Running make from Outside the Tree

Let's say I have a makefile like the following:

CXXFLAGS := -I./Include

Foo:
    $(CXX) $(CXXFLAGS) -o Foo

If the user cds into the source tree and runs make, everything is fine and dandy. However, if make is invoked from somewhere outside the source tree, the include directory will be incorrect.

Using full paths instead of relative paths works, but that de开发者_运维知识库stroys the portability of the makefile.

Should I just rely on users invoking make "properly?" Or is there an easy way to get around this?

If you want to have CXXFLAGS be -Isome_dir/Include when the make is invoked as
make -f some_dir/Makefile, MAKEFILE_LIST might meet the purpose.
For example:

MAKEFILE_DIR := $(dir $(lastword $(MAKEFILE_LIST)))
CXXFLAGS := -I$(MAKEFILE_DIR)Include

If your make's version is 3.80 or lower, lastword might not work.
In that case, $(word $(words $(MAKEFILE_LIST)),$(MAKEFILE_LIST)) will work instead.

EDIT: This answer is for GNU-make.

Use the -C flag.

make -C my_dir

You could present your users a compile command that looks like (cd /to/proper/directory && make -k)