diff(1): don't reject specifying the same format multiple times

This may happen, for instance, if one happens to have an alias of diff to
diff -up and attempts to specify the amount of context on top of that.

Aliases like this may cause other problems, but if they're really not ever
generating non-unified diffs then we should at least not break that
use-case.

In addition, we'll now pick up a format mismatch if -p is specified with
!contextual && !unified && !unset.

Fix up a small trailing whitespace nit in the tests while we're here, and
add tests to make sure that we can double up all the formatting options.

Reported by:	jbeich
MFC after:	3 days

1 files changed, 8 insertions, 1 deletions

diff --git a/usr.bin/diff/tests/diff_test.sh b/usr.bin/diff/tests/diff_test.sh
index 8385a6224865..6f4b484b3a37 100755
--- a/usr.bin/diff/tests/diff_test.sh
+++ b/usr.bin/diff/tests/diff_test.sh
@@ -186,6 +186,13 @@ conflicting_format_body()
 	atf_check -s exit:2 -e ignore diff -q -c A B
 	atf_check -s exit:2 -e ignore diff --normal -c A B
 	atf_check -s exit:2 -e ignore diff -c --normal A B
+
+	atf_check -s exit:1 -o ignore -e ignore diff -u -u A B
+	atf_check -s exit:1 -o ignore -e ignore diff -e -e A B
+	atf_check -s exit:1 -o ignore -e ignore diff -y -y A B
+	atf_check -s exit:1 -o ignore -e ignore diff -q -q A B
+	atf_check -s exit:1 -o ignore -e ignore diff -c -c A B
+	atf_check -s exit:1 -o ignore -e ignore diff --normal --normal A B
 }
 
 atf_init_test_cases()
@@ -201,5 +208,5 @@ atf_init_test_cases()
 	atf_add_test_case b230049
 	atf_add_test_case Bflag
 	atf_add_test_case tabsize
-	atf_add_test_case conflicting_format 
+	atf_add_test_case conflicting_format
 }