On Wed, 2023-06-07 at 12:23 +0200, Bartłomiej Wójcik wrote:
> The GNU make documentation states:
>
> *define myrule
> target:
> echo built
> endef
>
> $(myrule)
> *
To be clear, the documentation says that the above will NOT work (as
you intend).
> *The above makefile results in the definition of a target ‘target’
> with prerequisites ‘echo’ and ‘built’, as if the makefile contained
> target: echo built, rather than a rule with a recipe. Newlines still
> present in a line after expansion is complete are ignored as normal
> whitespace.*
>
> Why in that macro the whitespaces between *target:* and *echo built*
> are ignored?
They are not ignored in the macro. The macro contains the text:
target:
echo built
including the newlines and TAB etc.
They are ignored when the macro is expanded, then parsed as a rule.
That's because make's parser is fundamentally line-oriented, and
breaking up of lines happens BEFORE expansion. That means that AFTER
expansion, all whitespace including newlines is just treated like
normal whitespace: newlines no longer have their special significance
that they do during parsing and that entire output is considered just a
single logical line.
You can imagine it like make is adding backslashes to the end of every
line in the expanded output; that's not what actually happens but you
can think of it like that. So after expansion of the above, make sees:
target: \
echo built
> What is this property and what exactly does it refer to?
> Where is it stated in the documentation?
I mean, it's stated right there in the text you quoted so I'm not sure
what you mean.
