[clang] Add a flag to get around missing files in the buck integration

Reviewed By: jberdine

Differential Revision: D4946121

fbshipit-source-id: caac02c

infer/src/base/Config.ml

@@ -651,6 +651,13 @@ and clang_include_to_override_regex =
      location of internal compiler headers. This option should specify regular expression with \
      the path to those headers so that infer can use its own clang internal headers instead."
 
+and clang_ignore_regex =
+  CLOpt.mk_string_opt ~long:"clang-ignore-regex"
+    ~meta:"dir OCaml regex"
+    "The files in this regex will be ignored in the compilation process and \
+     an empty file will be passed to clang instead. This is to be used with the buck flavour \
+     infer-capture-all to work around missing generated files."
+
 and classpath =
   CLOpt.mk_string_opt ~long:"classpath"
     "Specify the Java classpath"
@@ -1629,6 +1636,7 @@ and dump_duplicate_symbols = !dump_duplicate_symbols
 and checkers = !checkers
 and checkers_repeated_calls = !checkers_repeated_calls
 and clang_biniou_file = !clang_biniou_file
+and clang_ignore_regex = !clang_ignore_regex
 and clang_include_to_override_regex = !clang_include_to_override_regex
 and classpath = !classpath
 and cluster_cmdline = !cluster

infer/src/base/Config.mli

@@ -197,6 +197,7 @@ val clang_biniou_file : string option
 val clang_frontend_action_string : string
 val clang_frontend_do_capture : bool
 val clang_frontend_do_lint : bool
+val clang_ignore_regex : string option
 val clang_include_to_override_regex : string option
 val cluster_cmdline : string option
 val compute_analytics : bool

infer/src/clang/ClangWrapper.re

@@ -17,6 +17,41 @@ type action_item =
   | ClangError string
   | ClangWarning string;
 
+let clang_ignore_regex = Option.map f::Str.regexp Config.clang_ignore_regex;
+
+let check_for_existing_file args =>
+  if (Option.is_some clang_ignore_regex && Option.is_none Config.buck_compilation_database) {
+    let (arg_files, args_list) = List.partition_tf f::(String.is_prefix prefix::"@") args;
+    let read_arg_files args_list arg_file_at => {
+      let file = String.slice arg_file_at 1 (String.length arg_file_at);
+      let args_list_file = In_channel.read_lines file;
+      List.append args_list args_list_file
+    };
+    let all_args_ = List.fold_left f::read_arg_files init::args_list arg_files;
+    let all_args = List.map f::String.strip all_args_;
+    let rec check_for_existing_file_arg args =>
+      switch args {
+      | [] => ()
+      | [option, ...rest] =>
+        if (String.equal option "-c") {
+          /* infer-capture-all flavour of buck produces path to generated file that doesn't exist.
+             Create empty file empty file and pass that to clang. This is to enable compilation to continue */
+          switch (clang_ignore_regex, List.hd rest) {
+          | (Some regexp, Some arg) =>
+            if (Str.string_match regexp arg 0 && Sys.file_exists arg != `Yes) {
+              Unix.mkdir_p (Filename.dirname arg);
+              let file = Unix.openfile mode::[Unix.O_CREAT, Unix.O_RDONLY] arg;
+              Unix.close file
+            }
+          | _ => ()
+          }
+        } else {
+          check_for_existing_file_arg rest
+        }
+      };
+    check_for_existing_file_arg all_args
+  };
+
 
 /** Given a list of arguments for clang [args], return a list of new commands to run according to
     the results of `clang -### [args]`. */
@@ -100,6 +135,7 @@ let exe ::prog ::args => {
   let xx_suffix = String.is_suffix suffix::"++" prog ? "++" : "";
   /* use clang in facebook-clang-plugins */
   let clang_xx = CFrontend_config.clang_bin xx_suffix;
+  check_for_existing_file args;
   let commands = normalize prog::clang_xx ::args;
   /* xcodebuild projects may require the object files to be generated by the Apple compiler, eg to
      generate precompiled headers compatible with Apple's clang. */