Defect Report #164

Submission Date: 16 Oct 95
Submittor: BSI
Source: Clive D.W. Feather
Question
Submitted to BSI by Clive D.W. Feather [email protected] .
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 012: Bad declarations
The C Standard contains no constraint to prevent declarations involving types not defined by subclause 6.1.2.5.
Subclause 6.5 states that:
A declaration shall declare at least a declarator, a tag, or the members of an enumeration. There seems to be no constraint that a declarator generate a well-formed type. Consider the following code:
{
int a [][5]; /* Line A */
int x, b [][5]; /* Line B */
}

Neither a nor b has a well formed type. Does line A nevertheless declare a declarator, or does it violate the quoted constraint? If it violates the constraint, does line B?
Is it the intent of the C Standard that an ill-formed (but syntactically correct) type generate a diagnostic? If so, then is there one, or does one need to be added?
Response
Line A declares a declarator. It violates the semantics described in subclause 6.5:
If an identifier for an object is declared with no linkage, the type for the object shall be complete by the end of its declarator, ...
But no diagnostic is required.
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