Re: What is the meaning of an expression?

On 1/19/22 12:18 AM, gah4 wrote:


> So, back to anthropomorphic computers and logical
> inconsistencies. How good are compilers, especially ones
> that evaluate constant expressions at compile time, at
> dealing with logic failure?


Optimization is a special science. A compiler might evaluate a constant
expression properly, in the sense that evaluation at runtime might fail
due to overflows of too narrow types in compiled code.


> And especially, as the question
> needs, expressions that don't have a value?


Aren't these called *statements*?
Syntax does not normally allow for expressions without values,
semantics disallow the use of subroutines without a return type as part
of an expression.


Expressions always have a value, but if that value is not used further
then the compiler can ignore that part of the source code. Problems can
arise from unrecognized side effects or exceptions eliminated by dead
code elimination.


DoDi

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