Makefile

#
# Makefile used for compiling C++ programs and caching both their executables and compilation outputs.
#
# For each program, its compilation output is written to a file and kept together with the executable.
# Naming format:
#	Pragram:             my_program.cpp
#	Executable:          my_program.exe
#	Compilation output:  ._my_program.cpp.compile.out 
# The compilation output is kept so that it can be read later, e.g. to find if there were compilation warnings.
# The Makefile output itself is not dependable in such scenarios since the compilation is not run again if the source is not modified.
# 
# Used Makefile features/concepts are commented through the code.
#

# Defining some recursively expanded variables

CXXFLAGS=-std=gnu++1y -Wall -Wextra -O2 -static

CPP_EXT=cpp
HEADER_EXT=h
EXE_EXT=exe
COMPILE_OUT_PREFIX=._
CPP_COMPILE_OUT_SUFFIX=.$(CPP_EXT).compile.out
CPP_COMPILE_TMP_OUT_SUFFIX=.$(CPP_EXT).compile.tmp.out

# Forcing 'make' to use 'bash' instead of 'sh'.
# Otherwise, "set -o pipefail" will not work.
SHELL=/bin/bash

# Defining some simply expanded variables
# Using 'wildcard' function to find all C++ sources and headers
CPP_HEADERS := $(wildcard *.$(HEADER_EXT))
CPP_SOURCES := $(wildcard *.$(CPP_EXT))
# Defining variables through substitution references
EXECUTABLES := $(CPP_SOURCES:%.$(CPP_EXT)=%.$(EXE_EXT))
COMPILE_OUTPUTS := $(CPP_SOURCES:%.$(CPP_EXT)=$(COMPILE_OUT_PREFIX)%$(CPP_COMPILE_OUT_SUFFIX))

# Defining .PHONY targets
.PHONY: all clean compile_outputs_list

all: $(EXECUTABLES) $(COMPILE_OUTPUTS)

clean:
	rm -f *.$(EXE_EXT) $(COMPILE_OUT_PREFIX)*$(CPP_COMPILE_TMP_OUT_SUFFIX) $(COMPILE_OUT_PREFIX)*$(CPP_COMPILE_OUT_SUFFIX)

# Suppressing recipe echoing with @
compile_outputs_list:
	@echo $(COMPILE_OUTPUTS)

# Using 'shell' function
coloring_enabled := $(shell if [ -t 2 ] ; then echo true ; else echo false ; fi)
# Using Makefile conditionals
ifeq ($(coloring_enabled),true)
  cpp_coloring_flag=-fdiagnostics-color=always
else
  cpp_coloring_flag=-fdiagnostics-color=never
endif

# Defining pattern rules with more than one target
# Defining pattern-specific variable values
CPP_TARGET_PATTERNS=%.$(EXE_EXT) $(COMPILE_OUT_PREFIX)%$(CPP_COMPILE_OUT_SUFFIX)
$(CPP_TARGET_PATTERNS): COMPILE_TMP_OUTPUT=$(COMPILE_OUT_PREFIX)$*$(CPP_COMPILE_TMP_OUT_SUFFIX)
$(CPP_TARGET_PATTERNS): COMPILE_OUTPUT=$(COMPILE_OUT_PREFIX)$*$(CPP_COMPILE_OUT_SUFFIX)
$(CPP_TARGET_PATTERNS): COMPILE_COMMAND=g++ $(CXXFLAGS) $< -o $*.$(EXE_EXT) $(cpp_coloring_flag)
$(CPP_TARGET_PATTERNS): %.$(CPP_EXT) $(CPP_HEADERS) 
	@echo $(COMPILE_COMMAND)
	@set -o pipefail  &&  $(COMPILE_COMMAND) 2>&1  |  tee -i $(COMPILE_TMP_OUTPUT) 1>&2
	@mv $(COMPILE_TMP_OUTPUT) $(COMPILE_OUTPUT)