'Tab's in Makefile

I have Makefile that contains tabified line echo $(foo) and untabified line ifneq (,$(findstring i, $(MAKEFLAGS))):

bar =
foo = $(bar)

all:
    echo $(foo)
ifneq (,$(findstring i, $(MAKEFLAGS)))
    echo "i was passed to MAKEFLAGS"
endif

If I untabify echo $(foo) I got error:

Makefile:5: *** missing separator.  Stop.

Why some lines should be tabified while other ones - not?

makefile


Solution 1:[1]

Why some lines should be tabified while other ones - not?

Every line of each recipe must begin with a tab. Every line that is not part of a recipe should not begin with a tab. The crux of the issue is that in the example makefile, your ifneq and endif directives are not part of a recipe. They are processed by make, during makefile parsing, not passed to a shell when the recipe is run. In some ways, this is the same kind of distinction as between C preprocessing directives and the surrounding source code.

Sources

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Source: Stack Overflow

Solution Source
Solution 1 John Bollinger

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