preprocessor: main file searching

This adds the capability to locate the main file on the user or system
include paths.  That's extremely useful to users building header
units.  Searching has to be requiested (plain header-unit compilation
will not search).  Also, to make include_next work as expected when
building a header unit, we add a mechanism to retrofit a non-searched
source file as one on the include path.

	libcpp/
	* include/cpplib.h (enum cpp_main_search): New.
	(struct cpp_options): Add main_search field.
	(cpp_main_loc): Declare.
	(cpp_retrofit_as_include): Declare.
	* internal.h (struct cpp_reader): Add main_loc field.
	(_cpp_in_main_source_file): Not main if main is a header.
	* init.c (cpp_read_main_file): Use main_search option to locate
	main file.  Set main_loc
	* files.c (cpp_retrofit_as_include): New.

diff --git a/libcpp/files.c b/libcpp/files.c
index ba52d2bf3cf1c17e603e1179e5fbf8a9b27777eb..301b2379a23966a2ef348375fd6fe750551cc66b 100644 (file)
--- a/libcpp/files.c
+++ b/libcpp/files.c
@@ -1131,6 +1131,37 @@ cpp_find_header_unit (cpp_reader *pfile, const char *name, bool angle,
   return file->path;
 }
 
+/* Retrofit the just-entered main file asif it was an include.  This
+   will permit correct include_next use, and mark it as a system
+   header if that's where it resides.  We use filesystem-appropriate
+   prefix matching of the include path to locate the main file.  */
+void
+cpp_retrofit_as_include (cpp_reader *pfile)
+{
+  /* We should be the outermost.  */
+  gcc_assert (!pfile->buffer->prev);
+
+  if (const char *name = pfile->main_file->name)
+    {
+      /* Locate name on the include dir path, using a prefix match.  */
+      size_t name_len = strlen (name);
+      for (cpp_dir *dir = pfile->quote_include; dir; dir = dir->next)
+       if (dir->len < name_len
+           && IS_DIR_SEPARATOR (name[dir->len])
+           && !filename_ncmp (name, dir->name, dir->len))
+         {
+           pfile->main_file->dir = dir;
+           if (dir->sysp)
+             cpp_make_system_header (pfile, 1, 0);
+           break;
+         }
+    }
+
+  /* Initialize controlling macro state.  */
+  pfile->mi_valid = true;
+  pfile->mi_cmacro = 0;
+}
+
 /* Could not open FILE.  The complication is dependency output.  */
 static void
 open_file_failed (cpp_reader *pfile, _cpp_file *file, int angle_brackets,

diff --git a/libcpp/include/cpplib.h b/libcpp/include/cpplib.h
index 630f2e055d129536e21813f701dd265f778382ba..91226cfc248d71b3fe77f97c96e754bd3aec6311 100644 (file)
--- a/libcpp/include/cpplib.h
+++ b/libcpp/include/cpplib.h
@@ -308,6 +308,15 @@ enum cpp_normalize_level {
   normalized_none
 };
 
+enum cpp_main_search 
+{
+  CMS_none,    /* A regular source file.  */
+  CMS_header,  /* Is a directly-specified header file (eg PCH or
+                 header-unit).  */
+  CMS_user,    /* Search the user INCLUDE path.  */
+  CMS_system,  /* Search the system INCLUDE path.  */
+};
+
 /* This structure is nested inside struct cpp_reader, and
    carries all the options visible to the command line.  */
 struct cpp_options
@@ -566,6 +575,8 @@ struct cpp_options
 
   /* The maximum depth of the nested #include.  */
   unsigned int max_include_depth;
+
+  cpp_main_search main_search : 8;
 };
 
 /* Diagnostic levels.  To get a diagnostic without associating a
@@ -997,6 +1008,10 @@ extern const char *cpp_find_header_unit (cpp_reader *, const char *file,
    too.  If there was an error opening the file, it returns NULL.  */
 extern const char *cpp_read_main_file (cpp_reader *, const char *,
                                       bool injecting = false);
+extern location_t cpp_main_loc (const cpp_reader *);
+
+/* Adjust for the main file to be an include.  */
+extern void cpp_retrofit_as_include (cpp_reader *);
 
 /* Set up built-ins with special behavior.  Use cpp_init_builtins()
    instead unless your know what you are doing.  */

diff --git a/libcpp/init.c b/libcpp/init.c
index fc826583d3a1199dc0bdc7547ba9aede6375a582..f77dc26a003dc784c2b1585353681ee992ce7a0b 100644 (file)
--- a/libcpp/init.c
+++ b/libcpp/init.c
@@ -675,8 +675,14 @@ cpp_read_main_file (cpp_reader *pfile, const char *fname, bool injecting)
     deps_add_default_target (deps, fname);
 
   pfile->main_file
-    = _cpp_find_file (pfile, fname, &pfile->no_search_path, /*angle=*/0,
-                     _cpp_FFK_NORMAL, 0);
+    = _cpp_find_file (pfile, fname,
+                     CPP_OPTION (pfile, preprocessed) ? &pfile->no_search_path
+                     : CPP_OPTION (pfile, main_search) == CMS_user
+                     ? pfile->quote_include
+                     : CPP_OPTION (pfile, main_search) == CMS_system
+                     ? pfile->bracket_include : &pfile->no_search_path,
+                     /*angle=*/0, _cpp_FFK_NORMAL, 0);
+
   if (_cpp_find_failed (pfile->main_file))
     return NULL;
 
@@ -698,7 +704,16 @@ cpp_read_main_file (cpp_reader *pfile, const char *fname, bool injecting)
                             LINEMAP_LINE (last), LINEMAP_SYSP (last));
       }
 
-  return ORDINARY_MAP_FILE_NAME (LINEMAPS_LAST_ORDINARY_MAP (pfile->line_table));
+  auto *map = LINEMAPS_LAST_ORDINARY_MAP (pfile->line_table);
+  pfile->main_loc = MAP_START_LOCATION (map);
+
+  return ORDINARY_MAP_FILE_NAME (map);
+}
+
+location_t
+cpp_main_loc (const cpp_reader *pfile)
+{
+  return pfile->main_loc;
 }
 
 /* For preprocessed files, if the very first characters are

diff --git a/libcpp/internal.h b/libcpp/internal.h
index e629cbca26ae12e4bef5ca6f946e6fb1b167b5a2..697fef053ba5d126d4953768239cd34cca2a6498 100644 (file)
--- a/libcpp/internal.h
+++ b/libcpp/internal.h
@@ -591,6 +591,10 @@ struct cpp_reader
   /* If non-zero, the lexer will use this location for the next token
      instead of getting a location from the linemap.  */
   location_t forced_token_location;
+
+  /* Location identifying the main source file -- intended to be line
+     zero of said file.  */
+  location_t main_loc;
 };
 
 /* Character classes.  Based on the more primitive macros in safe-ctype.h.
@@ -643,7 +647,8 @@ _cpp_in_system_header (cpp_reader *pfile)
 inline int
 _cpp_in_main_source_file (cpp_reader *pfile)
 {
-  return pfile->buffer->file == pfile->main_file;
+  return (!CPP_OPTION (pfile, main_search)
+         && pfile->buffer->file == pfile->main_file);
 }
 
 /* True if NODE is a macro for the purposes of ifdef, defined etc.  */