Qt5.QtCreator_屏蔽警告
ZC：注意: 修改了这个配置的话，如果有多个Qt进程的话，它不会自动同步各个进程中的值，可能是 以最后保存的为准（需要注意 ! !）
1、QtCreator屏蔽指定警告 - weixin_40954205的博客 - CSDN博客.html（https://blog.csdn.net/weixin_40954205/article/details/83750864?tdsourcetag=s_pctim_aiomsg）
Tools > Options > C++ > Code Model > Clang Code Model > Manage 创建自己的配置 // ZC: 我是 复制了一份原来的配置“Clang-only checks for almost everything (CopyByZC)”（原来的那个 就是“Clang-only checks for almost everything”）
在Clang中添加要屏蔽的警告, 例如: -Wno-weak-vtables -Wno-old-style-cast 确定后选择应用.
例子
- 对应警告名称为: unused-variable
- 格式为-Wno-警告名称
- -Wno-unused-variable
ZC：我的配置
例如 如下情况：
看到，鼠标放在 空心三角上 有"Deprecations"显示出来，在提示信息的右上角 灰色字"-Wdeprecated-declarations"，然后在 配置中 添加"-Wno-deprecated-declarations"，然后里面的数据就是：
-Weverything -Wno-c++98-compat -Wno-c++98-compat-pedantic -Wno-unused-macros -Wno-newline-eof -Wno-exit-time-destructors -Wno-global-constructors -Wno-gnu-zero-variadic-macro-arguments -Wno-documentation -Wno-shadow -Wno-switch-enum -Wno-missing-prototypes -Wno-used-but-marked-unused -Wno-old-style-cast -Wno-sign-conversion -Wno-deprecated-declarations
2、（20191020）我现在遇到的 Qt598(vs2017)里面的报错 很多很奇怪... 和Qt532(vs2010)比起来 多报了很多东西，如 空心圆 / 空心三角形 的报错和警告，不知道是什么...vs2017_cpp 还没有仔细用，还不知道 是不是 vs2017新增的东西...
但是查到的一些报错信息 像是 苹果里面的报错(∵很多度娘搜索结果 都引向了苹果报错的网页内容...)，难道 微软是想让vs在所有平台上都可以开发？？？走这条路？？（貌似 不是MS是Qt弄的？）
2.1、iOS：消除项目中警告 - 菩提树下苦思 - 博客园.html（https://www.cnblogs.com/XYQ-208910/p/6058652.html?tdsourcetag=s_pctim_aiomsg）
ZC：这是我在 搜索 Qt598(vs2017)里面很多&很烦的 空心圆&空心三角形的报错和警告时 找到的网页内容，它就是 苹果的信息...
2.1.1、网页内容 复制：
↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓ ↓
引言：
在iOS开发过程中, 我们可能会碰到一些系统方法弃用, weak、循环引用、不能执行之类的警告。 有代码洁癖的孩子们很想消除他们, 今天就让我们来一次Fuck 警告！！
首先学会基本的语句：
#pragma clang diagnostic push #pragma clang diagnostic ignored "-Wdeprecated-declarations"
中间这里写出现警告的代码
#pragma clang diagnostic pop
这样就消除了方法弃用的警告！
也即使用如下：
#pragma clang diagnostic push #pragma clang diagnostic ignored "-Wdeprecated-declarations" //这里写出现警告的代码就能实现去除警告(代码写在这中间) #pragma clang diagnostic pop
同理, 大家可以在下边搜索到对应的警告, 这样 就可以把前边的字符串填入上边的ignored的后边, 然后括住你的代码, 就OK了
Semantic Warnings
Warning Message
-WCFString-literal input conversion stopped due to an input byte that does not belong to the input codeset UTF-8
-WNSObject-attribute __attribute ((NSObject)) may be put on a typedef only, attribute is ignored
-Wabstract-vbase-init initializer for virtual base class %0 of abstract class %1 will never be used
-Waddress-of-array-temporary pointer is initialized by a temporary array, which will be destroyed at the end of the full-expression
-Warc-maybe-repeated-use-of-weak "weak %select{variable|property|implicit property|instance variable}0 %1 may be accessed multiple times in this %select{function|method|block|lambda}2 and may be unpredictably set to nil assign to a strong variable to keep the object alive
-Warc-non-pod-memaccess %select{destination for|source of}0 this %1 call is a pointer to ownership-qualified type %2
-Warc-performSelector-leaks performSelector may cause a leak because its selector is unknown
-Warc-repeated-use-of-weak "weak %select{variable|property|implicit property|instance variable}0 %1 is accessed multiple times in this %select{function|method|block|lambda}2 but may be unpredictably set to nil assign to a strong variable to keep the object alive
-Warc-retain-cycles capturing %0 strongly in this block is likely to lead to a retain cycle
-Warc-unsafe-retained-assign assigning retained object to unsafe property object will be released after assignment
-Warc-unsafe-retained-assign assigning %select{array literal|dictionary literal|numeric literal|boxed expression|should not happen|block literal}0 to a weak %select{property|variable}1 object will be released after assignment
-Warc-unsafe-retained-assign assigning retained object to %select{weak|unsafe_unretained}0 %select{property|variable}1 object will be released after assignment
-Warray-bounds array index %0 is past the end of the array (which contains %1 element%s2)
-Warray-bounds array index %0 is before the beginning of the array
-Warray-bounds 'static' has no effect on zero-length arrays
-Warray-bounds array argument is too small contains %0 elements, callee requires at least %1
-Warray-bounds-pointer-arithmetic the pointer incremented by %0 refers past the end of the array (that contains %1 element%s2)
-Warray-bounds-pointer-arithmetic the pointer decremented by %0 refers before the beginning of the array
-Wassign-enum integer constant not in range of enumerated type %0
-Watomic-property-with-user-defined-accessor writable atomic property %0 cannot pair a synthesized %select{getter|setter}1 with a user defined %select{getter|setter}2
-Wattributes unknown attribute %0 ignored
-Wauto-var-id 'auto' deduced as 'id' in declaration of %0
-Wavailability unknown platform %0 in availability macro
-Wavailability overriding method %select{introduced after|deprecated before|obsoleted before}0 overridden method on %1 (%2 vs. %3)
-Wavailability availability does not match previous declaration
-Wavailability overriding method cannot be unavailable on %0 when its overridden method is available
-Wavailability feature cannot be %select{introduced|deprecated|obsoleted}0 in %1 version %2 before it was %select{introduced|deprecated|obsoleted}3 in version %4 attribute ignored
-Wbad-function-cast cast from function call of type %0 to non-matching type %1
-Wbitfield-constant-conversion implicit truncation from %2 to bitfield changes value from %0 to %1
-Wbitwise-op-parentheses '&' within '|'
-Wbool-conversion "initialization of pointer of type %0 to null from a constant boolean " "expression
-Wbridge-cast %0 cannot bridge to %1
-Wbridge-cast %0 bridges to %1, not %2
-Wbuiltin-requires-header declaration of built-in function '%0' requires inclusion of the header stdio.h
-Wbuiltin-requires-header declaration of built-in function '%0' requires inclusion of the header setjmp.h
-Wbuiltin-requires-header declaration of built-in function '%0' requires inclusion of the header ucontext.h
-Wc++-compat %select{|empty }0%select{struct|union}1 has size 0 in C, %select{size 1|non-zero size}2 in C++
-Wc++11-compat explicit instantiation cannot be 'inline'
-Wc++11-compat explicit instantiation of %0 must occur at global scope
-Wc++11-compat explicit instantiation of %0 not in a namespace enclosing %1
-Wc++11-compat explicit instantiation of %q0 must occur in namespace %1
-Wc++11-narrowing constant expression evaluates to %0 which cannot be narrowed to type %1 in C++11
-Wc++11-narrowing type %0 cannot be narrowed to %1 in initializer list in C++11
-Wc++11-narrowing non-constant-expression cannot be narrowed from type %0 to %1 in initializer list in C++11
-Wc++98-c++11-compat type definition in a constexpr %select{function|constructor}0 is incompatible with C++ standards before C++1y
-Wc++98-c++11-compat use of this statement in a constexpr %select{function|constructor}0 is incompatible with C++ standards before C++1y
-Wc++98-c++11-compat init-captures.def warn_cxx11_compat_init_capture : Warning "initialized lambda captures are incompatible with C++ standards " "before C++1y
-Wc++98-c++11-compat variable declaration in a constexpr %select{function|constructor}0 is incompatible with C++ standards before C++1y
-Wc++98-c++11-compat constexpr function with no return statements is incompatible with C++ standards before C++1y
-Wc++98-c++11-compat multiple return statements in constexpr function is incompatible with C++ standards before C++1y
-Wc++98-c++11-compat variable templates are incompatible with C++ standards before C++1y
-Wc++98-compat substitution failure due to access control is incompatible with C++98
-Wc++98-compat %select{anonymous struct|union}0 member %1 with a non-trivial %select{constructor|copy constructor|move constructor|copy assignment operator|move assignment operator|destructor}2 is incompatible with C++98
-Wc++98-compat enumeration type in nested name specifier is incompatible with C++98
-Wc++98-compat static data member %0 in union is incompatible with C++98
-Wc++98-compat default template arguments for a function template are incompatible with C++98
-Wc++98-compat scalar initialized from empty initializer list is incompatible with C++98
-Wc++98-compat befriending %1 without '%select{struct|interface|union|class|enum}0' keyword is incompatible with C++98
-Wc++98-compat use of null pointer as non-type template argument is incompatible with C++98
-Wc++98-compat friend declaration naming a member of the declaring class is incompatible with C++98
-Wc++98-compat non-class friend type %0 is incompatible with C++98
-Wc++98-compat befriending enumeration type %0 is incompatible with C++98
-Wc++98-compat use of non-static data member %0 in an unevaluated context is incompatible with C++98
-Wc++98-compat friend function %0 would be implicitly redefined in C++98
-Wc++98-compat %select{class template|class template partial|variable template|variable template partial|function template|member function|static data member|member class|member enumeration}0 specialization of %1 outside namespace %2 is incompatible with C++98
-Wc++98-compat reference initialized from initializer list is incompatible with C++98
-Wc++98-compat redundant parentheses surrounding address non-type template argument are incompatible with C++98
-Wc++98-compat initialization of initializer_list object is incompatible with C++98
-Wc++98-compat use of 'template' keyword outside of a template is incompatible with C++98
-Wc++98-compat non-type template argument referring to %select{function|object}0 %1 with internal linkage is incompatible with C++98
-Wc++98-compat use of 'typename' outside of a template is incompatible with C++98
-Wc++98-compat passing object of trivial but non-POD type %0 through variadic %select{function|block|method|constructor}1 is incompatible with C++98
-Wc++98-compat goto would jump into protected scope in C++98
-Wc++98-compat constructor call from initializer list is incompatible with C++98
-Wc++98-compat 'auto' type specifier is incompatible with C++98
-Wc++98-compat delegating constructors are incompatible with C++98
-Wc++98-compat 'constexpr' specifier is incompatible with C++98
-Wc++98-compat inheriting constructors are incompatible with C++98
-Wc++98-compat explicit conversion functions are incompatible with C++98
-Wc++98-compat switch case would be in a protected scope in C++98
-Wc++98-compat '%0' type specifier is incompatible with C++98
-Wc++98-compat indirect goto might cross protected scopes in C++98
-Wc++98-compat-pedantic cast between pointer-to-function and pointer-to-object is incompatible with C++98
-Wc++98-compat-pedantic implicit conversion from array size expression of type %0 to %select{integral|enumeration}1 type %2 is incompatible with C++98
-Wcast-align cast from %0 to %1 increases required alignment from %2 to %3
-Wcast-of-sel-type cast of type %0 to %1 is deprecated use sel_getName instead
-Wchar-subscripts array subscript is of type 'char'
-Wconditional-uninitialized variable %0 may be uninitialized when %select{used here|captured by block}1
-Wconstant-logical-operand use of logical '%0' with constant operand
-Wconstexpr-not-const 'constexpr' non-static member function will not be implicitly 'const' in C++1y add 'const' to avoid a change in behavior
-Wconsumed state of variable '%0' must match at the entry and exit of loop
-Wconsumed parameter '%0' not in expected state when the function returns: expected '%1', observed '%2'
-Wconsumed argument not in expected state expected '%0', observed '%1'
-Wconsumed invalid invocation of method '%0' on a temporary object while it is in the '%1' state
-Wconsumed return state set for an unconsumable type '%0'
-Wconsumed consumed analysis attribute is attached to member of class '%0' which isn't marked as consumable
-Wconsumed invalid invocation of method '%0' on object '%1' while it is in the '%2' state
-Wconsumed return value not in expected state expected '%0', observed '%1'
-Wconversion implicit conversion discards imaginary component: %0 to %1
-Wconversion non-type template argument with value '%0' converted to '%1' for unsigned template parameter of type %2
-Wconversion implicit conversion loses floating-point precision: %0 to %1
-Wconversion implicit conversion loses integer precision: %0 to %1
-Wconversion non-type template argument value '%0' truncated to '%1' for template parameter of type %2
-Wconversion implicit conversion turns vector to scalar: %0 to %1
-Wconversion implicit conversion turns floating-point number into integer: %0 to %1
-Wcovered-switch-default default label in switch which covers all enumeration values
-Wcustom-atomic-properties atomic by default property %0 has a user defined %select{getter|setter}1 (property should be marked 'atomic' if this is intended)
-Wdangling-field initializing pointer member %0 with the stack address of parameter %1
-Wdangling-field binding reference %select{|subobject of }1member %0 to a temporary value
-Wdangling-field binding reference member %0 to stack allocated parameter %1
-Wdangling-initializer-list array backing the initializer list will be destroyed at the end of %select{the full-expression|the constructor}0
-Wdelete-incomplete deleting pointer to incomplete type %0 may cause undefined behavior
-Wdelete-non-virtual-dtor delete called on %0 that is abstract but has non-virtual destructor
-Wdelete-non-virtual-dtor delete called on %0 that has virtual functions but non-virtual destructor
-Wdeprecated access declarations are deprecated use using declarations instead
-Wdeprecated definition of implicit copy %select{constructor|assignment operator}1 for %0 is deprecated because it has a user-declared %select{copy %select{assignment operator|constructor}1|destructor}2
-Wdeprecated dynamic exception specifications are deprecated
-Wdeprecated-increment-bool incrementing expression of type bool is deprecated
-Wdeprecated-objc-isa-usage assignment to Objective-C's isa is deprecated in favor of object_setClass()
-Wdeprecated-objc-isa-usage direct access to Objective-C's isa is deprecated in favor of object_getClass()
-Wdeprecated-objc-pointer-introspection bitmasking for introspection of Objective-C object pointers is strongly discouraged
-Wdeprecated-objc-pointer-introspection-performSelector warn_objc_pointer_masking.Text
-Wdeprecated-writable-strings dummy warning to enable -fconst-strings
-Wdirect-ivar-access instance variable %0 is being directly accessed
-Wdistributed-object-modifiers conflicting distributed object modifiers on return type in implementation of %0
-Wdistributed-object-modifiers conflicting distributed object modifiers on parameter type in implementation of %0
-Wdivision-by-zero division by zero is undefined
-Wdivision-by-zero remainder by zero is undefined
-Wdocumentation parameter '%0' not found in the function declaration
-Wdocumentation not a Doxygen trailing comment
-Wduplicate-enum element %0 has been implicitly assigned %1 which another element has been assigned
-Wduplicate-method-match multiple declarations of method %0 found and ignored
-Wdynamic-class-memaccess %select{destination for|source of|first operand of|second operand of}0 this %1 call is a pointer to dynamic class %2 vtable pointer will be %select{overwritten|copied|moved|compared}3
-Wempty-body switch statement has empty body
-Wempty-body for loop has empty body
-Wempty-body if statement has empty body
-Wempty-body range-based for loop has empty body
-Wempty-body while loop has empty body
-Wenum-compare comparison of two values with different enumeration types%diff{ ($ and $)|}0,1
-Wenum-conversion implicit conversion from enumeration type %0 to different enumeration type %1
-Wexit-time-destructors declaration requires an exit-time destructor
-Wexplicit-ownership-type method parameter of type %0 with no explicit ownership
-Wextern-c-compat %select{|empty }0%select{struct|union}1 has size 0 in C, %select{size 1|non-zero size}2 in C++
-Wextern-initializer 'extern' variable has an initializer
-Wfloat-equal comparing floating point with == or != is unsafe
-Wformat "data argument position '%0' exceeds the number of data arguments (%1)
-Wformat position arguments in format strings start counting at 1 (not 0)
-Wformat invalid position specified for %select{field width|field precision}0
-Wformat cannot mix positional and non-positional arguments in format string
-Wformat values of type '%0' should not be used as format arguments add an explicit cast to %1 instead
-Wformat format specifies type %0 but the argument has type %1
-Wformat zero field width in scanf format string is unused
-Wformat no closing ']' for '%%[' in scanf format string
-Wformat format string should not be a wide string
-Wformat format string contains '\\0' within the string body
-Wformat '%select{*|.*}0' specified field %select{width|precision}0 is missing a matching 'int' argument
-Wformat field %select{width|precision}0 should have type %1, but argument has type %2
-Wformat %select{field width|precision}0 used with '%1' conversion specifier, resulting in undefined behavior
-Wformat format string missing
-Wformat incomplete format specifier
-Wformat flag '%0' results in undefined behavior with '%1' conversion specifier
-Wformat flag '%0' is ignored when flag '%1' is present
-Wformat more '%%' conversions than data arguments
-Wformat length modifier '%0' results in undefined behavior or no effect with '%1' conversion specifier
-Wformat-extra-args data argument not used by format string
-Wformat-invalid-specifier invalid conversion specifier '%0'
-Wformat-nonliteral format string is not a string literal
-Wformat-security format string is not a string literal (potentially insecure)
-Wformat-zero-length format string is empty
-Wgcc-compat GCC does not allow the 'cleanup' attribute argument to be anything other than a simple identifier
-Wglobal-constructors declaration requires a global constructor
-Wglobal-constructors declaration requires a global destructor
-Wgnu-conditional-omitted-operand use of GNU ?: conditional expression extension, omitting middle operand
-Wheader-hygiene using namespace directive in global context in header
-Widiomatic-parentheses using the result of an assignment as a condition without parentheses
-Wignored-attributes 'malloc' attribute only applies to functions returning a pointer type
-Wignored-attributes %0 attribute only applies to %select{functions|unions|variables and functions|functions and methods|parameters|functions, methods and blocks|functions, methods, and classes|functions, methods, and parameters|classes|variables|methods|variables, functions and labels|fields and global variables|structs|variables, functions and tag types|thread-local variables|variables and fields|variables, data members and tag types|types and namespaces|Objective-C interfaces}1
-Wignored-attributes '%0' attribute cannot be specified on a definition
-Wignored-attributes __weak attribute cannot be specified on an automatic variable when ARC is not enabled
-Wignored-attributes Objective-C GC does not allow weak variables on the stack
-Wignored-attributes __weak attribute cannot be specified on a field declaration
-Wignored-attributes attribute %0 cannot be applied to %select{functions|Objective-C method}1 without return value
-Wignored-attributes attribute declaration must precede definition
-Wignored-attributes attribute %0 is ignored, place it after \"%select{class|struct|union|interface|enum}1\" to apply attribute to type declaration
-Wignored-attributes __declspec attribute %0 is not supported
-Wignored-attributes attribute %0 ignored, because it cannot be applied to a type
-Wignored-attributes attribute %0 after definition is ignored
-Wignored-attributes %0 attribute ignored
-Wignored-attributes 'sentinel' attribute only supported for variadic %select{functions|blocks}0
-Wignored-attributes 'sentinel' attribute requires named arguments
-Wignored-attributes '%0' only applies to %select{function|pointer|Objective-C object or block pointer}1 types type here is %2
-Wignored-attributes 'nonnull' attribute applied to function with no pointer arguments
-Wignored-attributes %0 attribute can only be applied to instance variables or properties
-Wignored-attributes ibaction attribute can only be applied to Objective-C instance methods
-Wignored-attributes %0 calling convention ignored on variadic function
-Wignored-attributes %0 only applies to variables with static storage duration and functions
-Wignored-attributes %0 attribute argument not supported: %1
-Wignored-attributes #pramga ms_struct can not be used with dynamic classes or structures
-Wignored-attributes transparent union definition must contain at least one field transparent_union attribute ignored
-Wignored-attributes first field of a transparent union cannot have %select{floating point|vector}0 type %1 transparent_union attribute ignored
-Wignored-attributes 'gnu_inline' attribute requires function to be marked 'inline', attribute ignored
-Wignored-attributes calling convention %0 ignored for this target
-Wignored-attributes transparent_union attribute can only be applied to a union definition attribute ignored
-Wignored-attributes %select{alignment|size}0 of field %1 (%2 bits) does not match the %select{alignment|size}0 of the first field in transparent union transparent_union attribute ignored
-Wignored-attributes attribute %0 is already applied
-Wignored-attributes %0 attribute ignored for field of type %1
-Wignored-attributes %0 attribute ignored when parsing type
-Wignored-attributes %0 attribute only applies to %select{functions|methods|properties}1 that return %select{an Objective-C object|a pointer|a non-retainable pointer}2
-Wignored-attributes %0 attribute only applies to %select{Objective-C object|pointer}1 parameters
-Wignored-attributes attribute %0 is already applied with different parameters
-Wignored-attributes unknown visibility %0
-Wignored-qualifiers "'%0' type qualifier%s1 on return type %plural{1:has|:have}1 no effect
-Wignored-qualifiers ARC %select{unused|__unsafe_unretained|__strong|__weak|__autoreleasing}0 lifetime qualifier on return type is ignored
-Wimplicit-atomic-properties property is assumed atomic by default
-Wimplicit-atomic-properties property is assumed atomic when auto-synthesizing the property
-Wimplicit-fallthrough fallthrough annotation in unreachable code
-Wimplicit-fallthrough unannotated fall-through between switch labels
-Wimplicit-fallthrough fallthrough annotation does not directly precede switch label
-Wimplicit-function-declaration implicit declaration of function %0
-Wimplicit-function-declaration use of unknown builtin %0
-Wimplicit-retain-self "block implicitly retains 'self' explicitly mention 'self' to indicate this is intended behavior
-Wincompatible-library-redeclaration incompatible redeclaration of library function %0
-Wincomplete-implementation method definition for %0 not found
-Winherited-variadic-ctor inheriting constructor does not inherit ellipsis
-Winitializer-overrides subobject initialization overrides initialization of other fields within its enclosing subobject
-Winitializer-overrides initializer overrides prior initialization of this subobject
-Wint-to-pointer-cast cast to %1 from smaller integer type %0
-Wint-to-void-pointer-cast cast to %1 from smaller integer type %0
-Winvalid-iboutlet IBOutletCollection properties should be copy/strong and not assign
-Winvalid-iboutlet %select{instance variable|property}2 with %0 attribute must be an object type (invalid %1)
-Winvalid-noreturn function %0 declared 'noreturn' should not return
-Winvalid-noreturn function declared 'noreturn' should not return
-Wlarge-by-value-copy return value of %0 is a large (%1 bytes) pass-by-value object pass it by reference instead ?
-Wlarge-by-value-copy %0 is a large (%1 bytes) pass-by-value argument pass it by reference instead ?
-Wliteral-conversion implicit conversion from %0 to %1 changes value from %2 to %3
-Wliteral-range magnitude of floating-point constant too large for type %0 maximum is %1
-Wliteral-range magnitude of floating-point constant too small for type %0 minimum is %1
-Wlogical-not-parentheses logical not is only applied to the left hand side of this comparison
-Wlogical-op-parentheses '&&' within '||'
-Wloop-analysis variable%select{s| %1|s %1 and %2|s %1, %2, and %3|s %1, %2, %3, and %4}0 used in loop condition not modified in loop body
-Wloop-analysis variable %0 is %select{decremented|incremented}1 both in the loop header and in the loop body
-Wmethod-signatures conflicting parameter types in implementation of %0: %1 vs %2
-Wmethod-signatures conflicting return type in implementation of %0: %1 vs %2
-Wmicrosoft extra qualification on member %0
-Wmismatched-method-attributes attributes on method implementation and its declaration must match
-Wmismatched-parameter-types conflicting parameter types in implementation of %0%diff{: $ vs $|}1,2
-Wmismatched-return-types conflicting return type in implementation of %0%diff{: $ vs $|}1,2
-Wmissing-braces suggest braces around initialization of subobject
-Wmissing-declarations '%0' ignored on this declaration
-Wmissing-field-initializers missing field '%0' initializer
-Wmissing-method-return-type method has no return type specified defaults to 'id'
-Wmissing-noreturn %select{function|method}0 %1 could be declared with attribute 'noreturn'
-Wmissing-noreturn block could be declared with attribute 'noreturn'
-Wmissing-prototypes no previous prototype for function %0
-Wmissing-variable-declarations no previous extern declaration for non-static variable %0
-Wmultiple-move-vbase defaulted move assignment operator of %0 will move assign virtual base class %1 multiple times
-Wnested-anon-types anonymous types declared in an anonymous union/struct are an extension
-Wno-typedef-redefinition Redefinition of typedef '%0' is a C11 feature
-Wnon-literal-null-conversion "expression which evaluates to zero treated as a null pointer constant of " "type %0
-Wnon-pod-varargs second argument to 'va_arg' is of ARC ownership-qualified type %0
-Wnon-pod-varargs cannot pass %select{non-POD|non-trivial}0 object of type %1 to variadic %select{function|block|method|constructor}2 expected type from format string was %3
-Wnon-pod-varargs second argument to 'va_arg' is of non-POD type %0
-Wnon-pod-varargs cannot pass object of %select{non-POD|non-trivial}0 type %1 through variadic %select{function|block|method|constructor}2 call will abort at runtime
-Wnon-virtual-dtor %0 has virtual functions but non-virtual destructor
-Wnonnull null passed to a callee which requires a non-null argument
-Wnull-arithmetic use of NULL in arithmetic operation
-Wnull-arithmetic comparison between NULL and non-pointer %select{(%1 and NULL)|(NULL and %1)}0
-Wnull-dereference indirection of non-volatile null pointer will be deleted, not trap
-Wobjc-autosynthesis-property-ivar-name-match autosynthesized property %0 will use %select{|synthesized}1 instance variable %2, not existing instance variable %3
-Wobjc-forward-class-redefinition redefinition of forward class %0 of a typedef name of an object type is ignored
-Wobjc-interface-ivars declaration of instance variables in the interface is deprecated
-Wobjc-literal-compare direct comparison of %select{an array literal|a dictionary literal|a numeric literal|a boxed expression|}0 has undefined behavior
-Wobjc-literal-missing-atsign string literal must be prefixed by '@'
-Wobjc-method-access instance method %objcinstance0 not found (return type defaults to 'id') did you mean %objcinstance2?
-Wobjc-method-access class method %objcclass0 not found (return type defaults to 'id') did you mean %objcclass2?
-Wobjc-method-access instance method %objcinstance0 not found (return type defaults to 'id')
-Wobjc-method-access instance method %0 is being used on 'Class' which is not in the root class
-Wobjc-method-access class method %objcclass0 not found (return type defaults to 'id')
-Wobjc-method-access instance method %0 found instead of class method %1
-Wobjc-missing-property-synthesis "auto property synthesis is synthesizing property not explicitly synthesized
-Wobjc-missing-super-calls method possibly missing a [super %0] call
-Wobjc-noncopy-retain-block-property "retain'ed block property does not copy the block " "- use copy attribute instead
-Wobjc-nonunified-exceptions can not catch an exception thrown with @throw in C++ in the non-unified exception model
-Wobjc-property-implementation property %0 requires method %1 to be defined - use @dynamic or provide a method implementation in this category
-Wobjc-property-implementation property %0 requires method %1 to be defined - use @synthesize, @dynamic or provide a method implementation in this class implementation
-Wobjc-property-implicit-mismatch "primary property declaration is implicitly strong while redeclaration in class extension is weak
-Wobjc-property-matches-cocoa-ownership-rule property's synthesized getter follows Cocoa naming convention for returning 'owned' objects
-Wobjc-property-no-attribute no 'assign', 'retain', or 'copy' attribute is specified - 'assign' is assumed
-Wobjc-property-no-attribute default property attribute 'assign' not appropriate for non-GC object
-Wobjc-property-synthesis auto property synthesis will not synthesize property '%0' because it is 'readwrite' but it will be synthesized 'readonly' via another property
-Wobjc-property-synthesis "auto property synthesis will not synthesize property '%0' because it cannot share an ivar with another synthesized property
-Wobjc-protocol-method-implementation category is implementing a method which will also be implemented by its primary class
-Wobjc-protocol-property-synthesis auto property synthesis will not synthesize property declared in a protocol
-Wobjc-redundant-literal-use using %0 with a literal is redundant
-Wobjc-root-class class %0 defined without specifying a base class
-Wobjc-string-compare direct comparison of a string literal has undefined behavior
-Wobjc-string-concatenation concatenated NSString literal for an NSArray expression - possibly missing a comma
-Wover-aligned type %0 requires %1 bytes of alignment and the default allocator only guarantees %2 bytes
-Woverloaded-shift-op-parentheses overloaded operator %select{|}0 has lower precedence than comparison operator
-Woverloaded-virtual %q0 hides overloaded virtual %select{function|functions}1
-Woverriding-method-mismatch conflicting distributed object modifiers on parameter type in declaration of %0
-Woverriding-method-mismatch conflicting parameter types in declaration of %0: %1 vs %2
-Woverriding-method-mismatch conflicting variadic declaration of method and its implementation
-Woverriding-method-mismatch conflicting distributed object modifiers on return type in declaration of %0
-Woverriding-method-mismatch conflicting parameter types in declaration of %0%diff{: $ vs $|}1,2
-Woverriding-method-mismatch conflicting return type in declaration of %0%diff{: $ vs $|}1,2
-Woverriding-method-mismatch conflicting return type in declaration of %0: %1 vs %2
-Wpacked packed attribute is unnecessary for %0
-Wpadded padding %select{struct|interface|class}0 %1 with %2 %select{byte|bit}3%select{|s}4 to align anonymous bit-field
-Wpadded padding %select{struct|interface|class}0 %1 with %2 %select{byte|bit}3%select{|s}4 to align %5
-Wpadded padding size of %0 with %1 %select{byte|bit}2%select{|s}3 to alignment boundary
-Wparentheses using the result of an assignment as a condition without parentheses
-Wparentheses %0 has lower precedence than %1 %1 will be evaluated first
-Wparentheses operator '?:' has lower precedence than '%0' '%0' will be evaluated first
-Wparentheses-equality equality comparison with extraneous parentheses
-Wpointer-arith subtraction of pointers to type %0 of zero size has undefined behavior
-Wpredefined-identifier-outside-function predefined identifier is only valid inside function
-Wprivate-extern use of __private_extern__ on a declaration may not produce external symbol private to the linkage unit and is deprecated
-Wprotocol method %0 in protocol not implemented
-Wprotocol-property-synthesis-ambiguity property of type %0 was selected for synthesis
-Wreadonly-iboutlet-property readonly IBOutlet property '%0' when auto-synthesized may not work correctly with 'nib' loader
-Wreadonly-setter-attrs property attributes '%0' and '%1' are mutually exclusive
-Wreceiver-expr receiver type %0 is not 'id' or interface pointer, consider casting it to 'id'
-Wreceiver-forward-class receiver type %0 for instance message is a forward declaration
-Wreceiver-is-weak "weak %select{receiver|property|implicit property}0 may be unpredictably set to nil
-Wreinterpret-base-class 'reinterpret_cast' %select{from|to}3 class %0 %select{to|from}3 its %select{virtual base|base at non-zero offset}2 %1 behaves differently from 'static_cast'
-Wreorder %select{field|base class}0 %1 will be initialized after %select{field|base}2 %3
-Wrequires-super-attribute %0 attribute cannot be applied to %select{methods in protocols|dealloc}1
-Wreturn-stack-address returning address of local temporary object
-Wreturn-stack-address returning address of label, which is local
-Wreturn-stack-address address of stack memory associated with local variable %0 returned
-Wreturn-stack-address reference to stack memory associated with local variable %0 returned
-Wreturn-stack-address returning reference to local temporary object
-Wreturn-type control may reach end of non-void function
-Wreturn-type non-void %select{function|method}1 %0 should return a value, DefaultError
-Wreturn-type control reaches end of non-void function
-Wreturn-type-c-linkage %0 has C-linkage specified, but returns incomplete type %1 which could be incompatible with C
-Wreturn-type-c-linkage %0 has C-linkage specified, but returns user-defined type %1 which is incompatible with C
-Wsection section does not match previous declaration
-Wselector creating selector for nonexistent method %0
-Wselector-type-mismatch multiple selectors named %0 found
-Wself-assign explicitly assigning a variable of type %0 to itself
-Wself-assign-field assigning %select{field|instance variable}0 to itself
-Wsentinel "missing sentinel in %select{function call|method dispatch|block call}0
-Wsentinel not enough variable arguments in %0 declaration to fit a sentinel
-Wshadow declaration shadows a %select{" "local variable|" "variable in %2|" "static data member of %2|" "field of %2}1
-Wshadow-ivar local declaration of %0 hides instance variable
-Wshift-count-negative shift count is negative
-Wshift-count-overflow shift count = width of type
-Wshift-op-parentheses operator '%0' has lower precedence than '%1' '%1' will be evaluated first
-Wshift-overflow signed shift result (%0) requires %1 bits to represent, but %2 only has %3 bits
-Wshift-sign-overflow signed shift result (%0) sets the sign bit of the shift expression's type (%1) and becomes negative
-Wshorten-64-to-32 implicit conversion loses integer precision: %0 to %1
-Wsign-compare comparison of integers of different signs: %0 and %1
-Wsign-conversion implicit conversion changes signedness: %0 to %1
-Wsign-conversion operand of ? changes signedness: %0 to %1
-Wsizeof-array-argument sizeof on array function parameter will return size of %0 instead of %1
-Wsizeof-array-decay sizeof on pointer operation will return size of %0 instead of %1
-Wsizeof-pointer-memaccess '%0' call operates on objects of type %1 while the size is based on a " "different type %2
-Wsizeof-pointer-memaccess argument to 'sizeof' in %0 call is the same pointer type %1 as the %select{destination|source}2 expected %3 or an explicit length
-Wsometimes-uninitialized variable %0 is %select{used|captured}1 uninitialized whenever %select{'%3' condition is %select{true|false}4|'%3' loop %select{is entered|exits because its condition is false}4|'%3' loop %select{condition is true|exits because its condition is false}4|switch %3 is taken|its declaration is reached|%3 is called}2
-Wstatic-local-in-inline non-constant static local variable in inline function may be different in different files
-Wstatic-self-init static variable %0 is suspiciously used within its own initialization
-Wstrict-selector-match multiple methods named %0 found
-Wstring-compare result of comparison against %select{a string literal|@encode}0 is unspecified (use strncmp instead)
-Wstring-conversion implicit conversion turns string literal into bool: %0 to %1
-Wstring-plus-char adding %0 to a string pointer does not append to the string
-Wstring-plus-int adding %0 to a string does not append to the string
-Wstrlcpy-strlcat-size size argument in %0 call appears to be size of the source expected the size of the destination
-Wstrncat-size the value of the size argument in 'strncat' is too large, might lead to a " "buffer overflow
-Wstrncat-size size argument in 'strncat' call appears " "to be size of the source
-Wstrncat-size the value of the size argument to 'strncat' is wrong
-Wsuper-class-method-mismatch method parameter type %diff{$ does not match super class method parameter type $|does not match super class method parameter type}0,1
-Wswitch overflow converting case value to switch condition type (%0 to %1)
-Wswitch case value not in enumerated type %0
-Wswitch %0 enumeration values not handled in switch: %1, %2, %3...
-Wswitch enumeration values %0 and %1 not handled in switch
-Wswitch enumeration value %0 not handled in switch
-Wswitch enumeration values %0, %1, and %2 not handled in switch
-Wswitch-enum enumeration values %0, %1, and %2 not explicitly handled in switch
-Wswitch-enum enumeration values %0 and %1 not explicitly handled in switch
-Wswitch-enum %0 enumeration values not explicitly handled in switch: %1, %2, %3...
-Wswitch-enum enumeration value %0 not explicitly handled in switch
-Wtautological-compare comparison of %0 unsigned%select{| enum}2 expression is always %1
-Wtautological-compare %select{self-|array }0comparison always evaluates to %select{false|true|a constant}1
-Wtautological-compare comparison of unsigned%select{| enum}2 expression %0 is always %1
-Wtautological-constant-out-of-range-compare comparison of constant %0 with expression of type %1 is always %select{false|true}2
-Wthread-safety-analysis locking '%0' that is already locked
-Wthread-safety-analysis cannot call function '%0' while mutex '%1' is locked
-Wthread-safety-analysis %select{reading|writing}2 the value pointed to by '%0' requires locking %select{'%1'|'%1' exclusively}2
-Wthread-safety-analysis unlocking '%0' that was not locked
-Wthread-safety-analysis mutex '%0' is locked exclusively and shared in the same scope
-Wthread-safety-analysis calling function '%0' requires %select{shared|exclusive}2 lock on '%1'
-Wthread-safety-analysis %select{reading|writing}2 variable '%0' requires locking %select{'%1'|'%1' exclusively}2
-Wthread-safety-analysis cannot resolve lock expression
-Wthread-safety-analysis expecting mutex '%0' to be locked at the end of function
-Wthread-safety-analysis mutex '%0' is not locked on every path through here
-Wthread-safety-analysis %select{reading|writing}1 the value pointed to by '%0' requires locking %select{any mutex|any mutex exclusively}1
-Wthread-safety-analysis %select{reading|writing}1 variable '%0' requires locking %select{any mutex|any mutex exclusively}1
-Wthread-safety-analysis mutex '%0' is still locked at the end of function
-Wthread-safety-analysis expecting mutex '%0' to be locked at start of each loop
-Wthread-safety-attributes ignoring %0 attribute because its argument is invalid
-Wthread-safety-attributes %0 attribute only applies to %select{fields and global variables|functions and methods|classes and structs}1
-Wthread-safety-attributes %0 attribute requires arguments that are class type or point to class type type here is '%1'
-Wthread-safety-attributes %0 attribute can only be applied in a context annotated with 'lockable' attribute
-Wthread-safety-attributes %0 attribute requires arguments whose type is annotated with 'lockable' attribute type here is '%1'
-Wthread-safety-attributes '%0' only applies to pointer types type here is %1
-Wthread-safety-beta Thread safety beta warning.
-Wthread-safety-precise %select{reading|writing}2 the value pointed to by '%0' requires locking %select{'%1'|'%1' exclusively}2
-Wthread-safety-precise %select{reading|writing}2 variable '%0' requires locking %select{'%1'|'%1' exclusively}2
-Wthread-safety-precise calling function '%0' requires %select{shared|exclusive}2 lock on '%1'
-Wtype-safety this type tag was not designed to be used with this function
-Wtype-safety specified %0 type tag requires a null pointer
-Wtype-safety argument type %0 doesn't match specified '%1' type tag %select{that requires %3|}2
-Wundeclared-selector undeclared selector %0 did you mean %1?
-Wundeclared-selector undeclared selector %0
-Wundefined-inline inline function %q0 is not defined
-Wundefined-internal %select{function|variable}0 %q1 has internal linkage but is not defined
-Wundefined-reinterpret-cast dereference of type %1 that was reinterpret_cast from type %0 has undefined behavior
-Wundefined-reinterpret-cast reinterpret_cast from %0 to %1 has undefined behavior
-Wuninitialized reference %0 is not yet bound to a value when used within its own initialization
-Wuninitialized field %0 is uninitialized when used here
-Wuninitialized block pointer variable %0 is uninitialized when captured by block
-Wuninitialized variable %0 is uninitialized when used within its own initialization
-Wuninitialized variable %0 is uninitialized when %select{used here|captured by block}1
-Wuninitialized reference %0 is not yet bound to a value when used here
-Wunneeded-internal-declaration %select{function|variable}0 %1 is not needed and will not be emitted
-Wunneeded-internal-declaration 'static' function %0 declared in header file should be declared 'static inline'
-Wunneeded-member-function member function %0 is not needed and will not be emitted
-Wunreachable-code will never be executed
-Wunsequenced multiple unsequenced modifications to %0
-Wunsequenced unsequenced modification and access to %0
-Wunsupported-friend dependent nested name specifier '%0' for friend template declaration is not supported ignoring this friend declaration
-Wunsupported-friend dependent nested name specifier '%0' for friend class declaration is not supported turning off access control for %1
-Wunsupported-visibility target does not support 'protected' visibility using 'default'
-Wunused-comparison %select{equality|inequality}0 comparison result unused
-Wunused-const-variable unused variable %0
-Wunused-exception-parameter unused exception parameter %0
-Wunused-function unused function %0
-Wunused-label unused label %0
-Wunused-member-function unused member function %0
-Wunused-parameter unused parameter %0
-Wunused-private-field private field %0 is not used
-Wunused-property-ivar ivar %0 which backs the property is not referenced in this property's accessor
-Wunused-result ignoring return value of function declared with warn_unused_result attribute
-Wunused-value ignoring return value of function declared with %0 attribute
-Wunused-value expression result unused should this cast be to 'void'?
-Wunused-value expression result unused
-Wunused-variable unused variable %0
-Wunused-volatile-lvalue expression result unused assign into a variable to force a volatile load
-Wused-but-marked-unused %0 was marked unused but was used
-Wuser-defined-literals user-defined literal suffixes not starting with '_' are reserved%select{ no literal will invoke this operator|}0
-Wvarargs second parameter of 'va_start' not last named argument
-Wvarargs 'va_start' has undefined behavior with reference types
-Wvarargs second argument to 'va_arg' is of promotable type %0 this va_arg has undefined behavior because arguments will be promoted to %1
-Wvector-conversion incompatible vector types %select{%diff{assigning to $ from $|assigning to different types}0,1|%diff{passing $ to parameter of type $|passing to parameter of different type}0,1|%diff{returning $ from a function with result type $|returning from function with different return type}0,1|%diff{converting $ to type $|converting between types}0,1|%diff{initializing $ with an expression of type $|initializing with expression of different type}0,1|%diff{sending $ to parameter of type $|sending to parameter of different type}0,1|%diff{casting $ to type $|casting between types}0,1}2
-Wvexing-parse parentheses were disambiguated as a function declaration
-Wvexing-parse empty parentheses interpreted as a function declaration
-Wvisibility declaration of %0 will not be visible outside of this function
-Wvisibility redefinition of %0 will not be visible outside of this function
-Wvla variable length array used
-Wvla-extension variable length arrays are a C99 feature
-Wweak-template-vtables explicit template instantiation %0 will emit a vtable in every translation unit
-Wweak-vtables %0 has no out-of-line virtual method definitions; its vtable will be emitted in every translation unit
Lexer Warnings
Warning Message
-W#pragma-messages %0
-W#warnings %0
-W#warnings %0
-Wambiguous-macro ambiguous expansion of macro %0
-Wauto-import treating #%select{include|import|include_next|__include_macros}0 as an import of module '%1'
-Wbackslash-newline-escape backslash and newline separated by space
-Wc++11-compat identifier after literal will be treated as a user-defined literal suffix in C++11
-Wc++11-compat '%0' is a keyword in C++11
-Wc++98-c++11-compat digit separators are incompatible with C++ standards before C++1y
-Wc++98-c++11-compat-pedantic binary integer literals are incompatible with C++ standards before C++1y
-Wc++98-compat raw string literals are incompatible with C++98
-Wc++98-compat unicode literals are incompatible with C++98
-Wc++98-compat universal character name referring to a control character is incompatible with C++98
-Wc++98-compat '::' is treated as digraph ':' (aka '[') followed by ':' in C++98
-Wc++98-compat using this character in an identifier is incompatible with C++98
-Wc++98-compat specifying character '%0' with a universal character name is incompatible with C++98
-Wc++98-compat-pedantic variadic macros are incompatible with C++98
-Wc++98-compat-pedantic #line number greater than 32767 is incompatible with C++98
-Wc++98-compat-pedantic C++98 requires newline at end of file
-Wc++98-compat-pedantic empty macro arguments are incompatible with C++98
-Wc99-compat unicode literals are incompatible with C99
-Wc99-compat %select{using this character in an identifier|starting an identifier with this character}0 is incompatible with C99
-Wcomment '/*' within block comment
-Wcomment escaped newline between */ characters at block comment end
-Wdisabled-macro-expansion disabled expansion of recursive macro
-Wheader-guard %0 is used as a header guard here, followed by #define of a different macro
-Wignored-attributes unknown attribute '%0'
-Wincomplete-module header '%0' is included in module '%1' but not listed in module map
-Wincomplete-umbrella umbrella header for module '%0' does not include header '%1'
-Winvalid-token-paste pasting formed '%0', an invalid preprocessing token, DefaultError
-Wmalformed-warning-check __has_warning expected option name (e.g. \"-Wundef\")
-Wnewline-eof no newline at end of file
-Wnull-character null character ignored
-Wnull-character null character(s) preserved in string literal
-Wnull-character null character(s) preserved in character literal
-Wtrigraphs ignored trigraph would end block comment
-Wtrigraphs trigraph ignored
-Wundef %0 is not defined, evaluates to 0
-Wunicode universal character names are only valid in C99 or C++ treating as '\\' followed by identifier
-Wunicode \\%0 used with no following hex digits treating as '\\' followed by identifier
-Wunicode incomplete universal character name treating as '\\' followed by identifier
-Wunicode universal character name refers to a surrogate character
-Wunknown-pragmas unknown pragma ignored
-Wunknown-pragmas pragma STDC FENV_ACCESS ON is not supported, ignoring pragma
-Wunused-macros macro is not used
Parser Warnings
Warning Message
-Warc-bridge-casts-disallowed-in-nonarc '%0' casts have no effect when not using ARC
-Wattributes unknown __declspec attribute %0 ignored
-Wavailability 'unavailable' availability overrides all other availability information
-Wc++11-compat use of right-shift operator ('') in template argument will require parentheses in C++11
-Wc++11-compat 'auto' storage class specifier is redundant and incompatible with C++11
-Wc++98-c++11-compat 'decltype(auto)' type specifier is incompatible with C++ standards before C++1y
-Wc++98-compat range-based for loop is incompatible with C++98
-Wc++98-compat alias declarations are incompatible with C++98
-Wc++98-compat in-class initialization of non-static data members is incompatible with C++98
-Wc++98-compat defaulted function definitions are incompatible with C++98
-Wc++98-compat rvalue references are incompatible with C++98
-Wc++98-compat reference qualifiers on functions are incompatible with C++98
-Wc++98-compat inline namespaces are incompatible with C++98
-Wc++98-compat generalized initializer lists are incompatible with C++98
-Wc++98-compat trailing return types are incompatible with C++98
-Wc++98-compat enumeration types with a fixed underlying type are incompatible with C++98
-Wc++98-compat alignof expressions are incompatible with C++98
-Wc++98-compat '%0' keyword is incompatible with C++98
-Wc++98-compat 'decltype' type specifier is incompatible with C++98
-Wc++98-compat deleted function definitions are incompatible with C++98
-Wc++98-compat consecutive right angle brackets are incompatible with C++98 (use '> >')
-Wc++98-compat static_assert declarations are incompatible with C++98
-Wc++98-compat scoped enumerations are incompatible with C++98
-Wc++98-compat lambda expressions are incompatible with C++98
-Wc++98-compat attributes are incompatible with C++98
-Wc++98-compat 'alignas' is incompatible with C++98
-Wc++98-compat noexcept specifications are incompatible with C++98
-Wc++98-compat literal operators are incompatible with C++98
-Wc++98-compat noexcept expressions are incompatible with C++98
-Wc++98-compat 'nullptr' is incompatible with C++98
-Wc++98-compat-pedantic extra '' outside of a function is incompatible with C++98
-Wc++98-compat-pedantic extern templates are incompatible with C++98
-Wc++98-compat-pedantic commas at the end of enumerator lists are incompatible with C++98
-Wdangling-else add explicit braces to avoid dangling else
-Wdeprecated Use of 'long' with '__vector' is deprecated
-Wdeprecated-declarations use of C-style parameters in Objective-C method declarations is deprecated
-Wdeprecated-register 'register' storage class specifier is deprecated
-Wduplicate-decl-specifier duplicate '%0' declaration specifier
-Wextra-semi extra ';' after member function definition
-Wextra-tokens "extra tokens at the end of '#pragma omp %0' are ignored
-Wgcc-compat GCC does not allow %0 attribute in this position on a function definition
-Wignored-attributes attribute %0 ignored, because it is not attached to a declaration
-Wmicrosoft-exists dependent %select{__if_not_exists|__if_exists}0 declarations are ignored
-Wmissing-selector-name %0 used as the name of the previous parameter rather than as part of the selector
-Wsemicolon-before-method-body semicolon before method body is ignored
-Wsource-uses-openmp "unexpected '#pragma omp ...' in program
-Wstatic-inline-explicit-instantiation ignoring '%select{static|inline}0' keyword on explicit template instantiation
原博主：http://www.jianshu.com/p/eb03e20f7b1c
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