I suggest that we add the gcc (also clang) option -ftabstop=4.
This has two effects: First, it produces more accurate column numbers
in compiler errors and correctly indents the code excerpts that the
compiler shows with those. Second, it enables the compiler's detection
of confusingly indented code to work more correctly. (But the latter is
only a potential problem for code that does not use tabs for
indentation, so it would be mostly a help during development with sloppy
editor setups.)
Attached is a patch to discover the option in configure.
One bit of trickery not addressed yet is that we might want to strip out
the option and not expose it through PGXS, since we don't know what
whitespacing rules external code uses.
Thoughts?
From 2095d1616b2ba8e39daa6aac8004936b8a229354 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <pe...@eisentraut.org>
Date: Tue, 21 Jun 2022 12:40:59 +0200
Subject: [PATCH] Add compiler option -ftabstop=4 if available
---
configure | 43 +++++++++++++++++++++++++++++++++++++++++++
configure.ac | 5 +++++
2 files changed, 48 insertions(+)
diff --git a/configure b/configure
index 7dec6b7bf9..b7420cceea 100755
--- a/configure
+++ b/configure
@@ -6303,6 +6303,49 @@ if test x"$pgac_cv_prog_CC_cflags__ftree_vectorize" =
x"yes"; then
fi
+ NOT_THE_CFLAGS=""
+ { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether ${CC} supports
-ftabstop=4, for NOT_THE_CFLAGS" >&5
+$as_echo_n "checking whether ${CC} supports -ftabstop=4, for NOT_THE_CFLAGS...
" >&6; }
+if ${pgac_cv_prog_CC_cflags__ftabstop_4+:} false; then :
+ $as_echo_n "(cached) " >&6
+else
+ pgac_save_CFLAGS=$CFLAGS
+pgac_save_CC=$CC
+CC=${CC}
+CFLAGS="${NOT_THE_CFLAGS} -ftabstop=4"
+ac_save_c_werror_flag=$ac_c_werror_flag
+ac_c_werror_flag=yes
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h. */
+
+int
+main ()
+{
+
+ ;
+ return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+ pgac_cv_prog_CC_cflags__ftabstop_4=yes
+else
+ pgac_cv_prog_CC_cflags__ftabstop_4=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+ac_c_werror_flag=$ac_save_c_werror_flag
+CFLAGS="$pgac_save_CFLAGS"
+CC="$pgac_save_CC"
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result:
$pgac_cv_prog_CC_cflags__ftabstop_4" >&5
+$as_echo "$pgac_cv_prog_CC_cflags__ftabstop_4" >&6; }
+if test x"$pgac_cv_prog_CC_cflags__ftabstop_4" = x"yes"; then
+ NOT_THE_CFLAGS="${NOT_THE_CFLAGS} -ftabstop=4"
+fi
+
+
+ if test -n "$NOT_THE_CFLAGS"; then
+ CPPFLAGS="$CPPFLAGS -ftabstop=4"
+ fi
#
# The following tests want to suppress various unhelpful warnings by adding
# -Wno-foo switches. But gcc won't complain about unrecognized -Wno-foo
diff --git a/configure.ac b/configure.ac
index d093fb88dd..b1d7ac9fc2 100644
--- a/configure.ac
+++ b/configure.ac
@@ -525,6 +525,11 @@ if test "$GCC" = yes -a "$ICC" = no; then
PGAC_PROG_CC_VAR_OPT(CFLAGS_UNROLL_LOOPS, [-funroll-loops])
# Optimization flags for specific files that benefit from vectorization
PGAC_PROG_CC_VAR_OPT(CFLAGS_VECTORIZE, [-ftree-vectorize])
+ NOT_THE_CFLAGS=""
+ PGAC_PROG_CC_VAR_OPT(NOT_THE_CFLAGS, [-ftabstop=4])
+ if test -n "$NOT_THE_CFLAGS"; then
+ CPPFLAGS="$CPPFLAGS -ftabstop=4"
+ fi
#
# The following tests want to suppress various unhelpful warnings by adding
# -Wno-foo switches. But gcc won't complain about unrecognized -Wno-foo
--
2.36.1
