Type Attributes - Using the GNU Compiler Collection (GCC)
Description: Using the GNU Compiler Collection (GCC)

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### 6.33 Specifying Attributes of Types

The keyword `__attribute__` allows you to specify special attributes of types. Some type attributes apply only to `struct` and `union` types, while others can apply to any type defined via a `typedef` declaration. Other attributes are defined for functions (see Function Attributes), labels (see Label Attributes), enumerators (see Enumerator Attributes), and for variables (see Variable Attributes).

The `__attribute__` keyword is followed by an attribute specification inside double parentheses.

You may specify type attributes in an enum, struct or union type declaration or definition by placing them immediately after the `struct`, `union` or `enum` keyword. A less preferred syntax is to place them just past the closing curly brace of the definition.

You can also include type attributes in a `typedef` declaration. See Attribute Syntax, for details of the exact syntax for using attributes.