Annex B (informative) Implementation quantities [implimits]

Implementations can exhibit limitations for various quantities; some possibilities are presented in the following list.

The bracketed number following each quantity is a potential minimum value for that quantity.

(1.1)
Nesting levels of compound statements ([stmt.block]), iteration control structures ([stmt.iter]), and selection control structures ([stmt.select]) [256].
(1.2)
Nesting levels of conditional inclusion ([cpp.cond]) [256].
(1.3)
Pointer ([dcl.ptr]), pointer-to-member ([dcl.mptr]), array ([dcl.array]), and function ([dcl.fct]) declarators (in any combination) modifying a type in a declaration [256].
(1.4)
Nesting levels of parenthesized expressions ([expr.prim.paren]) within a full-expression [256].
(1.5)
Number of characters in an internal identifier ([lex.name]) or macro name ([cpp.replace]) [1 024].
(1.6)
Number of characters in an external identifier ([lex.name], [basic.link]) [1 024].
(1.7)
External identifiers ([basic.link]) in one translation unit [65 536].
(1.8)
Identifiers with block scope declared in one block ([basic.scope.block]) [1 024].
(1.9)
Structured bindings ([dcl.struct.bind]) introduced in one declaration [256].
(1.10)
Macro identifiers ([cpp.replace]) simultaneously defined in one translation unit [65 536].
(1.11)
Parameters in one function definition ([dcl.fct.def.general]) [256].
(1.12)
Arguments in one function call ([expr.call]) [256].
(1.13)
Parameters in one macro definition ([cpp.replace]) [256].
(1.14)
Arguments in one macro invocation ([cpp.replace]) [256].
(1.15)
Characters in one logical source line ([lex.phases]) [65 536].
(1.16)
Characters in a string-literal ([lex.string]) (after concatenation ([lex.phases])) [65 536].
(1.17)
Size of an object ([intro.object]) [262 144].
(1.18)
Nesting levels for #include files ([cpp.include]) [256].
(1.19)
Case labels for a switch statement ([stmt.switch]) (excluding those for any nested switch statements) [16 384].
(1.20)
Non-static data members (including inherited ones) in a single class ([class.mem]) [16 384].
(1.21)
Lambda-captures in one lambda-expression ([expr.prim.lambda.capture]) [256].
(1.22)
Enumeration constants in a single enumeration ([dcl.enum]) [4 096].
(1.23)
Levels of nested class definitions ([class.nest]) in a single member-specification [256].
(1.24)
Functions registered by atexit() ([support.start.term]) [32].
(1.25)
Functions registered by at_quick_exit() ([support.start.term]) [32].
(1.26)
Direct and indirect base classes ([class.derived]) [16 384].
(1.27)
Direct base classes for a single class ([class.derived]) [1 024].
(1.28)
Class members declared in a single member-specification (including member functions) ([class.mem]) [4 096].
(1.29)
Final overriding virtual functions in a class, accessible or not ([class.virtual]) [16 384].
(1.30)
Direct and indirect virtual bases of a class ([class.mi]) [1 024].
(1.31)
Static data members of a class ([class.static.data]) [1 024].
(1.32)
Friend declarations in a class ([class.friend]) [4 096].
(1.33)
Access control declarations in a class ([class.access.spec]) [4 096].
(1.34)
Member initializers in a constructor definition ([class.base.init]) [6 144].
(1.35)
initializer-clauses in one braced-init-list ([dcl.init]) [16 384].
(1.36)
Scope qualifications of one identifier ([expr.prim.id.qual]) [256].
(1.37)
Nested linkage-specifications ([dcl.link]) [1 024].
(1.38)
Recursive constexpr function invocations ([dcl.constexpr]) [512].
(1.39)
Full-expressions evaluated within a core constant expression ([expr.const]) [1 048 576].
(1.40)
Template parameters in a template declaration ([temp.param]) [1 024].
(1.41)
Recursively nested template instantiations ([temp.inst]), including substitution during template argument deduction ([temp.deduct]) [1 024].
(1.42)
Handlers per try block ([except.handle]) [256].
(1.43)
Number of placeholders [10].
(1.44)
Number of hazard-protectable possibly-reclaimable objects ([saferecl.hp.general]) [256].