bcmath/libbcmath/src/str2num.c
+++ b/ext/bcmath/libbcmath/src/str2num.c
@@ -31,7 +31,6 @@
 
 #include "bcmath.h"
 #include "convert.h"
-#include "private.h"
 #include <stdbool.h>
 #include <stddef.h>
 #ifdef __SSE2__
diff --git a/ext/dom/html5_parser.c b/ext/dom/html5_parser.c
index 0d7d2b9e7249d..1101b542a5d8a 100644
--- a/ext/dom/html5_parser.c
+++ b/ext/dom/html5_parser.c
@@ -30,6 +30,8 @@
 #include <libxml/parserInternals.h>
 #include <libxml/HTMLtree.h>
 
+typedef struct php_dom_ns_magic_token php_dom_ns_magic_token;
+
 #define WORK_LIST_INIT_SIZE 128
 /* libxml2 reserves 2 pointer-sized words for interned strings */
 #define LXML_INTERNED_STRINGS_SIZE (sizeof(void *) * 2)
diff --git a/ext/dom/html5_parser.h b/ext/dom/html5_parser.h
index a56166639a602..d2c937cd874f7 100644
--- a/ext/dom/html5_parser.h
+++ b/ext/dom/html5_parser.h
@@ -66,12 +66,15 @@ void lexbor_libxml2_bridge_parse_set_error_callbacks(
     lexbor_libxml2_bridge_tokenizer_error_reporter tokenizer_error_reporter,
     lexbor_libxml2_bridge_tree_error_reporter tree_error_reporter
 );
+
+struct php_dom_private_data;
+
 lexbor_libxml2_bridge_status lexbor_libxml2_bridge_convert_document(
     lxb_html_document_t *document,
     xmlDocPtr *doc_out,
     bool compact_text_nodes,
     bool create_default_ns,
-    php_dom_private_data *private_data
+    struct php_dom_private_data *private_data
 );
 lexbor_libxml2_bridge_status lexbor_libxml2_bridge_convert_fragment(
     lxb_dom_node_t *start_node,
@@ -79,7 +82,7 @@ lexbor_libxml2_bridge_status lexbor_libxml2_bridge_convert_fragment(
     xmlNodePtr *fragment_out,
     bool compact_text_nodes,
     bool create_default_ns,
-    php_dom_private_data *private_data
+    struct php_dom_private_data *private_data
 );
 void lexbor_libxml2_bridge_report_errors(
     const lexbor_libxml2_bridge_parse_context *ctx,
diff --git a/ext/dom/namespace_compat.c b/ext/dom/namespace_compat.c
index 7a3bd68b0111a..4116639c6b272 100644
--- a/ext/dom/namespace_compat.c
+++ b/ext/dom/namespace_compat.c
@@ -25,6 +25,8 @@
 #include "private_data.h"
 #include "internal_helpers.h"
 
+typedef struct php_dom_ns_magic_token php_dom_ns_magic_token;
+
 /* The actual value of these doesn't matter as long as they serve as a unique ID.
  * They need to be pointers because the `_private` field is a pointer, however we can choose the contents ourselves.
  * We need keep these at least 4-byte aligned because the pointer may be tagged (although for now 2 byte alignment works too).
diff --git a/ext/dom/namespace_compat.h b/ext/dom/namespace_compat.h
index 23c80acc7fd78..3cb4ac3f489b3 100644
--- a/ext/dom/namespace_compat.h
+++ b/ext/dom/namespace_compat.h
@@ -28,35 +28,32 @@
 #define DOM_XMLNS_NS_URI "http://www.w3.org/2000/xmlns/"
 
 struct php_dom_ns_magic_token;
-typedef struct php_dom_ns_magic_token php_dom_ns_magic_token;
-
 struct php_dom_libxml_ns_mapper;
-typedef struct php_dom_libxml_ns_mapper php_dom_libxml_ns_mapper;
 
-PHP_DOM_EXPORT extern const php_dom_ns_magic_token *php_dom_ns_is_html_magic_token;
-PHP_DOM_EXPORT extern const php_dom_ns_magic_token *php_dom_ns_is_mathml_magic_token;
-PHP_DOM_EXPORT extern const php_dom_ns_magic_token *php_dom_ns_is_svg_magic_token;
-PHP_DOM_EXPORT extern const php_dom_ns_magic_token *php_dom_ns_is_xlink_magic_token;
-PHP_DOM_EXPORT extern const php_dom_ns_magic_token *php_dom_ns_is_xml_magic_token;
-PHP_DOM_EXPORT extern const php_dom_ns_magic_token *php_dom_ns_is_xmlns_magic_token;
+PHP_DOM_EXPORT extern const struct php_dom_ns_magic_token *php_dom_ns_is_html_magic_token;
+PHP_DOM_EXPORT extern const struct php_dom_ns_magic_token *php_dom_ns_is_mathml_magic_token;
+PHP_DOM_EXPORT extern const struct php_dom_ns_magic_token *php_dom_ns_is_svg_magic_token;
+PHP_DOM_EXPORT extern const struct php_dom_ns_magic_token *php_dom_ns_is_xlink_magic_token;
+PHP_DOM_EXPORT extern const struct php_dom_ns_magic_token *php_dom_ns_is_xml_magic_token;
+PHP_DOM_EXPORT extern const struct php_dom_ns_magic_token *php_dom_ns_is_xmlns_magic_token;
 
 /* These functions make it possible to make a namespace declaration also visible as an attribute by
  * creating an equivalent attribute node. */
 
-PHP_DOM_EXPORT xmlNsPtr php_dom_libxml_ns_mapper_ensure_html_ns(php_dom_libxml_ns_mapper *mapper);
-PHP_DOM_EXPORT xmlNsPtr php_dom_libxml_ns_mapper_ensure_prefixless_xmlns_ns(php_dom_libxml_ns_mapper *mapper);
-PHP_DOM_EXPORT xmlNsPtr php_dom_libxml_ns_mapper_get_ns(php_dom_libxml_ns_mapper *mapper, zend_string *prefix, zend_string *uri);
-PHP_DOM_EXPORT xmlNsPtr php_dom_libxml_ns_mapper_get_ns_raw_prefix_string(php_dom_libxml_ns_mapper *mapper, const xmlChar *prefix, size_t prefix_len, zend_string *uri);
-PHP_DOM_EXPORT xmlNsPtr php_dom_libxml_ns_mapper_get_ns_raw_strings_nullsafe(php_dom_libxml_ns_mapper *mapper, const char *prefix, const char *uri);
+PHP_DOM_EXPORT xmlNsPtr php_dom_libxml_ns_mapper_ensure_html_ns(struct php_dom_libxml_ns_mapper *mapper);
+PHP_DOM_EXPORT xmlNsPtr php_dom_libxml_ns_mapper_ensure_prefixless_xmlns_ns(struct php_dom_libxml_ns_mapper *mapper);
+PHP_DOM_EXPORT xmlNsPtr php_dom_libxml_ns_mapper_get_ns(struct php_dom_libxml_ns_mapper *mapper, zend_string *prefix, zend_string *uri);
+PHP_DOM_EXPORT xmlNsPtr php_dom_libxml_ns_mapper_get_ns_raw_prefix_string(struct php_dom_libxml_ns_mapper *mapper, const xmlChar *prefix, size_t prefix_len, zend_string *uri);
+PHP_DOM_EXPORT xmlNsPtr php_dom_libxml_ns_mapper_get_ns_raw_strings_nullsafe(struct php_dom_libxml_ns_mapper *mapper, const char *prefix, const char *uri);
 
-PHP_DOM_EXPORT php_dom_libxml_ns_mapper *php_dom_get_ns_mapper(dom_object *object);
-PHP_DOM_EXPORT void php_dom_ns_compat_mark_attribute_list(php_dom_libxml_ns_mapper *mapper, xmlNodePtr node);
-PHP_DOM_EXPORT void php_dom_libxml_reconcile_modern(php_dom_libxml_ns_mapper *ns_mapper, xmlNodePtr node);
+PHP_DOM_EXPORT struct php_dom_libxml_ns_mapper *php_dom_get_ns_mapper(dom_object *object);
+PHP_DOM_EXPORT void php_dom_ns_compat_mark_attribute_list(struct php_dom_libxml_ns_mapper *mapper, xmlNodePtr node);
+PHP_DOM_EXPORT void php_dom_libxml_reconcile_modern(struct php_dom_libxml_ns_mapper *ns_mapper, xmlNodePtr node);
 PHP_DOM_EXPORT void php_dom_reconcile_attribute_namespace_after_insertion(xmlAttrPtr attrp);
-PHP_DOM_EXPORT xmlAttrPtr php_dom_ns_compat_mark_attribute(php_dom_libxml_ns_mapper *mapper, xmlNodePtr node, xmlNsPtr ns);
+PHP_DOM_EXPORT xmlAttrPtr php_dom_ns_compat_mark_attribute(struct php_dom_libxml_ns_mapper *mapper, xmlNodePtr node, xmlNsPtr ns);
 
-PHP_DOM_EXPORT bool php_dom_ns_is_fast(const xmlNode *nodep, const php_dom_ns_magic_token *magic_token);
-PHP_DOM_EXPORT bool php_dom_ns_is_fast_ex(xmlNsPtr ns, const php_dom_ns_magic_token *magic_token);
+PHP_DOM_EXPORT bool php_dom_ns_is_fast(const xmlNode *nodep, const struct php_dom_ns_magic_token *magic_token);
+PHP_DOM_EXPORT bool php_dom_ns_is_fast_ex(xmlNsPtr ns, const struct php_dom_ns_magic_token *magic_token);
 PHP_DOM_EXPORT bool php_dom_ns_is_html_and_document_is_html(const xmlNode *nodep);
 
 typedef struct php_dom_in_scope_ns {
@@ -65,7 +62,7 @@ typedef struct php_dom_in_scope_ns {
    bool origin_is_ns_compat;
 } php_dom_in_scope_ns;
 
-PHP_DOM_EXPORT php_dom_in_scope_ns php_dom_get_in_scope_ns(php_dom_libxml_ns_mapper *ns_mapper, const xmlNode *node, bool ignore_elements);
+PHP_DOM_EXPORT php_dom_in_scope_ns php_dom_get_in_scope_ns(struct php_dom_libxml_ns_mapper *ns_mapper, const xmlNode *node, bool ignore_elements);
 PHP_DOM_EXPORT php_dom_in_scope_ns php_dom_get_in_scope_ns_legacy(const xmlNode *node);
 PHP_DOM_EXPORT void php_dom_in_scope_ns_destroy(php_dom_in_scope_ns *in_scope_ns);
 
diff --git a/ext/dom/php_dom.h b/ext/dom/php_dom.h
index 0f19a05501a64..6dd3203a0ad0f 100644
--- a/ext/dom/php_dom.h
+++ b/ext/dom/php_dom.h
@@ -115,7 +115,6 @@ typedef enum dom_iterator_type {
 } dom_iterator_type;
 
 struct php_dom_libxml_ns_mapper;
-typedef struct php_dom_libxml_ns_mapper php_dom_libxml_ns_mapper;
 
 static inline dom_object_namespace_node *php_dom_namespace_node_obj_from_obj(zend_object *obj) {
 	return (dom_object_namespace_node*)((char*)(obj) - XtOffsetOf(dom_object_namespace_node, dom.std));
@@ -176,7 +175,7 @@ xmlDocPtr php_dom_create_html_doc(void);
 xmlEntityPtr dom_entity_reference_fetch_and_sync_declaration(xmlNodePtr reference);
 void dom_set_xml_class(php_libxml_ref_obj *document);
 const char *dom_locate_a_namespace(const xmlNode *node, const zend_string *prefix);
-void dom_mark_namespaces_as_attributes_too(php_dom_libxml_ns_mapper *ns_mapper, xmlDocPtr doc);
+void dom_mark_namespaces_as_attributes_too(struct php_dom_libxml_ns_mapper *ns_mapper, xmlDocPtr doc);
 bool dom_compare_value(const xmlAttr *attr, const xmlChar *value);
 void dom_attr_value_will_change(dom_object *obj, xmlAttrPtr attrp);
 bool php_dom_create_nullable_object(xmlNodePtr obj, zval *return_value, dom_object *domobj);
@@ -216,7 +215,7 @@ xmlNodePtr php_dom_named_node_map_get_item(dom_nnodemap_object *objmap, zend_lon
 void php_dom_named_node_map_get_item_into_zval(dom_nnodemap_object *objmap, zend_long index, zval *return_value);
 int php_dom_get_namednodemap_length(dom_object *obj);
 
-xmlNodePtr dom_clone_node(php_dom_libxml_ns_mapper *ns_mapper, xmlNodePtr node, xmlDocPtr doc, bool recursive);
+xmlNodePtr dom_clone_node(struct php_dom_libxml_ns_mapper *ns_mapper, xmlNodePtr node, xmlDocPtr doc, bool recursive);
 
 #define DOM_GET_INTERN(__id, __intern) { \
 	__intern = Z_DOMOBJ_P(__id); \
diff --git a/ext/dom/private_data.h b/ext/dom/private_data.h
index ead6c75caf249..50d175081c321 100644
--- a/ext/dom/private_data.h
+++ b/ext/dom/private_data.h
@@ -19,30 +19,23 @@
 
 #include "xml_common.h"
 
-struct php_dom_libxml_ns_mapper {
+struct php_libxml_private_data_header;
+
+typedef struct php_dom_libxml_ns_mapper {
 	/* This is used almost all the time for HTML documents, so it makes sense to cache this. */
 	xmlNsPtr html_ns;
 	/* Used for every prefixless namespace declaration in XML, so also very common. */
 	xmlNsPtr prefixless_xmlns_ns;
 	HashTable uri_to_prefix_map;
-};
+} php_dom_libxml_ns_mapper;
 
 typedef struct php_dom_private_data {
-	php_libxml_private_data_header header;
+	struct php_libxml_private_data_header header;
 	struct php_dom_libxml_ns_mapper ns_mapper;
 	HashTable *template_fragments;
 } php_dom_private_data;
 
-typedef struct php_libxml_private_data_header php_libxml_private_data_header;
-struct php_libxml_private_data_header;
-
-struct php_dom_private_data;
-typedef struct php_dom_private_data php_dom_private_data;
-
-struct php_dom_libxml_ns_mapper;
-typedef struct php_dom_libxml_ns_mapper php_dom_libxml_ns_mapper;
-
-php_libxml_private_data_header *php_dom_libxml_private_data_header(php_dom_private_data *private_data);
+struct php_libxml_private_data_header *php_dom_libxml_private_data_header(php_dom_private_data *private_data);
 php_dom_libxml_ns_mapper *php_dom_ns_mapper_from_private(php_dom_private_data *private_data);
 php_dom_private_data *php_dom_private_data_create(void);
 void php_dom_private_data_destroy(php_dom_private_data *data);
diff --git a/ext/dom/xml_common.h b/ext/dom/xml_common.h
index 8e5734d5a914e..cf8fe3be393bd 100644
--- a/ext/dom/xml_common.h
+++ b/ext/dom/xml_common.h
@@ -81,12 +81,11 @@ PHP_DOM_EXPORT xmlNodePtr dom_object_get_node(dom_object *obj);
 	DOM_GET_OBJ(__ptr, __id, __prtype, __intern);
 
 struct php_dom_private_data;
-typedef struct php_dom_private_data php_dom_private_data;
 
-static zend_always_inline php_dom_private_data *php_dom_get_private_data(dom_object *intern)
+static zend_always_inline struct php_dom_private_data *php_dom_get_private_data(dom_object *intern)
 {
 	ZEND_ASSERT(intern->document != NULL);
-	return (php_dom_private_data *) intern->document->private_data;
+	return (struct php_dom_private_data *) intern->document->private_data;
 }
 
 static zend_always_inline xmlNodePtr php_dom_next_in_tree_order(const xmlNode *nodep, const xmlNode *basep)
diff --git a/ext/dom/xml_serializer.h b/ext/dom/xml_serializer.h
index 2d5c3bd84277b..60b1d0ea97fc9 100644
--- a/ext/dom/xml_serializer.h
+++ b/ext/dom/xml_serializer.h
@@ -23,8 +23,7 @@
 #include <libxml/xmlIO.h>
 
 struct php_dom_private_data;
-typedef struct php_dom_private_data php_dom_private_data;
 
-int dom_xml_serialize(xmlSaveCtxtPtr ctx, xmlOutputBufferPtr out, xmlNodePtr node, bool format, bool require_well_formed, php_dom_private_data *private_data);
+int dom_xml_serialize(xmlSaveCtxtPtr ctx, xmlOutputBufferPtr out, xmlNodePtr node, bool format, bool require_well_formed, struct php_dom_private_data *private_data);
 
 #endif
diff --git a/ext/opcache/jit/ir/ir.h b/ext/opcache/jit/ir/ir.h
index cf7580dc7496a..f7ed46f114cd9 100644
--- a/ext/opcache/jit/ir/ir.h
+++ b/ext/opcache/jit/ir/ir.h
@@ -477,7 +477,7 @@ typedef struct _ir_insn {
 } ir_insn;
 
 /* IR Hash Tables API (private) */
-typedef struct _ir_hashtab ir_hashtab;
+struct _ir_hashtab;
 
 /* IR String Tables API (implementation in ir_strtab.c) */
 typedef struct _ir_strtab {
@@ -580,7 +580,7 @@ struct _ir_ctx {
 	int32_t            status;                  /* non-zero error code (see IR_ERROR_... macros), app may use negative codes */
 	ir_ref             fold_cse_limit;          /* CSE finds identical insns backward from "insn_count" to "fold_cse_limit" */
 	ir_insn            fold_insn;               /* temporary storage for folding engine */
-	ir_hashtab        *binding;
+	struct _ir_hashtab *binding;
 	ir_use_list       *use_lists;               /* def->use lists for each instruction */
 	ir_ref            *use_edges;               /* the actual uses: use = ctx->use_edges[ctx->use_lists[def].refs + n] */
 	ir_ref             use_edges_count;         /* number of elements in use_edges[] array */
diff --git a/ext/opcache/jit/ir/ir_x86.dasc b/ext/opcache/jit/ir/ir_x86.dasc
index 1fa7001198c94..aaf0f9ddd45a2 100644
--- a/ext/opcache/jit/ir/ir_x86.dasc
+++ b/ext/opcache/jit/ir/ir_x86.dasc
@@ -10852,7 +10852,7 @@ next_block:;
 
 		do {
 			/* _cldemote(p); */
-			asm volatile(".byte 0x0f, 0x1c, 0x06" :: "S" (p));
+			__asm__ volatile(".byte 0x0f, 0x1c, 0x06" :: "S" (p));
 			p += 64;
 		} while (p < start + size);
 	}
diff --git a/ext/opcache/jit/zend_jit_ir.c b/ext/opcache/jit/zend_jit_ir.c
index 80099291d886d..9f86cf61ffb3b 100644
--- a/ext/opcache/jit/zend_jit_ir.c
+++ b/ext/opcache/jit/zend_jit_ir.c
@@ -3279,7 +3279,7 @@ static void zend_jit_setup(void)
 	!defined(__NetBSD__) && !defined(__OpenBSD__) && !defined(__MUSL__)
 		size_t ret;
 
-		asm ("movq _tsrm_ls_cache@gottpoff(%%rip),%0"
+		__asm__ ("movq _tsrm_ls_cache@gottpoff(%%rip),%0"
 			: "=r" (ret));
 		tsrm_ls_cache_tcb_offset = ret;
 #elif defined(__MUSL__)
@@ -3315,7 +3315,7 @@ static void zend_jit_setup(void)
 #if !defined(__FreeBSD__) && !defined(__NetBSD__) && !defined(__OpenBSD__) && !defined(__MUSL__)
 		size_t ret;
 
-		asm ("leal _tsrm_ls_cache@ntpoff,%0\n"
+		__asm__ ("leal _tsrm_ls_cache@ntpoff,%0\n"
 			: "=a" (ret));
 		tsrm_ls_cache_tcb_offset = ret;
 #else
diff --git a/ext/random/php_random.h b/ext/random/php_random.h
index e4aa32126671e..1ed741c5c8f44 100644
--- a/ext/random/php_random.h
+++ b/ext/random/php_random.h
@@ -37,10 +37,10 @@
 
 PHPAPI double php_combined_lcg(void);
 
-typedef struct _php_random_fallback_seed_state php_random_fallback_seed_state;
+struct _php_random_fallback_seed_state;
 
 PHPAPI uint64_t php_random_generate_fallback_seed(void);
-PHPAPI uint64_t php_random_generate_fallback_seed_ex(php_random_fallback_seed_state *state);
+PHPAPI uint64_t php_random_generate_fallback_seed_ex(struct _php_random_fallback_seed_state *state);
 
 static inline zend_long GENERATE_SEED(void)
 {
diff --git a/ext/xsl/xsltprocessor.c b/ext/xsl/xsltprocessor.c
index eaefdb2f8ef7c..e6c49d8521f2e 100644
--- a/ext/xsl/xsltprocessor.c
+++ b/ext/xsl/xsltprocessor.c
@@ -25,6 +25,7 @@
 #include "ext/libxml/php_libxml.h"
 #include "ext/dom/namespace_compat.h"
 
+typedef struct php_dom_libxml_ns_mapper php_dom_libxml_ns_mapper;
 
 static zend_result php_xsl_xslt_apply_params(xsltTransformContextPtr ctxt, HashTable *params)
 {
diff --git a/main/debug_gdb_scripts.c b/main/debug_gdb_scripts.c
index ad03a2c2ba62f..98e57627e2b2b 100644
--- a/main/debug_gdb_scripts.c
+++ b/main/debug_gdb_scripts.c
@@ -6,7 +6,7 @@
  *
  * See https://sourceware.org/gdb/current/onlinedocs/gdb.html/dotdebug_005fgdb_005fscripts-section.html#dotdebug_005fgdb_005fscripts-section
  */
-asm(
+__asm__(
     ".pushsection \".debug_gdb_scripts\", \"MS\",%progbits,1\n"
     ".byte 4 /* Python Text */\n"
     ".ascii \"gdb.inlined-script\\n\"\n"
diff --git a/scripts/gdb/debug_gdb_scripts_gen.php b/scripts/gdb/debug_gdb_scripts_gen.php
index 1b33d9a63aa6e..2667f249fe4bb 100755
--- a/scripts/gdb/debug_gdb_scripts_gen.php
+++ b/scripts/gdb/debug_gdb_scripts_gen.php
@@ -27,7 +27,7 @@
      *
      * See https://sourceware.org/gdb/current/onlinedocs/gdb.html/dotdebug_005fgdb_005fscripts-section.html#dotdebug_005fgdb_005fscripts-section
      */
-    asm(
+    __asm__(
         ".pushsection \".debug_gdb_scripts\", \"MS\",%%progbits,1\n"
         ".byte 4 /* Python Text */\n"
         ".ascii \"gdb.inlined-script\\n\"\n"