In standard C '{ 0 }' is valid to initialize any compound object.
OTOH, Sparse allows '{ }' for the same purpose but:
1) '{ }' is not standard
2) Sparse warns when using '0' to initialize pointers.
Some projects (git) legitimately like to be able to use the
standard '{ 0 }' without the null-pointer warnings
So, add a new warning flag (-Wno-universal-initializer) to
handle '{ 0 }' as '{ }', suppressing the warnings.
Reference: https://lore.kernel.org/git/1df91aa4-dda5-64da-6ae3-5d65e50a55c5@xxxxxxxxxxxxxxxxxxxx/
Reference: https://lore.kernel.org/git/e6796c60-a870-e761-3b07-b680f934c537@xxxxxxxxxxxxxxxxxxxx/
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>
---
Suggestions for a better name than this -W[no-]universal-initializer
are warmly welcome.
-- Luc
lib.c | 2 ++
lib.h | 1 +
parse.c | 7 +++++++
sparse.1 | 8 ++++++++
token.h | 7 +++++++
validation/Wuniv-init-ko.c | 14 ++++++++++++++
validation/Wuniv-init-ok.c | 11 +++++++++++
7 files changed, 50 insertions(+)
create mode 100644 validation/Wuniv-init-ko.c
create mode 100644 validation/Wuniv-init-ok.c
diff --git a/lib.c b/lib.c
index f9ec285e8fea..9ee8d3cf6b21 100644
--- a/lib.c
+++ b/lib.c
@@ -295,6 +295,7 @@ int Wtransparent_union = 0;
int Wtypesign = 0;
int Wundef = 0;
int Wuninitialized = 1;
+int Wuniversal_initializer = 1;
int Wunknown_attribute = 0;
int Wvla = 1;
@@ -782,6 +783,7 @@ static const struct flag warnings[] = {
{ "typesign", &Wtypesign },
{ "undef", &Wundef },
{ "uninitialized", &Wuninitialized },
+ { "universal-initializer", &Wuniversal_initializer },
{ "unknown-attribute", &Wunknown_attribute },
{ "vla", &Wvla },
};
diff --git a/lib.h b/lib.h
index b18295a889cb..5e6db111170a 100644
--- a/lib.h
+++ b/lib.h
@@ -184,6 +184,7 @@ extern int Wtransparent_union;
extern int Wtypesign;
extern int Wundef;
extern int Wuninitialized;
+extern int Wuniversal_initializer;
extern int Wunknown_attribute;
extern int Wvla;
diff --git a/parse.c b/parse.c
index a29c67c8cf41..48494afc6f2c 100644
--- a/parse.c
+++ b/parse.c
@@ -2750,6 +2750,13 @@ static struct token *initializer_list(struct expression_list **list, struct toke
{
struct expression *expr;
+ // '{ 0 }' is equivalent to '{ }' unless wanting all possible
+ // warnings about using '0' to initialize a null-pointer.
+ if (!Wuniversal_initializer) {
+ if (match_token_zero(token) && match_op(token->next, '}'))
+ token = token->next;
+ }
+
for (;;) {
token = single_initializer(&expr, token);
if (!expr)
diff --git a/sparse.1 b/sparse.1
index 574caef3acbb..50e928392573 100644
--- a/sparse.1
+++ b/sparse.1
@@ -428,6 +428,14 @@ However, this behavior can lead to subtle errors.
Sparse does not issue these warnings by default.
.
+.TP
+.B \-Wuniversal\-initializer
+Do not suppress warnings about 0 used to initialize a null-pointer
+when using '{ 0 }' as initializer.
+
+Sparse issues these warnings by default. To turn them off, use
+\fB\-Wno\-universal\-initializer\fR.
+.
.SH MISC OPTIONS
.TP
.B \-\-arch=\fIARCH\fR
diff --git a/token.h b/token.h
index 292db167e4a8..33a6eda1cc53 100644
--- a/token.h
+++ b/token.h
@@ -241,4 +241,11 @@ static inline int match_ident(struct token *token, struct ident *id)
return token->pos.type == TOKEN_IDENT && token->ident == id;
}
+static inline int match_token_zero(struct token *token)
+{
+ if (token_type(token) != TOKEN_NUMBER)
+ return false;
+ return token->number[0] == '0' && !token->number[1];
+}
+
#endif
diff --git a/validation/Wuniv-init-ko.c b/validation/Wuniv-init-ko.c
new file mode 100644
index 000000000000..315c211a5db6
--- /dev/null
+++ b/validation/Wuniv-init-ko.c
@@ -0,0 +1,14 @@
+struct s {
+ void *ptr;
+};
+
+
+static struct s s = { 0 };
+
+/*
+ * check-name: univ-init-ko
+ *
+ * check-error-start
+Wuniv-init-ko.c:6:23: warning: Using plain integer as NULL pointer
+ * check-error-end
+ */
diff --git a/validation/Wuniv-init-ok.c b/validation/Wuniv-init-ok.c
new file mode 100644
index 000000000000..c39647517323
--- /dev/null
+++ b/validation/Wuniv-init-ok.c
@@ -0,0 +1,11 @@
+struct s {
+ void *ptr;
+};
+
+
+static struct s s = { 0 };
+
+/*
+ * check-name: univ-init-ok
+ * check-command: sparse -Wno-universal-initializer $file
+ */
--
2.26.2
