[PATCH] Teach sparse about the __COUNTER__ predefined macro

[Luc Van Oostenryck <luc.vanoostenryck@gmail.com>]

On Fri, Jan 23, 2015 at 08:40:17AM -0800, Christopher Li wrote:
> On Thu, Jan 22, 2015 at 12:31 PM, Christian Borntraeger
> <borntraeger@de.ibm.com> wrote:
> > Linus, Christopher,
> >
> > Commit  0f25c6a78e08fdc15af5e599d836fa24349c042f ("Add warning about duplicate initializers") has a false positive on arch/s390/kvm/kvm-s390.c
> >
> >   CHECK   arch/s390/kvm/kvm-s390.c
> > arch/s390/kvm/kvm-s390.c:1823:1: error: symbol '__UNIQUE_ID_alias__COUNTER__' has multiple initializers (originally initialized at arch/s390/kvm/kvm-s390.c:1822)
> 
> Search the "__COUNTER__" macro shows that:
> https://gcc.gnu.org/onlinedocs/cpp/Common-Predefined-Macros.html
> 
> __COUNTER__This macro expands to sequential integral values starting
> from 0. In conjunction with the ## operator, this provides a
> convenient means to generate unique identifiers. Care must be taken to
> ensure that __COUNTER__ is not expanded prior to inclusion of
> precompiled headers which use it. Otherwise, the precompiled headers
> will not be used.
> 
> I think sparse haven't implement the __COUNTER__ macro. That is why it emit the
> error on duplicate entry.
> 
> Chris
> --


The following patch should fix that.


Luc


Subject: [PATCH] Teach sparse about the __COUNTER__ predefined macro.

Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
---
 ident-list.h                          |  1 +
 pre-process.c                         |  4 ++++
 validation/preprocessor/__COUNTER__.c | 12 ++++++++++++
 3 files changed, 17 insertions(+)
 create mode 100644 validation/preprocessor/__COUNTER__.c

diff --git a/ident-list.h b/ident-list.h
index d5a145f8..b65b667d 100644
--- a/ident-list.h
+++ b/ident-list.h
@@ -108,6 +108,7 @@ __IDENT(__TIME___ident, "__TIME__", 0);
 __IDENT(__func___ident, "__func__", 0);
 __IDENT(__FUNCTION___ident, "__FUNCTION__", 0);
 __IDENT(__PRETTY_FUNCTION___ident, "__PRETTY_FUNCTION__", 0);
+__IDENT(__COUNTER___ident, "__COUNTER__", 0);
 
 /* Sparse commands */
 IDENT_RESERVED(__context__);
diff --git a/pre-process.c b/pre-process.c
index 1aa3d2c4..316247ac 100644
--- a/pre-process.c
+++ b/pre-process.c
@@ -181,6 +181,10 @@ static int expand_one_symbol(struct token **list)
 			time(&t);
 		strftime(buffer, 9, "%T", localtime(&t));
 		replace_with_string(token, buffer);
+	} else if (token->ident == &__COUNTER___ident) {
+		static int counter;
+
+		replace_with_integer(token, counter++);
 	}
 	return 1;
 }
diff --git a/validation/preprocessor/__COUNTER__.c b/validation/preprocessor/__COUNTER__.c
new file mode 100644
index 00000000..98187ee6
--- /dev/null
+++ b/validation/preprocessor/__COUNTER__.c
@@ -0,0 +1,12 @@
+__COUNTER__
+__COUNTER__
+/*
+ * check-name: __COUNTER__ #1
+ * check-command: sparse -E $file
+ *
+ * check-output-start
+
+0
+1
+ * check-output-end
+ */