[PATCH v6 4/4] c++modules: report module mapper files as a dependency

[Ben Boeckel <ben.boeckel@kitware.com>]

It affects the build, and if used as a static file, can reliably be
tracked using the `-MF` mechanism.

gcc/cp/:

	* mapper-client.cc, mapper-client.h (open_module_client): Accept
	dependency tracking and track module mapper files as
	dependencies.
	* module.cc (make_mapper, get_mapper): Pass the dependency
	tracking class down.

Signed-off-by: Ben Boeckel <ben.boeckel@kitware.com>
---
 gcc/cp/mapper-client.cc |  4 ++++
 gcc/cp/mapper-client.h  |  1 +
 gcc/cp/module.cc        | 18 +++++++++---------
 3 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/gcc/cp/mapper-client.cc b/gcc/cp/mapper-client.cc
index 39e80df2d25..0ce5679d659 100644
--- a/gcc/cp/mapper-client.cc
+++ b/gcc/cp/mapper-client.cc
@@ -34,6 +34,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "diagnostic-core.h"
 #include "mapper-client.h"
 #include "intl.h"
+#include "mkdeps.h"
 
 #include "../../c++tools/resolver.h"
 
@@ -132,6 +133,7 @@ spawn_mapper_program (char const **errmsg, std::string &name,
 
 module_client *
 module_client::open_module_client (location_t loc, const char *o,
+				   class mkdeps *deps,
 				   void (*set_repo) (const char *),
 				   char const *full_program_name)
 {
@@ -285,6 +287,8 @@ module_client::open_module_client (location_t loc, const char *o,
 	  errmsg = "opening";
 	else
 	  {
+	    /* Add the mapper file to the dependency tracking. */
+	    deps_add_dep (deps, name.c_str ());
 	    if (int l = r->read_tuple_file (fd, ident, false))
 	      {
 		if (l > 0)
diff --git a/gcc/cp/mapper-client.h b/gcc/cp/mapper-client.h
index b32723ce296..a3b0b8adc51 100644
--- a/gcc/cp/mapper-client.h
+++ b/gcc/cp/mapper-client.h
@@ -55,6 +55,7 @@ public:
 
 public:
   static module_client *open_module_client (location_t loc, const char *option,
+					    class mkdeps *,
 					    void (*set_repo) (const char *),
 					    char const *);
   static void close_module_client (location_t loc, module_client *);
diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc
index e88ce0a1818..9dbb53d2aaf 100644
--- a/gcc/cp/module.cc
+++ b/gcc/cp/module.cc
@@ -3969,12 +3969,12 @@ static GTY(()) vec<tree, va_gc> *partial_specializations;
 /* Our module mapper (created lazily).  */
 module_client *mapper;
 
-static module_client *make_mapper (location_t loc);
-inline module_client *get_mapper (location_t loc)
+static module_client *make_mapper (location_t loc, class mkdeps *deps);
+inline module_client *get_mapper (location_t loc, class mkdeps *deps)
 {
   auto *res = mapper;
   if (!res)
-    res = make_mapper (loc);
+    res = make_mapper (loc, deps);
   return res;
 }
 
@@ -14031,7 +14031,7 @@ get_module (const char *ptr)
 /* Create a new mapper connecting to OPTION.  */
 
 module_client *
-make_mapper (location_t loc)
+make_mapper (location_t loc, class mkdeps *deps)
 {
   timevar_start (TV_MODULE_MAPPER);
   const char *option = module_mapper_name;
@@ -14039,7 +14039,7 @@ make_mapper (location_t loc)
     option = getenv ("CXX_MODULE_MAPPER");
 
   mapper = module_client::open_module_client
-    (loc, option, &set_cmi_repo,
+    (loc, option, deps, &set_cmi_repo,
      (save_decoded_options[0].opt_index == OPT_SPECIAL_program_name)
      && save_decoded_options[0].arg != progname
      ? save_decoded_options[0].arg : nullptr);
@@ -19504,7 +19504,7 @@ maybe_translate_include (cpp_reader *reader, line_maps *lmaps, location_t loc,
   dump.push (NULL);
 
   dump () && dump ("Checking include translation '%s'", path);
-  auto *mapper = get_mapper (cpp_main_loc (reader));
+  auto *mapper = get_mapper (cpp_main_loc (reader), cpp_get_deps (reader));
 
   size_t len = strlen (path);
   path = canonicalize_header_name (NULL, loc, true, path, len);
@@ -19620,7 +19620,7 @@ module_begin_main_file (cpp_reader *reader, line_maps *lmaps,
 static void
 name_pending_imports (cpp_reader *reader)
 {
-  auto *mapper = get_mapper (cpp_main_loc (reader));
+  auto *mapper = get_mapper (cpp_main_loc (reader), cpp_get_deps (reader));
 
   if (!vec_safe_length (pending_imports))
     /* Not doing anything.  */
@@ -20090,7 +20090,7 @@ init_modules (cpp_reader *reader)
 
   if (!flag_module_lazy)
     /* Get the mapper now, if we're not being lazy.  */
-    get_mapper (cpp_main_loc (reader));
+    get_mapper (cpp_main_loc (reader), cpp_get_deps (reader));
 
   if (!flag_preprocess_only)
     {
@@ -20300,7 +20300,7 @@ late_finish_module (cpp_reader *reader,  module_processing_cookie *cookie,
 
   if (!errorcount)
     {
-      auto *mapper = get_mapper (cpp_main_loc (reader));
+      auto *mapper = get_mapper (cpp_main_loc (reader), cpp_get_deps (reader));
       mapper->ModuleCompiled (state->get_flatname ());
     }
   else if (cookie->cmi_name)
-- 
2.40.1