From 65874bd5808285c84149f80a6eece77e834e3538 Mon Sep 17 00:00:00 2001
From: Pierre Villemot <pierre.villemot@ocamlpro.com>
Date: Tue, 30 Jul 2024 14:14:20 +0200
Subject: [PATCH] Rewrite the gen_link_flags script in OCaml

---
 src/bin/text/dune              | 13 ++++-
 src/bin/text/gen-link-flags.sh | 56 --------------------
 src/bin/text/gen_link_flags.ml | 97 ++++++++++++++++++++++++++++++++++
 3 files changed, 108 insertions(+), 58 deletions(-)
 delete mode 100755 src/bin/text/gen-link-flags.sh
 create mode 100644 src/bin/text/gen_link_flags.ml

diff --git a/src/bin/text/dune b/src/bin/text/dune
index 793e68dc2..c1c868de4 100644
--- a/src/bin/text/dune
+++ b/src/bin/text/dune
@@ -1,9 +1,18 @@
 (documentation
   (package alt-ergo))
 
+(executable
+  (name gen_link_flags)
+  (libraries unix fmt stdcompat cmdliner)
+  (modules gen_link_flags)
+  (promote (until-clean)))
+
 (rule
- (with-stdout-to link_flags.dune
-  (run ./gen-link-flags.sh %{env:LINK_MODE=dynamic} %{ocaml-config:system})))
+ (target link_flags.dune)
+ (deps (:gen gen_link_flags.exe))
+ (action
+   (with-stdout-to link_flags.dune
+    (run %{gen} --link-mode %{env:LINK_MODE=dynamic} --os %{ocaml-config:system}))))
 
 (executable
   (name Main_text)
diff --git a/src/bin/text/gen-link-flags.sh b/src/bin/text/gen-link-flags.sh
deleted file mode 100755
index 5baf95db4..000000000
--- a/src/bin/text/gen-link-flags.sh
+++ /dev/null
@@ -1,56 +0,0 @@
-#!/bin/sh
-
-set -ue
-
-LINK_MODE="$1"
-OS="$2"
-FLAGS=
-CCLIB=
-
-case "$LINK_MODE" in
-  dynamic)
-    ;; # No extra flags needed
-  static)
-    case "$OS" in
-      linux)
-        CCLIB="-static -no-pie";;
-      *)
-        echo "No known static compilation flags for '$OS'" >&2
-        exit 1
-    esac;;
-  mixed)
-    FLAGS="-noautolink"
-    # Note: for OCaml 5, use -lcamlstrnat and -lunixnat and mind zlib
-    # https://github.com/ocaml/ocaml/issues/12562
-    CCLIB="-lcamlzip -lnums -lzarith -lcamlstr -lunix -lz"
-    LIBS="gmp"
-    case "$OS" in
-      linux)
-        for lib in $LIBS; do
-          CCLIB="$CCLIB -l$lib"
-        done
-	CCLIB="-Wl,-Bstatic $CCLIB -Wl,-Bdynamic";;
-      macosx)
-        for lib in $LIBS; do
-          if [[ $lib == lib* ]]; then
-            archive="$lib.a"
-          else
-            archive="lib$lib.a"
-          fi
-          CCLIB="$CCLIB $(pkg-config $lib --variable libdir)/$archive"
-        done;;
-      *)
-        echo "No known mixed compilation flags for '$OS'" >&2
-        exit 1
-    esac;;
-
-  *)
-    echo "Invalid link mode '$LINK_MODE'" >&2
-    exit 2
-esac
-
-echo '('
-echo ' -linkall'
-for f in $FLAGS; do echo " $f"; done
-for f in $CCLIB; do echo " -cclib $f"; done
-echo ')'
diff --git a/src/bin/text/gen_link_flags.ml b/src/bin/text/gen_link_flags.ml
new file mode 100644
index 000000000..949757936
--- /dev/null
+++ b/src/bin/text/gen_link_flags.ml
@@ -0,0 +1,97 @@
+type os = Linux | Macos
+type link_mode = Dynamic | Static | Mixed
+
+module Cmd = struct
+  open Cmdliner
+
+  let show l = List.map (fun (s, _) -> s) l
+
+  let os_term =
+    let all = [
+      ("linux", Linux);
+      ("macosx", Macos)
+    ]
+    in
+    let doc =
+      Fmt.str "Choose the operating system, $(docv) must be %s."
+        (Arg.doc_alts @@ show all)
+    in
+    Arg.(value & opt (enum all) Linux & info ["os"] ~docv:"OS" ~doc)
+
+  let link_mode_term =
+    let all = [
+      ("dynamic", Dynamic);
+      ("static", Static);
+      ("mixed", Mixed)
+    ]
+    in
+    let doc =
+      Fmt.str "Choose the operating system, $(docv) must be %s."
+        (Arg.doc_alts @@ show all)
+    in
+    Arg.(value & opt (enum all) Dynamic &
+         info ["link-mode"] ~docv:"MODE" ~doc)
+
+  let parse k =
+    let info = Cmd.info "rewrite-gen-link-flags" in
+    Cmd.v info Term.(ret (const k $ link_mode_term $ os_term))
+    |> Cmd.eval
+end
+
+let pkgconfig lib archive =
+  let cmd = Fmt.str "pkg-config %s --variable libdir" lib in
+  let output =
+    Unix.open_process_in cmd
+    |> In_channel.input_line
+    |> Option.get
+  in
+  Fmt.str "%s/%s" output archive
+
+let pp_lib ppf s = Fmt.pf ppf "-cclib %s" s
+
+
+let () =
+  let mixed_flags = ["-noautolink"] in
+  let mixed_cclib = [
+    "-lstdcompat_stubs";
+    "-lcamlzip";
+    "-lzarith";
+    "-lcamlstr";
+    "-lunix";
+    "-lnums";
+    "-lz"
+  ]
+  in
+  let libs = ["gmp"] in
+  let rc =
+    Cmd.parse @@ fun link_mode os ->
+    let flags, cclib =
+      match link_mode, os with
+      | Dynamic, _ -> [], []
+      | Static, Linux -> [], ["-static"; "-no-pie"]
+      | Mixed, Linux ->
+        let cclib = mixed_cclib @ List.map (fun s -> "-l" ^ s) libs in
+        mixed_flags, "-Wl,-Bdynamic" :: "-Wl,-Bstatic" :: cclib
+      | Mixed, Macos ->
+        let cclib = mixed_cclib @
+                    List.map
+                      (fun lib ->
+                         let archive =
+                           if Stdcompat.String.starts_with
+                               ~prefix:"lib" lib then
+                             Fmt.str "%s.a" lib
+                           else
+                             Fmt.str "lib%s.a" lib
+                         in
+                         pkgconfig lib archive
+                      ) libs
+        in
+        mixed_flags, cclib
+      | _ -> Fmt.invalid_arg "unsupported mode and OS"
+    in
+    Fmt.pr "@[(-linkall %a %a)@]"
+      Fmt.(list ~sep:sp string) flags
+      Fmt.(list ~sep:sp pp_lib) cclib;
+    `Ok ()
+  in
+  exit rc