Make infer binary runnable on Mojave without fiddling with SDKROOT

Summary:
TL;DR: Until this patch, if you ran infer on MacOS Mojave you most
likely would get an error related to missing header files. Now infer
tries to automatically locate current MacOS SDK path thus providing a
better experience for first time users.

Consider helloworld.c
```
#include <stdio.h>
int main()
{
	return 0;
}
```
Invoking the analysis `infer -- cc -c helloworld.c` fails with

facebook-clang-plugins/.../include/c++/v1/stdio.h:108:15: fatal error: 'stdio.h' file not found

The reason for this is twofold:
1. infer uses its own clang, not Apple's one (thus custom paths are
not properly setup).
2. Apple stopped copying standard headers from SDK to /usr/include.

Reviewed By: jvillard

Differential Revision: D16377866

fbshipit-source-id: c336ad64f

Makefile.autoconf.in

@@ -11,6 +11,7 @@ bindir = @bindir@
 BUCK = @BUCK@
 BUILD_C_ANALYZERS = @BUILD_C_ANALYZERS@
 BUILD_JAVA_ANALYZERS = @BUILD_JAVA_ANALYZERS@
+BUILD_PLATFORM = @BUILD_PLATFORM@
 CAML_LD_LIBRARY_PATH = @CAML_LD_LIBRARY_PATH@
 CC = @CC@
 CFLAGS = @CFLAGS@

configure.ac

@@ -49,16 +49,37 @@ AS_IF([test "x$CLANG_INCLUDES" = "x"], [
   CLANG_INCLUDES="$CLANG_PREFIX/include"
 ])
 
-windows_build=no
-AC_MSG_CHECKING([for Windows build])
+BUILD_PLATFORM=unknown
+WINDOWS_BUILD=no
+AC_MSG_CHECKING([for build platform])
 # see https://stackoverflow.com/questions/714100/os-detecting-makefile
 # but we do this in the configure for homogeneity
 case "${OS}" in
     Windows_NT*)
-        windows_build=yes
+        BUILD_PLATFORM=Windows
         ;;
+    *)
+        uname_str=`uname -s`
+        case "${uname_str}" in
+            Linux*)
+                BUILD_PLATFORM=Linux
+                ;;
+            Darwin*)
+                BUILD_PLATFORM=Darwin
+                ;;
+            cygwin*|mingw*)
+                BUILD_PLATFORM=Windows
+                ;;
+            *)
+                AC_MSG_ERROR(["OS $unamestr is not supported"])
+                ;;
+        esac
 esac
-WINDOWS_BUILD=$windows_build
+AC_MSG_RESULT([$BUILD_PLATFORM])
+AC_SUBST([BUILD_PLATFORM])
+
+AC_MSG_CHECKING([for Windows build])
+AS_IF([test x"$BUILD_PLATFORM" = x"Windows"], [WINDOWS_BUILD=yes])
 AC_MSG_RESULT([$WINDOWS_BUILD])
 AC_SUBST([WINDOWS_BUILD])
 

infer/src/Makefile

@@ -267,6 +267,7 @@ $(GENERATED_FROM_AUTOCONF): $(MAKEFILE_LIST)
 	  -e "s|@JDK11_ENABLED[@]|$(JDK11_ENABLED)|g" \
 	  -e "s|@BUILD_C_ANALYZERS[@]|$(BUILD_C_ANALYZERS)|g" \
 	  -e "s|@BUILD_JAVA_ANALYZERS[@]|$(BUILD_JAVA_ANALYZERS)|g" \
+	  -e "s|@BUILD_PLATFORM[@]|$(BUILD_PLATFORM)|g" \
 	  -e "s|@OPAMSWITCH[@]|$(OPAMSWITCH)|g" \
 	  -e "s|@XCODE_SELECT[@]|$(XCODE_SELECT)|g" \
 	  -e "s|@INFER_MAN_LAST_MODIFIED[@]|$(INFER_MAN_LAST_MODIFIED)|g" \

infer/src/base/Config.ml

@@ -448,6 +448,45 @@ let env_inside_maven = `Extend [(infer_inside_maven_env_var, "1")]
 
 let infer_is_javac = maven
 
+let locate_sdk_root () =
+  match Version.build_platform with
+  | Darwin -> (
+      let cmd = "xcrun --show-sdk-path --sdk macosx 2> /dev/null" in
+      try
+        let path, _ = Utils.with_process_in cmd In_channel.input_line in
+        path
+      with Unix.Unix_error _ -> None )
+  | _ ->
+      None
+
+
+let infer_sdkroot_env_var = "INFER_SDKROOT"
+
+(** Try to locate current SDK root on MacOS *unless* [SDKROOT] is
+   explicitly provided. The implicit SDK root is propagated to child
+   processes using a custom [INFER_SDKROOT] env var. The reason for
+   this is twofold:
+
+   1. With make and buck integrations infer is exec'ed by make/buck
+   for each source file. That's why we propagate the value by using an
+   env var instead of calling [locate_sdk_root] each time.
+
+   2. We don't use [SDKROOT] because it can mess up with other parts
+   of the toolchain not owned by infer. *)
+let implicit_sdk_root =
+  match Sys.getenv "SDKROOT" with
+  | Some _ ->
+      None
+  | None -> (
+    match Sys.getenv infer_sdkroot_env_var with
+    | Some _ as path ->
+        path
+    | None ->
+        let maybe_root = locate_sdk_root () in
+        let putenv x = Unix.putenv ~key:infer_sdkroot_env_var ~data:x in
+        Option.iter ~f:putenv maybe_root ; maybe_root )
+
+
 let startup_action =
   let open CLOpt in
   if infer_is_javac then Javac

infer/src/base/Config.mli

@@ -411,6 +411,8 @@ val infer_is_clang : bool
 
 val infer_is_javac : bool
 
+val implicit_sdk_root : string option
+
 val inferconfig_file : string option
 
 val iphoneos_target_sdk_version : string option

infer/src/base/Version.ml.in

@@ -22,6 +22,10 @@ let commit = "@INFER_GIT_COMMIT@"
 
 let branch = "@INFER_GIT_BRANCH@"
 
+type build_platform = Linux | Darwin | Windows
+
+let build_platform = @BUILD_PLATFORM@
+
 let is_release = is_yes "@IS_RELEASE_TREE@"
 
 let tag = Printf.sprintf "v%d.%d.%d" major minor patch

infer/src/base/Version.mli

@@ -15,6 +15,10 @@ val patch : int
 
 val commit : string
 
+type build_platform = Linux | Darwin | Windows
+
+val build_platform : build_platform
+
 val versionString : string
 
 val versionJson : string

infer/src/clang/ClangCommand.ml

@@ -85,7 +85,7 @@ let libcxx_include_to_override_regex =
 (** Filter arguments from [args], looking into argfiles too. [replace_options_arg prev arg] returns
    [arg'], where [arg'] is the new version of [arg] given the preceding arguments (in reverse order) [prev]. *)
 let filter_and_replace_unsupported_args ?(replace_options_arg = fun _ s -> s) ?(post_args = [])
-    args =
+    ?(pre_args = []) args =
   (* [prev] is the previously seen argument, [res_rev] is the reversed result, [changed] is true if
      some change has been performed *)
   let rec aux in_argfiles (prev_is_blacklisted_with_arg, res_rev, changed) args =
@@ -141,7 +141,7 @@ let filter_and_replace_unsupported_args ?(replace_options_arg = fun _ s -> s) ?(
   match aux String.Set.empty (false, [], false) args with
   | _, res_rev, _ ->
       (* return non-reversed list *)
-      List.rev_append res_rev post_args
+      List.append pre_args (List.rev_append res_rev post_args)
 
 
 (** Work around various path or library issues occurring when one tries to substitute Apple's version
@@ -181,6 +181,17 @@ let clang_cc1_cmd_sanitizer cmd =
   let args_defines =
     if Config.bufferoverrun && not Config.biabduction then ["-D__INFER_BUFFEROVERRUN"] else []
   in
+  let explicit_sysroot_passed = has_flag cmd "-isysroot" in
+  (* supply isysroot only when SDKROOT is not set up and explicit isysroot is not provided,
+     cf. https://lists.apple.com/archives/xcode-users/2005/Dec/msg00524.html
+     for details on the effects of setting SDKROOT *)
+  let implicit_sysroot =
+    if not explicit_sysroot_passed then
+      Option.map Config.implicit_sdk_root ~f:(fun x -> ["-isysroot"; x])
+      |> Option.value ~default:[]
+    else []
+  in
+  let pre_args_rev = [] |> List.rev_append implicit_sysroot in
   let post_args_rev =
     []
     |> List.rev_append ["-include"; Config.lib_dir ^/ "clang_wrappers" ^/ "global_defines.h"]
@@ -193,7 +204,7 @@ let clang_cc1_cmd_sanitizer cmd =
   in
   let clang_arguments =
     filter_and_replace_unsupported_args ~replace_options_arg ~post_args:(List.rev post_args_rev)
-      cmd.argv
+      ~pre_args:(List.rev pre_args_rev) cmd.argv
   in
   file_arg_cmd_sanitizer {cmd with argv= clang_arguments}