Re: GNU make troubleshooting

[Jeffrey Walton]

On Tue, Jul 11, 2023 at 9:44 AM Paul Smith <psmith@gnu.org> wrote:
>
> On Mon, 2023-07-10 at 17:17 -0400, Jeffrey Walton wrote:
> > Yes, lots of conditionals and lots of shell'ing, like:
> >
> > GREP ?= grep
> > SED ?= sed
> >
> > ifneq ($(wildcard /usr/xpg4/bin/grep),)
> >   GREP := /usr/xpg4/bin/grep
> > endif
> > ifneq ($(wildcard /usr/xpg4/bin/sed),)
> >   SED := /usr/xpg4/bin/sed
> > endif
> >
> > SUN_COMPILER := $(shell $(CXX) -V 2>&1 | $(GREP) -i -c -E 'CC:
> > (Sun|Studio)')
> > GCC_COMPILER := $(shell $(CXX) --version 2>/dev/null | $(GREP) -v -E
> > '(llvm|clang)' | $(GREP) -i -c -E '(gcc|g\+\+)')
> > XLC_COMPILER := $(shell $(CXX) -qversion 2>/dev/null |$(GREP) -i -c
> > "IBM XL")
> > CLANG_COMPILER := $(shell $(CXX) --version 2>/dev/null | $(GREP) -i -
> > c
> > -E '(llvm|clang)')
> > INTEL_COMPILER := $(shell $(CXX) --version 2>/dev/null | $(GREP) -i -
> > c
> > '\(icc\)')
> > ...
>
> But, what about this do you want to know?

I want to see an output for the evaluation of each statement, like
what I would see with 'set -x'. I need to know where something goes
sideways when shell'ing out in a pipe.

> If what you want to know is "what was the result of all this", the
> database print (-p) option will show you what make computed as the
> final value for each of these variables, and also what linenumber of
> the makefile was used to set the final version:
>
>   # makefile (from 'Makefile', line 12)
>   GCC_COMPILER := 0
>    ...
>   # makefile (from 'Makefile', line 1)
>   GREP = grep
>    ...
>
> I don't want to suggest that everything is just peachy.  There are lots
> of rough edges for working with GNU Make and Makefiles, there is no
> question about that.  I'm just trying to understand clearly what things
> will actually be useful, rather than simply spewing out more output
> similar to what -d does.

Here's 'make -d' for a project I help maintain. No info on the
evaluations shown above, which would be useful to me. There is lots of
information that looks like it would be useful to a GNU Make
maintainer.

$ make -d
GNU Make 4.3
Built for x86_64-pc-linux-gnu
Copyright (C) 1988-2020 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Reading makefiles...
Reading makefile 'GNUmakefile'...
Updating makefiles....
 Considering target file 'GNUmakefile'.
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Updating goal targets....
Considering target file 'default'.
 File 'default' does not exist.
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   File 'cryptest.exe' does not exist.
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g++ -DNDEBUG -g2 -O3 -fPIC -pthread -pipe -c cryptlib.cpp

> I do agree with Bruno that there is a lot of implicit knowledge for
> working with Makefiles that is not well described, or in some cases
> even hinted at, in the manual.  Maybe I'll try to add a new chapter
> this weekend... writing will be a nice change from hacking.  I've spent
> enough time on StackOverflow that I have a good idea of the places
> people have troubles.

I'm not sure what folks are doing on Stack Overflow.

We use GNU Make for its power. If we did not want/need the power, then
we would use an anemic make, like Posix make.

Jeff