Skip to content

build: Fix warnings about control paths #5806

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
wants to merge 1 commit into
base: main
Choose a base branch
from
Open

build: Fix warnings about control paths #5806

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
2 changes: 2 additions & 0 deletions lib/arraystats/class.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,8 @@ int AS_option_to_algorithm(const struct Option *option)
return CLASS_DISCONT;

G_fatal_error(_("Unknown algorithm '%s'"), option->answer);

return 0;
}

double AS_class_apply_algorithm(int algo, const double data[], int nrec,
Expand Down
2 changes: 2 additions & 0 deletions lib/gis/parser_dependencies.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -124,6 +124,8 @@ static int is_flag(const void *p)
}

G_fatal_error(_("Internal error: option or flag not found"));

return -1;
Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I know this is under a G_fatal_error, so shouldn't be reached. But the 4 usages of this function in this file only check with if (is_flag(p)) {}, so a non-zero value, here -1, doesn't mean the same.

Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Code after G_fatal_error is never reached and thus unnecessary. (Competent static analysers recognises this too).

Copy link
Member Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I know this is under a G_fatal_error, so shouldn't be reached. But the 4 usages of this function in this file only check with if (is_flag(p)) {}, so a non-zero value, here -1, doesn't mean the same.

You're right. We could do if (is_flag(p) == 1), but again, we'll never reach return -1 anyway. It's just there to suppress the warning.

}

static int is_present(const void *p)
Expand Down
7 changes: 4 additions & 3 deletions ps/ps.map/scale.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -17,9 +17,9 @@
static double do_scale(char *);

#ifdef __GNUC_MINOR__
static int OOPS(void) __attribute__((__noreturn__));
static void OOPS(void) __attribute__((__noreturn__));
#else
static int OOPS();
static void OOPS();
#endif

double scale(char *text)
Expand Down Expand Up @@ -131,9 +131,10 @@ static double do_scale(char *text)
return METERS_TO_INCHES * distance(PS.w.east, PS.w.west) * u1 / u2;
}
OOPS();
return 0;
}

static int OOPS(void)
static void OOPS(void)
{
G_fatal_error(_("PSmap: do_scale(): shouldn't happen"));
}
2 changes: 1 addition & 1 deletion raster/r.li/r.li.daemon/avl.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -208,7 +208,6 @@ static avl_node *avl_individua(const avl_tree root, const generic_cell k,
switch (ris) {
case GC_EQUAL: {
return root;
break;
}
case GC_HIGHER: {
*father = root;
Expand All @@ -227,6 +226,7 @@ static avl_node *avl_individua(const avl_tree root, const generic_cell k,
G_fatal_error("\avl.c: avl_individua: error");
}
}
return NULL;
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

This is also never reached. I wonder how you triggered these warnings?

Copy link
Member Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I think MSVC reports these warnings by default:

C:\Users\hcho\usr\grass\grass\raster\r.li\r.li.daemon\avl.c(230,1): warning C4715: 'avl_individua': not all control paths return a value [C:\Users\hcho\usr\grass\grass\build27\raster\r.li\grass_rli.vcxproj]

Copy link
Member Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

https://learn.microsoft.com/en-us/cpp/error-messages/compiler-warnings/compiler-warning-level-1-c4715?view=msvc-170

Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

At the end of that page, it points ta a link that shows how to use __declspec(noreturn) to annotate a function that never returns, for that analysis.

https://learn.microsoft.com/en-us/cpp/cpp/noreturn?view=msvc-170

Copy link
Member Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

That's for void functions technically. Or

It does not make sense for a noreturn function to have a return type other than void.

https://gcc.gnu.org/onlinedocs/gcc-3.4.3/gcc/Function-Attributes.html

Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I meant fixing the annotation on G_fatal_error, it should be void right?

Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

G_fatal_error is attributed with __attribute__((noreturn)):

grass/include/grass/defs/gis.h

Lines 312 to 313 in d129608

void G_fatal_error(const char *, ...) __attribute__((format(printf, 1, 2)))
__attribute__((noreturn));

maybe that needs an update for windows?

This is a very common practice (no return after G_fatal_error) in GRASS code, so this should be solved in a more general way.

Something like:

void G_fatal_error(const char *, ...) __attribute__((format(printf, 1, 2))) 
#if defined(_MSC_VER)
__declspec(noreturn);
#else
 __attribute__((noreturn));
#endif

Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

If my proposed change works, I'd suggest defining a macro in gis.h:

#if defined(_MSC_VER)
#define G_NORETURN __declspec(noreturn)
#else
#define G_NORETURN __attribute__((noreturn))
#endif

which then can be added:

void G_fatal_error(const char *, ...) __attribute__((format(printf, 1, 2))) G_NORETURN;

Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Or using the C11 keyword _Noreturn 

#if  __STDC_VERSION__ < 202311L
#define G_NORETURN _Noreturn
#else
#define G_NORETURN [[noreturn]]
#endif

...

G_NORETURN void G_fatal_error(const char *, ...) __attribute__((format(printf, 1, 2)));

(untested)

Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

The _Noreturn suggestion above doesn't work well with C++, however this seems to work:

#if __STDC_VERSION__ < 202311L
#if defined(_MSC_VER)
#define G_NORETURN __declspec(noreturn)
#else
#define G_NORETURN __attribute__((noreturn))
#endif
#else
#define G_NORETURN [[noreturn]]
#endif

(The [[noreturn]] attribute is added to C23 as well as C++11).

}

static int avl_height(const avl_tree root)
Expand Down
Loading