Re: as/ld silently creates programs with undefined references/symbols

[Nick Clifton]

Hi Russell,

> However, I'm still concerned that ld was able to successfully link to a
> binary with --no-undefined, and the resulting binary still had undefined
> symbols.
>
> Could someone explain why --no-undefined didn't catch the problem?

Because "--no-undefined" actually means "do not allow any references to 
undefined symbols" rather than "do not allow any undefined symbols".

What was happening was that the code in GAS was silently converting the 
reference to the undefined symbol into the value 0.  ie it was not 
generating a reloc against the undefined symbol, it was just ignoring 
it.  Thus the object file did not contain any relocations and so the 
linker did not encounter any references to undefined symbols, and so no 
warnings or errors were produced.

> Nick, thanks - this patch solves the assembler problem.  It correctly
> issues an error thusly:
>
> t.s: Assembler messages:
> t.s:3: Error: undefined symbol UNDEFINED_SYMBOL used as an immediate value

Great - I will check the patch into the mainline sources.

Cheers
  Nick