This patch adds the -Wincompatible-pointer-types option for a warning
we already have, so it's possible to suppress this specific warning, or
use it with -Werror= and so on.
As a followup change, I'm considering printing the types of the pointers;
saying merely e.g. "assignment from incompatible pointer type" seems to be too
austere. (We say "expected T but argument is of type U" when passing
arguments.)
This is for C/ObjC only, since in C++, we'd issue "cannot convert" error.
Bootstrapped/regtested on x86_64-linux, ok for trunk?
2014-06-30 Marek Polacek <pola...@redhat.com>
PR c/58286
* doc/invoke.texi: Document -Wincompatible-pointer-types.
c-family/
* c.opt (Wincompatible-pointer-types): New option.
c/
* c-typeck.c (convert_for_assignment): Pass
OPT_Wincompatible_pointer_types instead of 0 to WARN_FOR_ASSIGNMENT.
testsuite/
* gcc.dg/Wincompatible-pointer-types.c: New test.
diff --git gcc/c-family/c.opt gcc/c-family/c.opt
index 1d02bae..6448b1b 100644
--- gcc/c-family/c.opt
+++ gcc/c-family/c.opt
@@ -443,6 +443,10 @@ Wignored-qualifiers
C C++ Var(warn_ignored_qualifiers) Warning EnabledBy(Wextra)
Warn whenever type qualifiers are ignored.
+Wincompatible-pointer-types
+C ObjC Var(warn_incompatible_pointer_types) Init(1) Warning
+Warn when there is a conversion between pointers that have incompatible types
+
Winit-self
C ObjC C++ ObjC++ Var(warn_init_self) Warning LangEnabledBy(C++ ObjC++,Wall)
Warn about variables which are initialized to themselves
diff --git gcc/c/c-typeck.c gcc/c/c-typeck.c
index b62e830..fff26a3 100644
--- gcc/c/c-typeck.c
+++ gcc/c/c-typeck.c
@@ -6189,7 +6189,8 @@ convert_for_assignment (location_t location, location_t
expr_loc, tree type,
else
/* Avoid warning about the volatile ObjC EH puts on decls. */
if (!objc_ok)
- WARN_FOR_ASSIGNMENT (location, expr_loc, 0,
+ WARN_FOR_ASSIGNMENT (location, expr_loc,
+ OPT_Wincompatible_pointer_types,
G_("passing argument %d of %qE from "
"incompatible pointer type"),
G_("assignment from incompatible pointer type"),
diff --git gcc/doc/invoke.texi gcc/doc/invoke.texi
index dbc1132..dfae4f0 100644
--- gcc/doc/invoke.texi
+++ gcc/doc/invoke.texi
@@ -251,7 +251,7 @@ Objective-C and Objective-C++ Dialects}.
-Wno-format-contains-nul -Wno-format-extra-args -Wformat-nonliteral @gol
-Wformat-security -Wformat-signedness -Wformat-y2k @gol
-Wframe-larger-than=@var{len} -Wno-free-nonheap-object -Wjump-misses-init @gol
--Wignored-qualifiers @gol
+-Wignored-qualifiers -Wincompatible-pointer-types @gol
-Wimplicit -Wimplicit-function-declaration -Wimplicit-int @gol
-Winit-self -Winline @gol
-Wno-int-to-pointer-cast -Wno-invalid-offsetof @gol
@@ -4199,14 +4199,19 @@ This option is only active when @option{-ftree-vrp} is
active
(default for @option{-O2} and above). It warns about subscripts to arrays
that are always out of bounds. This warning is enabled by @option{-Wall}.
-@item -Wno-discarded-qualifiers
+@item -Wno-discarded-qualifiers @r{(C and Objective-C only)}
@opindex Wno-discarded-qualifiers
@opindex Wdiscarded-qualifiers
Do not warn if type qualifiers on pointers are being discarded.
Typically, the compiler will warn if a @code{const char *} variable is
passed to a function that takes @code{char *} parameter. This option
-can be used to suppress such a warning. This warning is only supported
-for C.
+can be used to suppress such a warning.
+
+@item -Wno-incompatible-pointer-types @r{(C and Objective-C only)}
+@opindex Wno-incompatible-pointer-types
+@opindex Wincompatible-pointer-types
+Do not warn when there is a conversion between pointers that have incompatible
+types.
@item -Wno-div-by-zero
@opindex Wno-div-by-zero
diff --git gcc/testsuite/gcc.dg/Wincompatible-pointer-types.c
gcc/testsuite/gcc.dg/Wincompatible-pointer-types.c
index e69de29..e765b27 100644
--- gcc/testsuite/gcc.dg/Wincompatible-pointer-types.c
+++ gcc/testsuite/gcc.dg/Wincompatible-pointer-types.c
@@ -0,0 +1,21 @@
+/* PR c/58286 */
+/* { dg-do compile } */
+/* { dg-options "-Wno-incompatible-pointer-types" } */
+
+void
+fn2 (short *s, long *l)
+{
+}
+
+unsigned *
+fn1 (void)
+{
+ int (*fpi) (int);
+ int (*fpd) (double) = fpi;
+ fpi = fpd;
+ char *di;
+ float *dp = &di;
+ di = dp;
+ fn2 (dp, di);
+ return dp;
+}
Marek
