URL:
<https://savannah.gnu.org/bugs/?59243>
Summary: Overcomplicated example of automatic dependency
configuration
Project: make
Submitted by: None
Submitted on: Fri 09 Oct 2020 03:49:50 PM UTC
Severity: 3 - Normal
Item Group: Documentation
Status: None
Privacy: Public
Assigned to: None
Open/Closed: Open
Discussion Lock: Any
Component Version: None
Operating System: None
Fixed Release: None
Triage Status: None
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Details:
In section 4.14, the example of the pattern rule is unnecessarily
complicated:
%.d: %.c
@set -e; rm -f $@; \
$(CC) -M $(CPPFLAGS) $< > $@.$$$$; \
sed 's,\($*\)\.o[ :]*,\1.o $@ : ,g' < $@.$$$$ > $@; \
rm -f $@.$$$$
The first rm command is redundant as redirecting the output of the sed command
with ">" will replace it anyway. Instead of creating another temporary file
with "$@.$$$$", one can simply pipe the preprocessor output to sed input,
making the second rm unnecessary as well. If a file must be created for some
reason, why confuse beginners with "$@.$$$$" instead of just "$@.temp". The
sed is also overengineered as is.
This example provides the same functionality:
%.d: %.c
@printf "$@ " > $@
@$(CC) $(CPPFLAGS) -MM $< >> $@
However, instead of spending 30 minutes to understand it, the developer only
needs 5, as this example would be much clearer.
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