CbC/CbC_gcc: gcc/ada/doc/gnat_rm/implementation_defined

comparison gcc/ada/doc/gnat_rm/implementation_defined_attributes.rst @ 131:84e7813d76e9

gcc-8.2

author	mir3636
date	Thu, 25 Oct 2018 07:37:49 +0900
parents	04ced10e8804
children	1830386684a0

comparison

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-:04ced10e8804
+:84e7813d76e9
 Attribute Valid_Scalars
 =======================
 .. index:: Valid_Scalars
-The ``'Valid_Scalars`` attribute is intended to make it easier to
+The ``'Valid_Scalars`` attribute is intended to make it easier to check the
-check the validity of scalar subcomponents of composite objects. It
+validity of scalar subcomponents of composite objects. The attribute is defined
-is defined for any prefix ``X`` that denotes an object.
+for any prefix ``P`` which denotes an object. Prefix ``P`` can be any type
-The value of this attribute is of the predefined type Boolean.
+except for tagged private or ``Unchecked_Union`` types. The value of the
-``X'Valid_Scalars`` yields True if and only if evaluation of
+attribute is of type ``Boolean``.
-``P'Valid`` yields True for every scalar part P of X or if X has
-no scalar parts. It is not specified in what order the scalar parts
+``P'Valid_Scalars`` yields ``True`` if and only if the evaluation of
-are checked, nor whether any more are checked after any one of them
+``C'Valid`` yields ``True`` for every scalar subcomponent ``C`` of ``P``, or if
-is determined to be invalid. If the prefix ``X`` is of a class-wide
+``P`` has no scalar subcomponents. Attribute ``'Valid_Scalars`` is equivalent
-type ``T'Class`` (where ``T`` is the associated specific type),
+to attribute ``'Valid`` for scalar types.
-or if the prefix ``X`` is of a specific tagged type ``T``, then
-only the scalar parts of components of ``T`` are traversed; in other
+It is not specified in what order the subcomponents are checked, nor whether
-words, components of extensions of ``T`` are not traversed even if
+any more are checked after any one of them is determined to be invalid. If the
-``T'Class (X)'Tag /= T'Tag`` . The compiler will issue a warning if it can
+prefix ``P`` is of a class-wide type ``T'Class`` (where ``T`` is the associated
-be determined at compile time that the prefix of the attribute has no
+specific type), or if the prefix ``P`` is of a specific tagged type ``T``, then
-scalar parts (e.g., if the prefix is of an access type, an interface type,
+only the subcomponents of ``T`` are checked; in other words, components of
-an undiscriminated task type, or an undiscriminated protected type).
+extensions of ``T`` are not checked even if ``T'Class (P)'Tag /= T'Tag``.
-For scalar types, ``Valid_Scalars`` is equivalent to ``Valid``. The use
+The compiler will issue a warning if it can be determined at compile time that
-of this attribute is not permitted for ``Unchecked_Union`` types for which
+the prefix of the attribute has no scalar subcomponents.
-in general it is not possible to determine the values of the discriminants.
+Note: ``Valid_Scalars`` can generate a lot of code, especially in the case of
-Note: ``Valid_Scalars`` can generate a lot of code, especially in the case
+a large variant record. If the attribute is called in many places in the same
-of a large variant record. If the attribute is called in many places in the
+program applied to objects of the same type, it can reduce program size to
-same program applied to objects of the same type, it can reduce program size
+write a function with a single use of the attribute, and then call that
-to write a function with a single use of the attribute, and then call that
 function from multiple places.
 Attribute VADS_Size
 ===================
 .. index:: Size, VADS compatibility

Mercurial > hg > CbC > CbC_gcc

comparison gcc/ada/doc/gnat_rm/implementation_defined_attributes.rst @ 131:84e7813d76e9