From 5ec9c996628f5340f6fa1daba7f49ab3c2ea4872 Mon Sep 17 00:00:00 2001
From: Akim Demaille <akim.demaille@gmail.com>
Date: Mon, 21 Jan 2019 19:37:10 +0100
Subject: [PATCH] --update: when used, do not generate the output files

It is inconvenient that we also generate the output files when we
update the grammar file, and it's somewhat unexpected.  Let's not do
that.

* src/main.c (main): Skip generation when --update is passed.
* src/getargs.c (usage): Update the help message.
* doc/bison.texi (Bison Options): Likewise.
* tests/input.at: Check that we don't generate the output.
---
 doc/bison.texi |  4 ++--
 src/getargs.c  |  2 +-
 src/main.c     | 56 ++++++++++++++++++++++++++++----------------------
 tests/input.at | 11 +++++++---
 4 files changed, 42 insertions(+), 31 deletions(-)

diff --git a/doc/bison.texi b/doc/bison.texi
index c31e851b..884a7bd8 100644
--- a/doc/bison.texi
+++ b/doc/bison.texi
@@ -10272,8 +10272,8 @@ Print the name of the directory containing skeletons and XSLT.
 @item -u
 @item --update
 Update the grammar file (remove duplicates, update deprecated directives,
-etc.).  Leaves a backup of the original file with a @code{~} appended.  For
-instance:
+etc.) and exit (i.e., do not generate any of the output files).  Leaves a
+backup of the original file with a @code{~} appended.  For instance:
 
 @example
 @group
diff --git a/src/getargs.c b/src/getargs.c
index a66e4c66..95572681 100644
--- a/src/getargs.c
+++ b/src/getargs.c
@@ -287,7 +287,7 @@ Operation modes:\n\
                              and exit\n\
       --print-datadir        output directory containing skeletons and XSLT\n\
                              and exit\n\
-  -u, --update               apply fixes to the source grammar file\n\
+  -u, --update               apply fixes to the source grammar file and exit\n\
   -y, --yacc                 emulate POSIX Yacc\n\
   -W, --warnings[=CATEGORY]  report the warnings falling in CATEGORY\n\
   -f, --feature[=FEATURE]    activate miscellaneous features\n\
diff --git a/src/main.c b/src/main.c
index 10a07d2e..0fbbca05 100644
--- a/src/main.c
+++ b/src/main.c
@@ -155,31 +155,34 @@ main (int argc, char *argv[])
 
   print_precedence_warnings ();
 
-  /* Output file names. */
-  compute_output_file_names ();
-
-  /* Output the detailed report on the grammar.  */
-  if (report_flag)
+  if (!update_flag)
     {
-      timevar_push (tv_report);
-      print_results ();
-      timevar_pop (tv_report);
-    }
+      /* Output file names. */
+      compute_output_file_names ();
 
-  /* Output the graph.  */
-  if (graph_flag)
-    {
-      timevar_push (tv_graph);
-      print_graph ();
-      timevar_pop (tv_graph);
-    }
+      /* Output the detailed report on the grammar.  */
+      if (report_flag)
+        {
+          timevar_push (tv_report);
+          print_results ();
+          timevar_pop (tv_report);
+        }
 
-  /* Output xml.  */
-  if (xml_flag)
-    {
-      timevar_push (tv_xml);
-      print_xml ();
-      timevar_pop (tv_xml);
+      /* Output the graph.  */
+      if (graph_flag)
+        {
+          timevar_push (tv_graph);
+          print_graph ();
+          timevar_pop (tv_graph);
+        }
+
+      /* Output xml.  */
+      if (xml_flag)
+        {
+          timevar_push (tv_xml);
+          print_xml ();
+          timevar_pop (tv_xml);
+        }
     }
 
   /* Stop if there were errors, to avoid trashing previous output
@@ -193,9 +196,12 @@ main (int argc, char *argv[])
   timevar_pop (tv_free);
 
   /* Output the tables and the parser to ftable.  In file output.  */
-  timevar_push (tv_parser);
-  output ();
-  timevar_pop (tv_parser);
+  if (!update_flag)
+    {
+      timevar_push (tv_parser);
+      output ();
+      timevar_pop (tv_parser);
+    }
 
   timevar_push (tv_free);
   nullable_free ();
diff --git a/tests/input.at b/tests/input.at
index 11f02ce5..8853af51 100644
--- a/tests/input.at
+++ b/tests/input.at
@@ -2500,7 +2500,7 @@ AT_DATA_GRAMMAR([[input.y]],
 %no-default_prec
 %no_default-prec
 %no_lines
-%output = "foo"
+%output = "output.c"
 %pure_parser
 %token_table
 %error-verbose
@@ -2559,7 +2559,9 @@ AT_BISON_CHECK([[-ffixit input.y]], [], [], [experr])
 AT_CHECK([[sed -e '/^fix-it:/d' errors-all >experr]])
 AT_BISON_CHECK([[input.y]], [], [], [experr])
 
-# Update the input file.
+
+# Update the input file.  Make sure we generated nothing.
+AT_CHECK([rm -f output.c])
 AT_CHECK([cp input.y input.y.orig])
 AT_CHECK([sed -e '/fix-it/d' <errors-all >experr])
 AT_CHECK([echo "bison: file 'input.y' was updated (backup: 'input.y~')" >>experr])
@@ -2568,6 +2570,9 @@ AT_BISON_CHECK([[--update input.y]], [], [[]], [experr])
 # Check the backup.
 AT_CHECK([diff input.y.orig input.y~])
 
+# Check we did not generate any file.
+AT_CHECK([test ! -f output.c])
+
 # Check the update.
 AT_CHECK([cat input.y], [],
 [[%code top {
@@ -2588,7 +2593,7 @@ AT_CHECK([cat input.y], [],
 %no-default-prec
 %no-default-prec
 %no-lines
-%output "foo"
+%output "output.c"
 %pure-parser
 %token-table
 %glr-parser