Makefile for compiling Markdown files to a single PDF - makefile

Question

I am trying to use a Makefile for compiling a PDF when any of a number of Markdown files change:
# Compile report
source := draft
output := dist
sources := $(wildcard $(source)/*.md)
objects := $(patsubst %.md,%.pdf,$(subst$(source),$(output),$(sources)))
all: $(objects)
report-print.md: $(source)/%.md
cat draft/*.md | pandoc \
--variable geometry:a4paper \
--number-sections \
--toc \
--f markdown \
-s \
-o dist/report-print.pdf \
.PHONY : clean
clean:
rm -f $(output)/*.pdf
I get an error:
make: *** No rule to make target `dist/01-title.pdf', needed by `all'. Stop.
The file draft/01-title.md is one of of the source files.

Answer 1

You don't have a rule for creating one .pdf file from one .md file. Which is fine, because that's not what you want to do. You want to create a single pdf file from all the .md files (as I understand it). So, ditch all the objects stuff; you don't need to create all those individual pdf files.
There are a number of other minor problems: you aren't creating the same filename as your target (report-print.md vs. $(output)/report-print.pdf), you should use automatic variables, etc.)
Your makefile will simply be:
source := draft
output := dist
sources := $(wildcard $(source)/*.md)
all: $(output)/report-print.pdf
$(output)/report-print.pdf: $(sources)
cat $^ | pandoc \
--variable geometry:a4paper \
--number-sections \
--toc \
--f markdown \
-s \
-o $#
.PHONY : clean
clean:
rm -f $(output)/*.pdf