Add feature patch for -tpg/-ntpg.

This switch enables using Postgres' rules for using tabs vs spaces
in indents, to match the output of our old "entab" program.
The FreeBSD maintainer wants no part of this, so we'll have to carry
this as a forked patch.  (The alternative is to go over to use-tabs-
whenever-possible rules, but that would result in circa 10K lines of
invisible whitespace diffs in the PG sources, which seems like lots
more pain than is justified.)

5 files changed, 18 insertions, 2 deletions

diff --git a/args.c b/args.c
index 73d8121..f79de75 100644
--- a/args.c
+++ b/args.c
@@ -154,6 +154,7 @@ struct pro {
     {"nsac", PRO_BOOL, false, OFF, &space_after_cast},
     {"nsc", PRO_BOOL, true, OFF, &star_comment_cont},
     {"nsob", PRO_BOOL, false, OFF, &swallow_optional_blanklines},
+    {"ntpg", PRO_BOOL, false, OFF, &postgres_tab_rules},
     {"nut", PRO_BOOL, true, OFF, &use_tabs},
     {"nv", PRO_BOOL, false, OFF, &verbose},
     {"pcs", PRO_BOOL, false, ON, &proc_calls_space},
@@ -163,6 +164,7 @@ struct pro {
     {"sob", PRO_BOOL, false, ON, &swallow_optional_blanklines},
     {"st", PRO_SPECIAL, 0, STDIN, 0},
     {"ta", PRO_BOOL, false, ON, &auto_typedefs},
+    {"tpg", PRO_BOOL, false, ON, &postgres_tab_rules},
     {"ts", PRO_INT, 8, 0, &tabsize},
     {"ut", PRO_BOOL, true, ON, &use_tabs},
     {"v", PRO_BOOL, false, ON, &verbose},
diff --git a/indent.1 b/indent.1
index 0a6ef06..131abfe 100644
--- a/indent.1
+++ b/indent.1
@@ -87,6 +87,7 @@
 .Op Fl \&st
 .Op Fl \&ta
 .Op Fl T Ns Ar typename
+.Op Fl tpg | Fl ntpg
 .Op Fl ts Ns Ar n
 .Op Fl U Ns Ar file
 .Op Fl ut | Fl nut
@@ -472,6 +473,14 @@ language and
 cannot find all
 instances of
 .Ic typedef .
+.It Fl tpg , ntpg
+If
+.Fl tpg
+is specified, follow Postgres rules about when to use spaces versus
+tabs for indentation, that is, use a space instead of a tab if the
+tab would move only one column and no tab will follow it.
+Default:
+.Fl ntpg .
 .It Fl ts Ns Ar n
 Assumed distance between tab stops.
 The default is 8.
diff --git a/indent.c b/indent.c
index d01d722..e6560af 100644
--- a/indent.c
+++ b/indent.c
@@ -1251,7 +1251,9 @@ indent_declaration(int cur_dec_ind, int tabs_to_var)
 
 	CHECK_SIZE_CODE(cur_dec_ind / tabsize);
 	while ((tpos = tabsize * (1 + pos / tabsize)) <= cur_dec_ind) {
-	    *e_code++ = '\t';
+	    *e_code++ = (!postgres_tab_rules ||
+			 tpos != pos + 1 ||
+			 cur_dec_ind >= tpos + tabsize) ? '\t' : ' ';
 	    pos = tpos;
 	}
     }
diff --git a/indent_globs.h b/indent_globs.h
index ade80e5..d018af1 100644
--- a/indent_globs.h
+++ b/indent_globs.h
@@ -220,6 +220,7 @@ int	    use_tabs;			/* set true to use tabs for spacing,
 int	    auto_typedefs;		/* set true to recognize identifiers
 					 * ending in "_t" like typedefs */
 int	    space_after_cast;		/* "b = (int) a" vs "b = (int)a" */
+int	    postgres_tab_rules;		/* use Postgres tab-vs-space rules */
 int	    tabsize;			/* the size of a tab */
 int	    else_endif_com_ind;		/* the column in which comments to
 					 * the right of #else and #endif
diff --git a/io.c b/io.c
index 0792df0..df11094 100644
--- a/io.c
+++ b/io.c
@@ -401,7 +401,9 @@ pad_output(int current, int target)
 	int tcur;
 
 	while ((tcur = tabsize * (1 + (curr - 1) / tabsize) + 1) <= target) {
-	    putc('\t', output);
+	    putc((!postgres_tab_rules ||
+		  tcur != curr + 1 ||
+		  target >= tcur + tabsize) ? '\t' : ' ', output);
 	    curr = tcur;
 	}
     }