Deprecate case-insensitive constants

RFC: https://wiki.php.net/rfc/case_insensitive_constant_deprecation

9 files changed, 263 insertions, 21 deletions

diff --git a/NEWS b/NEWS
index 3fc05e06e3..665b7f9c05 100644
--- a/NEWS
+++ b/NEWS
@@ -7,6 +7,8 @@ PHP                                                                        NEWS
     arguments). (cmb)
   . Fixed bug #76392 (Error relocating sapi/cli/php: unsupported relocation
     type 37). (Peter Kokot)
+  . The declaration and use of case-insensitive constants has been deprecated.
+    (Nikita)
 
 - Filter:
   . Added the 'add_slashes' sanitization mode (FILTER_SANITIZE_ADD_SLASHES). 
diff --git a/UPGRADING b/UPGRADING
index 160a1d3549..abd2ca7f20 100644
--- a/UPGRADING
+++ b/UPGRADING
@@ -258,6 +258,13 @@ FPM:
 4. Deprecated Functionality
 ========================================
 
+Core:
+  . The declaration of case-insensitive constants has been deprecate. Passing
+    true as the third argument to define() will now generate a deprecation
+    warning. The use of case-insensitive constants with a case that differs from
+    the declaration is also deprecated.
+    (RFC: https://wiki.php.net/rfc/case_insensitive_constant_deprecation)
+
 GD:
   . image2wbmp() has been deprecated.
 
diff --git a/Zend/tests/bug46304.phpt b/Zend/tests/bug46304.phpt
index e2e031116d..9898838907 100644
--- a/Zend/tests/bug46304.phpt
+++ b/Zend/tests/bug46304.phpt
@@ -40,6 +40,11 @@ print ns1\ns2\coNSt6 . "\n";
 print NS1\ns2\coNSt1 . "\n";
 ?>
 --EXPECTF--
+Deprecated: define(): Declaration of case-insensitive constants is deprecated in %s on line 6
+
+Deprecated: define(): Declaration of case-insensitive constants is deprecated in %s on line 7
+
+Deprecated: define(): Declaration of case-insensitive constants is deprecated in %s on line 8
 value1
 value1
 value1
@@ -52,13 +57,23 @@ value3
 value4
 value4
 value4
+
+Deprecated: Case-insensitive constants are deprecated. The correct casing for this constant is "NS1\ns2\const4" in %s on line 25
 value4
 value5
 value5
 value5
+
+Deprecated: Case-insensitive constants are deprecated. The correct casing for this constant is "ns1\ns2\const5" in %s on line 30
 value5
+
+Deprecated: Case-insensitive constants are deprecated. The correct casing for this constant is "ns1\NS2\coNSt6" in %s on line 32
 value6
+
+Deprecated: Case-insensitive constants are deprecated. The correct casing for this constant is "ns1\NS2\coNSt6" in %s on line 33
 value6
+
+Deprecated: Case-insensitive constants are deprecated. The correct casing for this constant is "ns1\NS2\coNSt6" in %s on line 34
 value6
 value6
 
diff --git a/Zend/tests/case_insensitive_constant_deprecation.phpt b/Zend/tests/case_insensitive_constant_deprecation.phpt
new file mode 100644
index 0000000000..e7a92c8c4c
--- /dev/null
+++ b/Zend/tests/case_insensitive_constant_deprecation.phpt
@@ -0,0 +1,127 @@
+--TEST--
+Case-insensitive constants are deprecated
+--FILE--
+<?php
+
+namespace {
+    define('FOO', 42, true); // Deprecated
+    define('NS\FOO', 24, true); // Deprecated
+
+    var_dump(FOO); // Ok
+    var_dump(foo); // Deprecated
+
+    var_dump(NS\FOO); // Ok
+    var_dump(ns\FOO); // Ok
+    var_dump(ns\foo); // Deprecated
+
+    var_dump(defined('FOO')); // Ok
+    var_dump(defined('foo')); // Ok
+    var_dump(defined('NS\FOO')); // Ok
+    var_dump(defined('ns\FOO')); // Ok
+    var_dump(defined('ns\foo')); // Ok
+
+    var_dump(constant('FOO')); // Ok
+    var_dump(constant('foo')); // Deprecated
+    var_dump(constant('NS\FOO')); // Ok
+    var_dump(constant('ns\FOO')); // Ok
+    var_dump(constant('ns\foo')); // Deprecated
+}
+
+namespace NS {
+    var_dump(FOO); // Ok
+    var_dump(foo); // Deprecated
+}
+
+namespace ns {
+    var_dump(FOO); // Ok
+    var_dump(foo); // Deprecated
+}
+
+namespace Other {
+    var_dump(FOO); // Ok
+    var_dump(foo); // Deprecated
+
+    var_dump(defined('FOO')); // Ok
+    var_dump(defined('foo')); // Ok
+    var_dump(defined('NS\FOO')); // Ok
+    var_dump(defined('ns\FOO')); // Ok
+    var_dump(defined('ns\foo')); // Ok
+
+    var_dump(constant('FOO')); // Ok
+    var_dump(constant('foo')); // Deprecated
+    var_dump(constant('NS\FOO')); // Ok
+    var_dump(constant('ns\FOO')); // Ok
+    var_dump(constant('ns\foo')); // Deprecated
+
+    const C1 = FOO; // Ok
+    var_dump(C1);
+    const C2 = foo; // Deprecated
+    var_dump(C2);
+    const C3 = 1 + FOO; // Ok
+    var_dump(C3);
+    const C4 = 1 + foo; // Deprecated
+    var_dump(C4);
+}
+
+?>
+--EXPECTF--
+Deprecated: define(): Declaration of case-insensitive constants is deprecated in %s on line 4
+
+Deprecated: define(): Declaration of case-insensitive constants is deprecated in %s on line 5
+int(42)
+
+Deprecated: Case-insensitive constants are deprecated. The correct casing for this constant is "FOO" in %s on line 8
+int(42)
+int(24)
+int(24)
+
+Deprecated: Case-insensitive constants are deprecated. The correct casing for this constant is "NS\FOO" in %s on line 12
+int(24)
+bool(true)
+bool(true)
+bool(true)
+bool(true)
+bool(true)
+int(42)
+
+Deprecated: Case-insensitive constants are deprecated. The correct casing for this constant is "FOO" in %s on line 21
+int(42)
+int(24)
+int(24)
+
+Deprecated: Case-insensitive constants are deprecated. The correct casing for this constant is "NS\FOO" in %s on line 24
+int(24)
+int(24)
+
+Deprecated: Case-insensitive constants are deprecated. The correct casing for this constant is "NS\FOO" in %s on line 29
+int(24)
+int(24)
+
+Deprecated: Case-insensitive constants are deprecated. The correct casing for this constant is "NS\FOO" in %s on line 34
+int(24)
+int(42)
+
+Deprecated: Case-insensitive constants are deprecated. The correct casing for this constant is "FOO" in %s on line 39
+int(42)
+bool(true)
+bool(true)
+bool(true)
+bool(true)
+bool(true)
+int(42)
+
+Deprecated: Case-insensitive constants are deprecated. The correct casing for this constant is "FOO" in %s on line 48
+int(42)
+int(24)
+int(24)
+
+Deprecated: Case-insensitive constants are deprecated. The correct casing for this constant is "NS\FOO" in %s on line 51
+int(24)
+int(42)
+
+Deprecated: Case-insensitive constants are deprecated. The correct casing for this constant is "FOO" in %s on line 55
+int(42)
+int(43)
+
+Deprecated: Case-insensitive constants are deprecated. The correct casing for this constant is "FOO" in %s on line 59
+int(43)
diff --git a/Zend/zend_builtin_functions.c b/Zend/zend_builtin_functions.c
index 57e5d77380..7b6cebff5e 100644
--- a/Zend/zend_builtin_functions.c
+++ b/Zend/zend_builtin_functions.c
@@ -854,7 +854,6 @@ ZEND_FUNCTION(define)
 		case_sensitive = 0;
 	}
 
-	/* class constant, check if there is name and make sure class is valid & exists */
 	if (zend_memnstr(ZSTR_VAL(name), "::", sizeof("::") - 1, ZSTR_VAL(name) + ZSTR_LEN(name))) {
 		zend_error(E_WARNING, "Class constants cannot be defined or redefined");
 		RETURN_FALSE;
@@ -905,7 +904,13 @@ repeat:
 
 	ZVAL_COPY(&c.value, val);
 	zval_ptr_dtor(&val_free);
+
 register_constant:
+	if (non_cs) {
+		zend_error(E_DEPRECATED,
+			"define(): Declaration of case-insensitive constants is deprecated");
+	}
+
 	c.flags = case_sensitive; /* non persistent */
 	c.name = zend_string_copy(name);
 	c.module_number = PHP_USER_CONSTANT;
@@ -928,7 +933,7 @@ ZEND_FUNCTION(defined)
 		Z_PARAM_STR(name)
 	ZEND_PARSE_PARAMETERS_END();
 
-	if (zend_get_constant_ex(name, zend_get_executed_scope(), ZEND_FETCH_CLASS_SILENT)) {
+	if (zend_get_constant_ex(name, zend_get_executed_scope(), ZEND_FETCH_CLASS_SILENT | ZEND_GET_CONSTANT_NO_DEPRECATION_CHECK)) {
 		RETURN_TRUE;
 	} else {
 		RETURN_FALSE;
diff --git a/Zend/zend_constants.c b/Zend/zend_constants.c
index fe1d9e235b..8b68858ad4 100644
--- a/Zend/zend_constants.c
+++ b/Zend/zend_constants.c
@@ -250,7 +250,7 @@ ZEND_API int zend_verify_const_access(zend_class_constant *c, zend_class_entry *
 }
 /* }}} */
 
-ZEND_API zval *zend_get_constant_str(const char *name, size_t name_len)
+static inline zend_constant *zend_get_constant_str_impl(const char *name, size_t name_len)
 {
 	zend_constant *c;
 	ALLOCA_FLAG(use_heap)
@@ -268,10 +268,16 @@ ZEND_API zval *zend_get_constant_str(const char *name, size_t name_len)
 		free_alloca(lcname, use_heap);
 	}
 
+	return c;
+}
+
+ZEND_API zval *zend_get_constant_str(const char *name, size_t name_len)
+{
+	zend_constant *c = zend_get_constant_str_impl(name, name_len);
 	return c ? &c->value : NULL;
 }
 
-ZEND_API zval *zend_get_constant(zend_string *name)
+static inline zend_constant *zend_get_constant_impl(zend_string *name)
 {
     zval *zv;
 	zend_constant *c;
@@ -291,9 +297,32 @@ ZEND_API zval *zend_get_constant(zend_string *name)
 			c = zend_get_special_constant(ZSTR_VAL(name), ZSTR_LEN(name));
 		}
 		free_alloca(lcname, use_heap);
-		return c ? &c->value : NULL;
+		return c;
+	} else {
+		return (zend_constant *) Z_PTR_P(zv);
+	}
+}
+
+ZEND_API zval *zend_get_constant(zend_string *name)
+{
+	zend_constant *c = zend_get_constant_impl(name);
+	return c ? &c->value : NULL;
+}
+
+static zend_bool is_access_deprecated(const zend_constant *c, const char *access_name) {
+	const char *ns_sep = zend_memrchr(ZSTR_VAL(c->name), '\\', ZSTR_LEN(c->name));
+	if (ns_sep) {
+		/* Namespaces are always case-insensitive. Only compare shortname. */
+		size_t shortname_offset = ns_sep - ZSTR_VAL(c->name) + 1;
+		size_t shortname_len = ZSTR_LEN(c->name) - shortname_offset;
+		return memcmp(
+			access_name + shortname_offset,
+			ZSTR_VAL(c->name) + shortname_offset,
+			shortname_len
+		) != 0;
 	} else {
-		return &((zend_constant*)Z_PTR_P(zv))->value;
+		/* No namespace, compare whole name */
+		return memcmp(access_name, ZSTR_VAL(c->name), ZSTR_LEN(c->name)) != 0;
 	}
 }
 
@@ -415,26 +444,45 @@ failure:
 			}
 		}
 		free_alloca(lcname, use_heap);
-		if (c) {
-			return &c->value;
+
+		if (!c) {
+			if (!(flags & IS_CONSTANT_UNQUALIFIED)) {
+				return NULL;
+			}
+
+			/* name requires runtime resolution, need to check non-namespaced name */
+			c = zend_get_constant_str_impl(constant_name, const_name_len);
+			name = constant_name;
 		}
-		/* name requires runtime resolution, need to check non-namespaced name */
-		if ((flags & IS_CONSTANT_UNQUALIFIED) != 0) {
-			return zend_get_constant_str(constant_name, const_name_len);
+	} else {
+		if (cname) {
+			c = zend_get_constant_impl(cname);
+		} else {
+			c = zend_get_constant_str_impl(name, name_len);
 		}
+	}
+
+	if (!c) {
 		return NULL;
 	}
 
-	if (cname) {
-		return zend_get_constant(cname);
-	} else {
-		return zend_get_constant_str(name, name_len);
+	if (!(flags & ZEND_GET_CONSTANT_NO_DEPRECATION_CHECK)) {
+		if (!(c->flags & (CONST_CS|CONST_CT_SUBST)) && is_access_deprecated(c, name)) {
+			zend_error(E_DEPRECATED,
+				"Case-insensitive constants are deprecated. "
+				"The correct casing for this constant is \"%s\"",
+				ZSTR_VAL(c->name));
+		}
 	}
+
+	return &c->value;
 }
 
-ZEND_API zend_constant* ZEND_FASTCALL zend_quick_get_constant(const zval *key, uint32_t flags)
+ZEND_API zend_constant* ZEND_FASTCALL zend_quick_get_constant(
+		const zval *key, uint32_t flags, zend_bool *is_deprecated)
 {
 	zval *zv;
+	const zval *orig_key = key;
 	zend_constant *c = NULL;
 
 	zv = zend_hash_find_ex(EG(zend_constants), Z_STR_P(key), 1);
@@ -461,6 +509,22 @@ ZEND_API zend_constant* ZEND_FASTCALL zend_quick_get_constant(const zval *key, u
 			}
 		}
 	}
+
+	if (!c) {
+		return NULL;
+	}
+
+	if (is_deprecated) {
+		if (c->flags & (CONST_CS|CONST_CT_SUBST)) {
+			/* Constant is case-sensitive or true/false/null */
+			*is_deprecated = 0;
+		} else {
+			zend_bool ns_fallback = key >= orig_key + 2;
+			const zval *access_key = ns_fallback ? orig_key + 2 : orig_key - 1;
+			*is_deprecated = is_access_deprecated(c, Z_STRVAL_P(access_key));
+		}
+	}
+
 	return c;
 }
 
diff --git a/Zend/zend_constants.h b/Zend/zend_constants.h
index 98484debe2..e06d91ee14 100644
--- a/Zend/zend_constants.h
+++ b/Zend/zend_constants.h
@@ -31,6 +31,9 @@
 
 #define	PHP_USER_CONSTANT INT_MAX	/* a constant defined in user space */
 
+/* Flag for zend_get_constant_ex(). Must not class with ZEND_FETCH_CLASS_* flags. */
+#define ZEND_GET_CONSTANT_NO_DEPRECATION_CHECK 0x1000
+
 typedef struct _zend_constant {
 	zval value;
 	zend_string *name;
@@ -79,7 +82,8 @@ ZEND_API int zend_register_constant(zend_constant *c);
 #ifdef ZTS
 void zend_copy_constants(HashTable *target, HashTable *sourc);
 #endif
-ZEND_API zend_constant* ZEND_FASTCALL zend_quick_get_constant(const zval *key, uint32_t flags);
+ZEND_API zend_constant* ZEND_FASTCALL zend_quick_get_constant(
+		const zval *key, uint32_t flags, zend_bool *is_deprecated);
 END_EXTERN_C()
 
 #define ZEND_CONSTANT_DTOR free_zend_constant
diff --git a/Zend/zend_vm_def.h b/Zend/zend_vm_def.h
index 898bb1229a..3d0fdc0182 100644
--- a/Zend/zend_vm_def.h
+++ b/Zend/zend_vm_def.h
@@ -5045,11 +5045,12 @@ ZEND_VM_HANDLER(99, ZEND_FETCH_CONSTANT, UNUSED|CONST_FETCH, CONST, CACHE_SLOT)
 {
 	USE_OPLINE
 	zend_constant *c;
+	zend_bool is_deprecated;
 
 	c = CACHED_PTR(opline->extended_value);
 	if (EXPECTED(c != NULL) && EXPECTED(!IS_SPECIAL_CACHE_VAL(c))) {
 		/* pass */
-	} else if (UNEXPECTED((c = zend_quick_get_constant(RT_CONSTANT(opline, opline->op2) + 1, opline->op1.num)) == NULL)) {
+	} else if (UNEXPECTED((c = zend_quick_get_constant(RT_CONSTANT(opline, opline->op2) + 1, opline->op1.num, &is_deprecated)) == NULL)) {
 		SAVE_OPLINE();
 
 		if ((opline->op1.num & IS_CONSTANT_UNQUALIFIED) != 0) {
@@ -5070,6 +5071,14 @@ ZEND_VM_HANDLER(99, ZEND_FETCH_CONSTANT, UNUSED|CONST_FETCH, CONST, CACHE_SLOT)
 			ZVAL_UNDEF(EX_VAR(opline->result.var));
 			HANDLE_EXCEPTION();
 		}
+	} else if (is_deprecated) {
+		SAVE_OPLINE();
+		zend_error(E_DEPRECATED,
+			"Case-insensitive constants are deprecated. "
+			"The correct casing for this constant is \"%s\"",
+			ZSTR_VAL(c->name));
+		ZVAL_COPY_OR_DUP(EX_VAR(opline->result.var), &c->value);
+		ZEND_VM_NEXT_OPCODE_CHECK_EXCEPTION();
 	} else {
 		CACHE_PTR(opline->extended_value, c);
 	}
@@ -7611,7 +7620,7 @@ ZEND_VM_HANDLER(122, ZEND_DEFINED, CONST, ANY, CACHE_SLOT)
 				break;
 			}
 		}
-		if ((c = zend_quick_get_constant(RT_CONSTANT(opline, opline->op1), 0)) == NULL) {
+		if ((c = zend_quick_get_constant(RT_CONSTANT(opline, opline->op1), 0, NULL)) == NULL) {
 			CACHE_PTR(opline->extended_value, ENCODE_SPECIAL_CACHE_NUM(zend_hash_num_elements(EG(zend_constants))));
 			result = 0;
 		} else {
diff --git a/Zend/zend_vm_execute.h b/Zend/zend_vm_execute.h
index 499838f1cc..c5598d6da7 100644
--- a/Zend/zend_vm_execute.h
+++ b/Zend/zend_vm_execute.h
@@ -3883,7 +3883,7 @@ static ZEND_OPCODE_HANDLER_RET ZEND_FASTCALL ZEND_DEFINED_SPEC_CONST_HANDLER(ZEN
 				break;
 			}
 		}
-		if ((c = zend_quick_get_constant(RT_CONSTANT(opline, opline->op1), 0)) == NULL) {
+		if ((c = zend_quick_get_constant(RT_CONSTANT(opline, opline->op1), 0, NULL)) == NULL) {
 			CACHE_PTR(opline->extended_value, ENCODE_SPECIAL_CACHE_NUM(zend_hash_num_elements(EG(zend_constants))));
 			result = 0;
 		} else {
@@ -31965,11 +31965,12 @@ static ZEND_OPCODE_HANDLER_RET ZEND_FASTCALL ZEND_FETCH_CONSTANT_SPEC_UNUSED_CON
 {
 	USE_OPLINE
 	zend_constant *c;
+	zend_bool is_deprecated;
 
 	c = CACHED_PTR(opline->extended_value);
 	if (EXPECTED(c != NULL) && EXPECTED(!IS_SPECIAL_CACHE_VAL(c))) {
 		/* pass */
-	} else if (UNEXPECTED((c = zend_quick_get_constant(RT_CONSTANT(opline, opline->op2) + 1, opline->op1.num)) == NULL)) {
+	} else if (UNEXPECTED((c = zend_quick_get_constant(RT_CONSTANT(opline, opline->op2) + 1, opline->op1.num, &is_deprecated)) == NULL)) {
 		SAVE_OPLINE();
 
 		if ((opline->op1.num & IS_CONSTANT_UNQUALIFIED) != 0) {
@@ -31990,6 +31991,14 @@ static ZEND_OPCODE_HANDLER_RET ZEND_FASTCALL ZEND_FETCH_CONSTANT_SPEC_UNUSED_CON
 			ZVAL_UNDEF(EX_VAR(opline->result.var));
 			HANDLE_EXCEPTION();
 		}
+	} else if (is_deprecated) {
+		SAVE_OPLINE();
+		zend_error(E_DEPRECATED,
+			"Case-insensitive constants are deprecated. "
+			"The correct casing for this constant is \"%s\"",
+			ZSTR_VAL(c->name));
+		ZVAL_COPY_OR_DUP(EX_VAR(opline->result.var), &c->value);
+		ZEND_VM_NEXT_OPCODE_CHECK_EXCEPTION();
 	} else {
 		CACHE_PTR(opline->extended_value, c);
 	}