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From: bill@valiant (R.A.L Williams)
Newsgroups: comp.lang.ada
Subject: "Subtract C, add Ada"
Date: 23 Jan 1995 08:49:41 GMT
Organization: GEC-Marconi Research Centre
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Date: 1995-01-23T08:49:41+00:00
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In article <3feevh$615@gnat.cs.nyu.edu> Robert Dewar wrote:
: "Dennis Ritchie once said in an interview that there is *nothing* in the
:  C language that keeps compiler writers from issuing stringent warnings
:  about stuff that most Ada people take for granted."

: Dennis may have said this, but it is misleading. Yes, there is stuff that
: Ada people take for granted that C compilers could (and in some compilers
: *do*) check for.

: But there are lots of things that Ada people take for granted that cannot
: be checked in C, there just isn't enough information. C has no separation
: of scalar types, no ranges on scalar types, and the ubquitous use of
: pointers, and their similarity to arrays means that sophisticated aliasing
: analysis is required to even approximate the type checking that occurs
: in the context of access types in Ada. There are many other examples.

Ranges - no, but my Microsoft C compiler certainly *does* warn me when I
 - mix signed and unsigned integers (of course, Ada83 doesn't have unsigned)
 - assign the result of 'long' expressions to shorts or chars etc.
 - perform 'unchecked conversion' between integers and pointers

There are probably other things as well, but these are certainly some of the
gripes it comes up with when I try to port typical UNIX C code to WIN32.

I agree with Dennis Ritchie, If I go to the trouble of typedef'ing a new
type, there is nothing to stop the compiler from griping at me if I
do something inappropriate with it. This is mainly a compiler issue, not
a language issue.

Bill Williams