[Info-vax] VMS internals design, was: Re: BASIC and AST routines

[Chris Townley]

On 01/12/2021 21:23, hb wrote:
> On 12/1/21 8:50 PM, Stephen Hoffman wrote:
>> The Linker isn't particularly sensitive to API declarations, and will
>> probably not notice any API differences. API contract "enforcement" here
>> is usually by app failure.
>>
>> Otherwise—if BASIC won't play nice with a one-argument AST
>> declaration—specify the context pointer and whatever other four values
>> will be tolerated by BASIC and the Linker.
> 
> The linker matches symbols, which represent references and definitions.
> It complains if it can't find a matching definition for a reference. The
> symbol name and the symbol type must match. That is the linker knows
> about data and routines. It will not let you define an object for a
> routine reference. That's more or less all the linker does, here.
> 
> With C++ you get the API encoded in the symbol name, also known as
> "decorated" or "mangled" name. With matching such symbols the linker
> implicitly checks the API and does notice a difference, that is, it will
> print an unresolved reference warning. For example, if you call (or take
> the address of) "foo(int,int)" but only define a "foo(int)" you will see
> 
> %ILINK-I-UDFSYM,        CX3$_Z3FOOII2INROLH
> %ILINK-W-USEUNDEF, undefined symbol CX3$_Z3FOOII2INROLH referenced
>          source code name: "foo(int, int)"
> 

ADA picks that up at compile time

-- 
Chris