The following attributes are supported in part or in whole. For more information, see the GCC documentation.

• alias

• aligned

  This attribute is supported on:

  • typedef declarations

  • enum types

  • struct and union types and members

  • variables, except register variables.

  In contrast to the GCC implementation, the attribute is neither supported on functions nor on (pointer) function parameters. Additional limitations might also apply, such as auto variables not being allowed to have a stricter alignment than the stack.

• always_inline

  In contrast to the GCC implementation, the attribute implies inline on the function, and no diagnostic message will be produced when always_inline is used on a non-inline function.

• cmse_nonsecure_call

  See also __cmse_nonsecure_call.

• cmse_nonsecure_entry

  See also __cmse_nonsecure_entry.

• cold

  This attribute sets the optimization goal for the function to optimizing for Size. If the optimization goal has also been set using #pragma optimize, the GCC-style attribute overrides it. If there is a conflict, a warning will be issued.

  In contrast to the GCC implementation, the attribute can only be used as a function attribute, not in a label.

• const

• constructor

  Functions with the attribute constructor will be called at the end of dynamic initialization—after static initialization, and before main is called. If the attribute is used on multiple functions, they will be called in the order of definition.

  The attribute is recognized, but has no effect, when used on objects compiled with the option ‑‑shared.

• deprecated

• format

• hot

  This attribute sets the optimization goal for the function to optimizing for Speed. If the optimization goal has also been set using #pragma optimize, the GCC-style attribute overrides it. If there is a conflict, a warning will be issued.

  In contrast to the GCC implementation, the attribute can only be used as a function attribute, not in a label.

• naked

• noinit

  In contrast to the GCC implementation, the attribute only applies to variables, and any such variable is treated as if it were declared with the IAR __no_init keyword.

• noinline

• nonnull

  The attribute is recognized but has no effect.

• noreturn

• packed

  When used on an enum definition, the packed attribute has an effect only if the option ‑‑enum_is_int has been specified. In that case the smallest possible underlying type is selected for the enum. (This is otherwise the default behavior for the compiler).

  Note that when using the GCC-style attribute packed, no diagnostics messages are produced for potential unaligned struct member accesses. To be informed of such accesses, use the IAR type attribute __packed.

• pcs (for IAR type attributes used on functions)

• pure

• section

• target (for IAR object attributes used on functions)

• unused

• used

• visibility

  For reference information, see visibility.

• volatile

• warn_unused_result

• weak

  Note that when the IAR attribute __weak is used on a declaration or on a tentative definition with a subsequent definition, the object is not made weak. Using the GCC-style attribute weak, the object will be made weak.