Module Name: src
Committed By: rillig
Date: Sun Jan 16 10:11:38 UTC 2022
Modified Files:
src/tests/usr.bin/xlint/lint1: msg_193.c msg_193.exp
Log Message:
tests/lint: document why accidental double semicolons are hard to detect
To generate a diff of this commit:
cvs rdiff -u -r1.16 -r1.17 src/tests/usr.bin/xlint/lint1/msg_193.c
cvs rdiff -u -r1.15 -r1.16 src/tests/usr.bin/xlint/lint1/msg_193.exp
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/tests/usr.bin/xlint/lint1/msg_193.c
diff -u src/tests/usr.bin/xlint/lint1/msg_193.c:1.16 src/tests/usr.bin/xlint/lint1/msg_193.c:1.17
--- src/tests/usr.bin/xlint/lint1/msg_193.c:1.16 Sat Jan 15 23:21:34 2022
+++ src/tests/usr.bin/xlint/lint1/msg_193.c Sun Jan 16 10:11:38 2022
@@ -1,4 +1,4 @@
-/* $NetBSD: msg_193.c,v 1.16 2022/01/15 23:21:34 rillig Exp $ */
+/* $NetBSD: msg_193.c,v 1.17 2022/01/16 10:11:38 rillig Exp $ */
# 3 "msg_193.c"
// Test for message: statement not reached [193]
@@ -672,6 +672,27 @@ test_null_statement(void)
;;
/*
+ * If assertions are disabled with -DNDEBUG and __lint__ is defined,
+ * NetBSD's <assert.h> defines assert(x) to nothing, leaving only
+ * the trailing semicolon. If there are several assertions next to
+ * each other, without any whitespace in between (very unusual), the
+ * GCC preprocessor generates ";;" for them, which makes them
+ * indistinguishable from the literal ";;" from the typo above.
+ *
+ * (echo '#include <assert.h>'; echo 'assert(0);assert(1);') \
+ * | gcc -DNDEBUG -E - -D__lint__
+ *
+ * To actually see the difference, lint would need to look at the
+ * code before preprocessing and compare it with the preprocessed
+ * code, which would be a lot of work.
+ *
+ * Apart from the above edge case, detecting extra semicolons would
+ * be possible, but lint would have to look at the whitespace between
+ * the tokens, and this is something that it doesn't do at all, as of
+ * 2022-01-16.
+ */
+
+ /*
* A stand-alone null statement, on the other hand, has its purpose.
* Without it, the 'for' loop would not be complete. The NetBSD
* style is to use 'continue;' instead of a simple ';'.
Index: src/tests/usr.bin/xlint/lint1/msg_193.exp
diff -u src/tests/usr.bin/xlint/lint1/msg_193.exp:1.15 src/tests/usr.bin/xlint/lint1/msg_193.exp:1.16
--- src/tests/usr.bin/xlint/lint1/msg_193.exp:1.15 Sat Jan 15 23:21:34 2022
+++ src/tests/usr.bin/xlint/lint1/msg_193.exp Sun Jan 16 10:11:38 2022
@@ -87,4 +87,4 @@ msg_193.c(597): warning: statement not r
msg_193.c(606): warning: statement not reached [193]
msg_193.c(627): warning: statement not reached [193]
msg_193.c(655): warning: statement not reached [193]
-msg_193.c(683): warning: statement not reached [193]
+msg_193.c(704): warning: statement not reached [193]
