output: do not generate source files when late errors are caught

Reported by Alexandre Duret-Lutz as "second problem" in:
http://lists.gnu.org/archive/html/bug-bison/2013-09/msg00015.html

* bootstrap.conf: We need the "unlink" module.
* src/files.h, src/files.c (unlink_generated_sources): New.
* src/output.c: Use it.
* tests/output.at: Check the case of late errors.

bootstrap.conf

@@ -34,7 +34,8 @@ gnulib_modules='
   readme-release
   realloc-posix
   spawn-pipe stdbool stpcpy strdup-posix strerror strtoul strverscmp
-  unistd unistd-safer unlocked-io update-copyright unsetenv verify
+  unistd unistd-safer unlink unlocked-io
+  update-copyright unsetenv verify
   warnings
   xalloc
   xalloc-die

src/files.c

@@ -398,6 +398,16 @@ output_file_name_check (char **file_name, bool source)
     }
 }
 
+void
+unlink_generated_sources (void)
+{
+  int i;
+  for (i = 0; i < generated_files_size; i++)
+    if (generated_files[i].is_source)
+      /* Ignore errors.  The file might not even exist.  */
+      unlink (generated_files[i].name);
+}
+
 void
 output_file_names_free (void)
 {

src/files.h

@@ -70,6 +70,9 @@ void output_file_names_free (void);
  */
 void output_file_name_check (char **file_name, bool source);
 
+/** Remove all the generated source files. */
+void unlink_generated_sources (void);
+
 FILE *xfopen (const char *name, char const *mode);
 void xfclose (FILE *ptr);
 FILE *xfdopen (int fd, char const *mode);

src/output.c

@@ -704,6 +704,11 @@ output (void)
   /* Process the selected skeleton file.  */
   output_skeleton ();
 
+  /* If late errors were generated, destroy the generated source
+     files. */
+  if (complaint_status)
+    unlink_generated_sources ();
+
   obstack_free (&format_obstack, NULL);
 }
 

tests/output.at

@@ -43,7 +43,7 @@ done
 ]AT_DATA([$1],
 [$2[
 %%
-foo: {};
+foo: %empty {};
 ]])[
 
 ]AT_BISON_CHECK([$3 $1], [$5], [], [ignore])[
@@ -126,6 +126,14 @@ AT_CHECK_OUTPUT([foo.y], [%type <foo> useless],
                 [foo.dot foo.output foo.xml],
                 [1])
 
+# Do not generate code when there are late errors (even warnings as
+# errors).
+AT_CHECK_OUTPUT([foo.y], [%define useless],
+                [--defines --graph --xml --report=all -Wall -Werror],
+                [foo.dot foo.output foo.xml],
+                [1])
+
+
 ## ------------ ##
 ## C++ output.  ##
 ## ------------ ##