[PATCH 1/9] Add a target to check example programs

[Stephen Kitt <steve@sk2.org>]

This is a first step to automating example program checks. It extracts
source snippets introduced by "Program source", assuming it's C, and
attempts to compile it.

For now, only man pages with a single "Program source" entry are
processed. The compiled code isn't linked to avoid having to handle
library requirements (e.g. -ldl).

Signed-off-by: Stephen Kitt <steve@sk2.org>
---
 Makefile | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/Makefile b/Makefile
index 0da0328d8..3f597d7c3 100644
--- a/Makefile
+++ b/Makefile
@@ -266,6 +266,23 @@ check-groff-warnings:
 	done; \
 	rm -f "$$GROFF_LOG"
 
+# Check that man pages' examples programs (for now, only pages with a
+# single program) actually compile
+.PHONY: check-example-programs
+check-example-programs:
+	GCC_LOG="$$(mktemp --tmpdir manpages-checksXXXX)" || exit $$?; \
+	for manpage in $$(grep -rc 'Program source' man?/* | grep ':1$$' | cut -d: -f1); \
+	do \
+		(man -Tutf8 $$manpage | \
+			col -bx | \
+			sed -n '/Program source/,/^[[:space:]]\{0,3\}[^[:space:]]/p' | \
+			tail -n+2 | \
+			head -n-1 | \
+			gcc -xc -c -o/dev/null -) 2>| "$$GCC_LOG"; \
+		[ -s "$$GCC_LOG" ] && { echo "$$manpage: "; cat "$$GCC_LOG"; echo; }; \
+	done; \
+	rm -f "$$GCC_LOG"
+
 # someone might also want to look at /var/catman/cat2 or so ...
 # a problem is that the location of cat pages varies a lot
 
-- 
2.30.2