Ensure 'doc' Make Target Is Supported; Add Diagnostic Information If …

…Documentation Is Disabled (#1503)

* Ensure the 'doc' target is supported per 'make help'. Also, provide useful diagnostic infomration if Doxygen is not available or if documentation support has been explicitly disabled.

* Qualify the negated CHIP_BUILD_DOCS case with the 'doc' and 'docdist' targets.

Makefile.am

@@ -207,6 +207,14 @@ dist-hook: $(distdir)/.dist-version
 distclean-local:
 	$(MAKE) -C $(srcdir) -f Makefile-bootstrap clean-repos
 
+#
+# Top-level convenience target for making documentation.
+#
+
+.PHONY: doc
+doc: $(BUILT_SOURCES)
+	$(MAKE) -C docs $(@)
+
 #
 # Top-level convenience target for making a documentation-only
 # distribution whose results appear at the top level of the build tree

docs/Makefile.am

@@ -60,9 +60,11 @@ CLEANFILES                                      = \
     $(chip_docdist_archive)                      \
     $(NULL)
 
+.PHONY: doc docdist
+
 if CHIP_BUILD_DOCS
 
-all-local: html/index.html
+all-local doc: html/index.html
 
 #
 # We choose to manually transform Doxyfile.in into Doxyfile here in
@@ -106,6 +108,11 @@ docdist $(chip_docdist_alias): $(chip_docdist_archive)
 clean-local:
 	$(AM_V_at)rm -f -r html
 
+else
+
+doc docdist:
+	$(error "Documentation support is disabled. Please explicitly enable documentation with `--enable-docs` via `configure` and/or ensure that Doxygen is installed")
+
 endif # CHIP_BUILD_DOCS
 
 include $(abs_top_nlbuild_autotools_dir)/automake/post.am