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| -rw-r--r-- | doc/extensions.md | 43 |
1 files changed, 0 insertions, 43 deletions
diff --git a/doc/extensions.md b/doc/extensions.md index 9d07972..b3417a9 100644 --- a/doc/extensions.md +++ b/doc/extensions.md @@ -5,12 +5,6 @@ may be implemented in the future. ## Implemented -### `__typeof__` - -`__typeof__(E)` is a type specifier for the type of expression `E`. Arrays -and function designator expressions do not decay into pointers, just -like when used with `sizeof`. - ### `__asm__` labels A declarator can be followed by `__asm__("somelabel")` to specify the @@ -32,30 +26,6 @@ rules. The name may contain characters not allowed in regular identifiers. - **`__builtin_va_list`**: Built-in suitable for implementing the `va_list` type. - **`__builtin_va_start`**: Built-in suitable for implementing the `va_start` macro. -### Enumerator values outside the range of `int` - -ISO C requires that enumerator values be in the range of `int`. GNU C -allows any integer value, at the cost of enumerator constants possibly -having different types inside and outside the `enum` specifier. - -In the following example, `A` has type `unsigned` inside the `enum` -specifier, and `long` outside, so both of the assertions fail. - -```c -enum E { - A = 0x80000000, - B = sizeof(A), - C = A < -1, - D = -1, -}; -_Static_assert(B == sizeof(A), "sizeof(A) changed"); -_Static_assert(C == A < -1, "signedness of typeof(A) changed"); -``` - -As a compromise, we allow enumerator values larger than `INT_MAX` and -less than or equal to `UINT_MAX`, but only if no other enumerators have -a negative value. This way, enumerator constants have a fixed type. - ## Missing ### Statement expressions @@ -69,19 +39,6 @@ the statement expression. GNU C allows empty top-level declarations (i.e. `;`). -### Empty initializer list - -GNU C allows empty initializer lists when initializing an object, -for example - -```c -struct { - int a, b; -} s = {}; -``` - -This behaves exactly the same as `{0}`. - ### Missing operand in conditional expression GNU C allows you to omit the second operand in conditional expressions, |