Improve support of clang

CHANGES

@@ -23,6 +23,10 @@ Next version
 - GPR#133, GPR#147: Allow default libraries to be marked as optional (David Allsopp, report by Romain Beauxis)
 - GPR#157: Improve flexlink support on Unix (for cross-compiling contexts).
   (Antonin Décimo, review by David Allsopp)
+- GPR#158: Reuse the compilers used during the build for later operations, such
+  as querying the compilers for their library search paths. Support parsing
+  clang output.
+  (Antonin Décimo, review by David Allsopp)
 
 Version 0.43
 - GPR#108: Add -lgcc_s to Cygwin's link libraries, upstreaming a patch from the

Makefile

@@ -38,9 +38,15 @@ CYGWIN64_PREFIX = x86_64-pc-cygwin-
 CYG64CC = $(CYGWIN64_PREFIX)gcc
 
 version.ml: Makefile flexdll.opam
-	echo "let version = \"$(VERSION)\"" > version.ml
-	echo "let mingw_prefix = \"$(MINGW_PREFIX)\"" >> version.ml
-	echo "let mingw64_prefix = \"$(MINGW64_PREFIX)\"" >> version.ml
+	echo 'let version = "$(VERSION)"' > $@
+	echo 'let mingw_prefix = "$(MINGW_PREFIX)"' >> $@
+	echo 'let mingw64_prefix = "$(MINGW64_PREFIX)"' >> $@
+	echo 'let msvc = "$(notdir $(MSVCC))"' >> $@
+	echo 'let msvc64 = "$(notdir $(MSVCC64))"' >> $@
+	echo 'let cygwin64 = "$(notdir $(CYG64CC))"' >> $@
+	echo 'let mingw = "$(notdir $(MINCC))"' >> $@
+	echo 'let mingw64 = "$(notdir $(MIN64CC))"' >> $@
+	echo 'let gnat = "gcc"' >> $@
 
 # Supported tool-chains
 

reloc.ml

@@ -24,7 +24,15 @@ let debug ?(dry_mode = {contents=false}) min_level fmt =
 let search_path = ref []
 let default_libs = ref []
 
-let gcc = ref "gcc"
+let cc = function
+  | `MSVC -> Version.msvc
+  | `MSVC64 -> Version.msvc64
+  | `CYGWIN64 -> Version.cygwin64
+  | `MINGW -> Version.mingw
+  | `MINGW64 -> Version.mingw64
+  | `GNAT | `GNAT64 -> Version.gnat
+  | `LIGHTLD -> failwith "No C compiler configured for this toolchain."
+
 let objdump = ref "objdump"
 
 let is_crt_lib = function
@@ -1173,7 +1181,7 @@ let build_dll link_exe output_file files exts extra_args =
         in
         Printf.sprintf
           "%s %s%s%s -L. %s %s -o %s %s %s %s %s"
-          !gcc
+          (cc !toolchain)
           (Option.fold ~none:"" ~some:(fun ld -> "-fuse-ld=" ^ ld ^ " ") !Cmdline.use_linker)
           (if link_exe = `EXE then "" else "-shared ")
           (if main_pgm then "" else if !noentry then "-Wl,-e0 " else if !machine = `x86 then "-Wl,-e_FlexDLLiniter@12 " else "-Wl,-eFlexDLLiniter ")
@@ -1195,7 +1203,7 @@ let build_dll link_exe output_file files exts extra_args =
         in
         Printf.sprintf
           "%s -m%s %s%s%s -L. %s %s -o %s %s %s %s %s %s"
-          !gcc
+          (cc !toolchain)
           !subsystem
           (Option.fold ~none:"" ~some:(fun ld -> "-fuse-ld=" ^ ld ^ " ") !Cmdline.use_linker)
           (if link_exe = `EXE then "" else "-shared ")
@@ -1338,13 +1346,17 @@ let remove_duplicate_paths paths =
 
 let setup_toolchain () =
   let mingw_libs pre =
-    gcc := pre ^ "gcc";
     objdump := pre ^ "objdump";
     let rec get_lib_search_dirs install libraries input =
       match input with
       | entry :: input ->
           if String.length entry > 9 && String.sub entry 0 9 = "install: " then
-            get_lib_search_dirs (String.sub entry 9 (String.length entry - 9)) libraries input
+            let install = String.sub entry 9 (String.length entry - 9) in
+            (* Ensure install does not end with a separator (or
+               [Sys.is_directory] will fail) *)
+            let install = Filename.concat install Filename.current_dir_name
+                          |> Filename.dirname in
+            get_lib_search_dirs (Some install) libraries input
           else begin try
             match split entry '=' with
             | "libraries: ", paths -> get_lib_search_dirs install paths input
@@ -1353,18 +1365,9 @@ let setup_toolchain () =
             get_lib_search_dirs install libraries input
           end
       | [] ->
-          let install =
-            if install <> "" then
-              (* Ensure install does not end with a separator (or
-                 Sys.is_directory will fail) *)
-              Filename.concat install Filename.current_dir_name
-              |> Filename.dirname
-            else
-              ""
-          in
           let separator, run_through_cygpath =
             if Sys.win32 then
-              if dir_exists_no_cygpath install then
+              if Option.fold ~none:true ~some:dir_exists_no_cygpath install then
                 ';', false
               else
                 ':', (!use_cygpath <> `No)
@@ -1378,13 +1381,14 @@ let setup_toolchain () =
             libraries
     in
     let lib_search_dirs =
-      get_lib_search_dirs "" "" (get_output "%s -print-search-dirs" !gcc)
+      get_lib_search_dirs None "" (get_output "%s -print-search-dirs" (cc !toolchain))
+      |> List.filter (( <> ) "")
       |> List.map normalize_path
       |> remove_duplicate_paths
     in
     search_path := !dirs @ lib_search_dirs;
     if !verbose >= 1 then begin
-      print_endline "lib search dirs:";
+      Printf.printf "lib search dirs (%s):\n" (cc !toolchain);
       List.iter (Printf.printf "  %s\n") lib_search_dirs;
       flush stdout
     end;
@@ -1410,14 +1414,13 @@ let setup_toolchain () =
       add_flexdll_obj := false;
       noentry := true
   | `CYGWIN64 ->
-      gcc := "gcc";
       objdump := "objdump";
       search_path :=
         !dirs @
           [
            "/lib";
            "/lib/w32api";
-           Filename.dirname (get_output1 ~use_bash:true "gcc -print-libgcc-file-name");
+           Filename.dirname (get_output1 ~use_bash:true "%s -print-libgcc-file-name" (cc !toolchain));
           ];
       default_libs := ["-lkernel32"; "-luser32"; "-ladvapi32";
                        "-lshell32"; "-lcygwin"; "-lgcc_s"; "-lgcc"]
@@ -1436,7 +1439,7 @@ let setup_toolchain () =
     search_path :=
       !dirs @
       [
-       Filename.dirname (get_output1 "%s -print-libgcc-file-name" !gcc);
+       Filename.dirname (get_output1 "%s -print-libgcc-file-name" (cc !toolchain));
        read_gnatls ();
       ];
     default_libs :=
@@ -1475,21 +1478,23 @@ let compile_if_needed file =
     let cmd = match !toolchain with
       | `MSVC | `MSVC64 ->
           Printf.sprintf
-            "cl /c /MD /nologo /Fo%s %s %s%s"
+            "%s /c /MD /nologo /Fo%s %s %s%s"
+            (cc !toolchain)
             (Filename.quote tmp_obj)
             (mk_dirs_opt "/I")
             file
             pipe
       | `CYGWIN64 ->
           Printf.sprintf
-            "gcc -c -o %s %s %s"
+            "%s -c -o %s %s %s"
+            (cc !toolchain)
             (Filename.quote tmp_obj)
             (mk_dirs_opt "-I")
             file
       | `MINGW | `MINGW64 | `GNAT | `GNAT64 ->
           Printf.sprintf
             "%s -c -o %s %s %s"
-            !gcc
+            (cc !toolchain)
             (Filename.quote tmp_obj)
             (mk_dirs_opt "-I")
             (Filename.quote file)