Just always pip install ruff pyflakes3. (#788)

In the lint script, the logic for calling ruff and/or pyflakes or pyflakes3 got too tedious. Just pip install them every time and we know what to count on.

And since we'll then always have the virtualenv, this also installs clang-tidy in there, rather than looking for it installed with the OS.

tools/lint

@@ -14,6 +14,36 @@ PQXXVERSION="$(cd "$SRCDIR" && "$SRCDIR/tools/extract_version")"
 ARGS="${1:-}"
 
 
+set_up() {
+    MY_VENV="$(mktemp -d)"
+    if [ -z "$MY_VENV" ]
+    then
+        echo "Failed to set up virtualenv." >&2
+        exit 2
+    fi
+    virtualenv -q "$MY_VENV"
+    # shellcheck disable=SC1091
+    . "$MY_VENV/bin/activate"
+    pip install -q pyflakes ruff shellcheck-py
+}
+
+
+clean_up() {
+    if [ -n "${MY_VENV:-}" ] && [ "${VIRTUAL_ENV:-x}" = "${MY_VENV:-y}" ]
+    then
+        deactivate || true
+    fi
+    if [ -n "${MY_VENV:-}" ] && [ -d "${MY_VENV:-/nonexistent/dir}" ]
+    then
+        rm -r "$MY_VENV"
+    fi
+}
+
+
+trap clean_up EXIT
+set_up
+
+
 # Check that all source code is ASCII.
 #
 # I'd love to have rich Unicode, but I can live without it.  But we don't want
@@ -64,12 +94,8 @@ count_includes() {
 match_pre_post_headers() {
     local NAME TEMPDIR PRE POST
     NAME="$1"
-    TEMPDIR="$(mktemp -d)"
-    if test -z "$TEMPDIR"
-    then
-        echo >&2 "Could not create temporary directory."
-        exit 1
-    fi
+    TEMPDIR="$MY_VENV/tmp-lint"
+    mkdir -p  "$TEMPDIR"
     PRE="$TEMPDIR/pre"
     POST="$TEMPDIR/post"
     count_includes "$SRCDIR/$NAME-pre.hxx" >"$PRE"
@@ -97,38 +123,35 @@ check_compiler_internal_headers() {
 
 
 cpplint() {
-    local cxxflags dialect includes
+    local dialect includes
 
-    if which clang-tidy >/dev/null
+    pip install -q clang-tidy
+    if [ -e compile_flags ]
     then
-        if [ -e compile_flags ]
-        then
-            # Pick out relevant flags, but leave out the rest.
-            # If we're not compiling with clang, compile_flags may contain
-            # options that clang-tidy doesn't recognise.
-            dialect="$(grep -o -- '-std=[^[:space:]]*' compile_flags || true)"
-            includes="$(
-                grep -o -- '-I[[:space:]]*[^[:space:]]*' compile_flags ||
-                true)"
-        else
-            dialect=""
-            includes=""
-        fi
-
-        cxxflags="$dialect $includes"
+        # Pick out relevant flags, but leave out the rest.
+        # If we're not compiling with clang, compile_flags may contain
+        # options that clang-tidy doesn't recognise.
+        dialect="$(grep -o -- '-std=[^[:space:]]*' compile_flags || true)"
+        includes="$(
+            grep -o -- '-I[[:space:]]*[^[:space:]]*' compile_flags ||
+            true)"
+    else
+        dialect=""
+        includes=""
+    fi
 
 # TODO: Please, is there any way we can parallelise this?
 # TODO: I'd like cppcoreguidelines-*, but it's a tsunami of false positives.
 # TODO: Some useful checks in abseil-*, but it recommends "use our library."
 # TODO: Check test/, but tolerate some of the dubious stuff tests do.
-        clang-tidy \
-            "$(find "$SRCDIR"/src "$SRCDIR"/tools -name \*.cxx)" \
-            --checks=boost-*, \
-            -- \
-            -I"$SRCDIR/include" -Iinclude "$cxxflags"
-    fi
+    # shellcheck disable=SC2086,2046
+    clang-tidy "$SRCDIR"/src/*.cxx "$SRCDIR"/tools/*.cxx \
+        '--checks=boost-*', \
+        -- \
+        -I"$SRCDIR/include" -Iinclude $dialect $includes
 
     # Run Facebook's "infer" static analyser, if available.
+    # A "pip install" didn't work for me: No module named 'nltk'.
     # Instructions here: https://fbinfer.com/docs/getting-started/
     if which infer >/dev/null
     then
@@ -142,57 +165,22 @@ cpplint() {
 
 
 pylint() {
-    local venv
-
-    if ! which pyflakes -o ! which ruff >/dev/null
-    then
-        venv="$(mktemp -d)"
-        virtualenv "$venv"
-        # shellcheck disable=SC1091
-        . "$venv/bin/activate"
-    fi
-    if ! which pyflakes -a ! which pyflakes3 >/dev/null
-    then
-        pip install pyflakes
-    fi
-    if ! which ruff >/dev/null
-    then
-        pip install ruff
-    fi
-
-    if which pyflakes
-    then
-        pyflakes "$SRCDIR"/tools/*.py
-    else
-        pyflakes3 "$SRCDIR"/tools/*.py
-    fi
-
+    pyflakes "$SRCDIR"/tools/*.py
     ruff "$SRCDIR"/tools/*.py
-
-    if test -n "$venv"
-    then
-        deactivate
-        rm -r "$venv"
-    fi
 }
 
 
 shelllint() {
     local TLS="deprecations extract_version format lint todo update-copyright"
-    if which shellcheck >/dev/null
-    then
-        shellcheck "$SRCDIR/autogen.sh"
-        for s in $TLS
-        do
-            shellcheck "$SRCDIR/tools/$s"
-        done
-    else
-        echo "No shellcheck found.  Skipping."
-    fi
+    shellcheck "$SRCDIR/autogen.sh"
+    for s in $TLS
+    do
+        shellcheck "$SRCDIR/tools/$s"
+    done
 }
 
 
-markdownlint() {
+mdlint() {
     if which mdl >/dev/null
     then
         find . -name \*.md -exec mdl -c .markdownlint.yaml '{}' ';'
@@ -231,7 +219,7 @@ EOF
     shelllint
     check_news_version
     check_compiler_internal_headers
-    markdownlint
+    mdlint
     if [ $full == "yes" ]
     then
         cpplint