[gnumeric] GUI: Use shortest round-tripping versions for constants in formulae.

[Morten Welinder <mortenw src gnome org>]

commit 4a112f1eb3a48e0e4b98bbb04bafaf835f90a8f9
Author: Morten Welinder <terra gnome org>
Date:   Sun Aug 21 15:59:17 2016 -0400

    GUI: Use shortest round-tripping versions for constants in formulae.

 ChangeLog        |    5 +++++
 src/parse-util.c |    2 +-
 src/value.c      |    9 ++++++---
 3 files changed, 12 insertions(+), 4 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index 115ae93..7d88bdf 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2016-08-21  Morten Welinder  <terra gnome org>
+
+       * src/value.c (value_get_as_gstring): Let a negative
+       decimal_digits mean "shortest round-tripping string".
+
 2016-08-20  Morten Welinder <terra gnome org>
 
        * configure.ac: Post-release bump.
diff --git a/src/parse-util.c b/src/parse-util.c
index f9cb11f..45d0f4f 100644
--- a/src/parse-util.c
+++ b/src/parse-util.c
@@ -1475,7 +1475,7 @@ gnm_conventions_new_full (unsigned size)
        convs->input.func               = std_func_map;
        convs->input.external_wb        = std_external_wb;
 
-       convs->output.decimal_digits    = GNM_DIG;
+       convs->output.decimal_digits    = -1;
        convs->output.translated        = TRUE;
        convs->output.string            = std_output_string;
        convs->output.name              = std_expr_name_handler;
diff --git a/src/value.c b/src/value.c
index 9f52201..d1b0daf 100644
--- a/src/value.c
+++ b/src/value.c
@@ -924,9 +924,12 @@ value_get_as_gstring (GnmValue const *v, GString *target,
                return;
 
        case VALUE_FLOAT:
-               g_string_append_printf (target, "%.*" GNM_FORMAT_g,
-                                       conv->output.decimal_digits,
-                                       v->v_float.val);
+               if (conv->output.decimal_digits < 0)
+                       go_dtoa (target, "!" GNM_FORMAT_g, v->v_float.val);
+               else
+                       g_string_append_printf (target, "%.*" GNM_FORMAT_g,
+                                               conv->output.decimal_digits,
+                                               v->v_float.val);
                return;
 
        case VALUE_ARRAY: {