Defect Report #154
Submission Date: 16 Oct 95
Source: Clive D.W. Feather
Submitted to BSI by Clive D.W. Feather firstname.lastname@example.org.
In this Defect Report, identifiers lexically identical to those
declared in standard headers refer to the identifiers declared in those
standard headers, whether or not the header is explicitly mentioned.
This Defect Report has been prepared with considerable help from
Mark Brader, Jutta Degener, Ronald Guilmette, and a person whose
employment conditions require anonymity. However, except where stated,
opinions expressed or implied should not be assumed to be those of any
person other than myself.
Defect Report UK 002: Consistency of implementation-defined values
The restrictions that apply to "implementation-defined" entities
are not clear.
What restrictions apply to implementation-defined entities? If the
value of an expression is implementation-defined, need the
implementation always produce the same result?
For example, the value of the expressions 7/-3
and 8/-3 must each be either 3 or
2. Can an implementation make them different (that
is, use a different implementation-defined choice for each), or must it
make the same choice for all integral divisions involving a negative
As another example, can the number of significant characters and
the significance of case in an identifier with external linkage depend
on the identifier itself, or must it be the same for all possible
"Implementation defined" means just that: an implementation can
define any behavior even though it may not be constant.
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