build_html: add some hints about build deps

1 files changed, 12 insertions, 0 deletions

diff --git a/bin/build_html b/bin/build_html
index 0a3d7f6..67fc067 100755
--- a/bin/build_html
+++ b/bin/build_html
@@ -32,6 +32,7 @@ if test -n "${MMDC:-}" || command -v "mmdc" >&/dev/null; then
     # (The conversion involves npm and a headless chrome browser,
     # to it is understandable that not everybody would want to do it
     # this way.)
+    echo "Using mermaid-cli to pre-render mermaid diagrams"
 
     TMPDIR=$(mktemp -d "${TOPLEVEL}/tmp_mmdc.XXXXXXXX")
     trap 'rm -rf "$TMPDIR"' 0
@@ -47,6 +48,8 @@ elif test -n "${MDBOOK_MERMAID:-}" || command -v "mdbook-mermaid" >&/dev/null; t
     # This is much easier to run locally, but it requires that your
     # browser has enough client-side javascript in order to run
     # mermaid.  It doesn't touch npm.
+    echo "Using mdbook-mermaid to set up dynamic rendering of mermaid diagrams"
+
     MDBOOK_MERMAID=${MDBOOK_MERMAID:=mdbook-mermaid}
     TMPDIR=$(mktemp -d "${TOPLEVEL}/tmp_mdbook_mermaid.XXXXXXXX")
     trap 'rm -rf "$TMPDIR"' 0
@@ -60,10 +63,19 @@ else
     #
     # In this case we run mdbook on our inputs unchanged.
     # The mermaid blocks will render as code.
+    echo "No mermaid support found; mermaid diagrams will be unrendered"
+
     MDBOOK_OUTPUT_DIR=""
     MDBOOK_DIR="$TOPLEVEL/mdbook"
 fi
 
+# mdbook-linkcheck is a non-obvious dependency, and the mdbook output when it's
+# not found doesn't spell out how to install it.
+if ! command -v mdbook-linkcheck; then
+    echo 'ERROR: mdbook-linkcheck not found. You should probably install it with `cargo install mdbook-linkcheck`'
+    exit 1
+fi
+
 $MDBOOK build "${MDBOOK_DIR}/spec"
 $MDBOOK build "${MDBOOK_DIR}/proposals"