When the argument to a directive with a length modifier like %lu
in a call to a GCC diagnostic function such as warning()) is not
of the right integer type, GCC suggests to replace the length
modifier in the directive with 'w'. For instance:
warning: format ‘%lu’ expects argument of type ‘long unsigned int’,
but argument 2 has type ‘int’ [-Wformat=]
f ("%lu", 0);
~~^
%wu
To issue the right hint (i.e., %u in the message above) the attached
patch introduces a new format_lengths enumerator to represent the 'w'
modifier.
Tested on x86_64-linux.
Martin
PR c/80619 - bad fix-it hint for GCC %lu directive with int argument: %wu
gcc/c-family/ChangeLog:
PR c/80619
* c-format.c (printf_length_specs): Set FMT_LEN_w for "w".
(asm_fprintf_length_spec): Same.
* c-format.h (format_lengths): Add FMT_LEN_w.
gcc/testsuite/ChangeLog:
PR c/80619
* gcc.dg/format/pr80619.c: New test.
diff --git a/gcc/c-family/c-format.c b/gcc/c-family/c-format.c
index 6363fa4f686..1fa551957d9 100644
--- a/gcc/c-family/c-format.c
+++ b/gcc/c-family/c-format.c
@@ -497,7 +497,7 @@ static const format_length_info printf_length_specs[] =
static const format_length_info asm_fprintf_length_specs[] =
{
{ "l", FMT_LEN_l, STD_C89, "ll", FMT_LEN_ll, STD_C89, 0 },
- { "w", FMT_LEN_none, STD_C89, NO_FMT, 0 },
+ { "w", FMT_LEN_w, STD_C89, NO_FMT, 0 },
{ NO_FMT, NO_FMT, 0 }
};
@@ -505,7 +505,7 @@ static const format_length_info asm_fprintf_length_specs[] =
static const format_length_info gcc_diag_length_specs[] =
{
{ "l", FMT_LEN_l, STD_C89, "ll", FMT_LEN_ll, STD_C89, 0 },
- { "w", FMT_LEN_none, STD_C89, NO_FMT, 0 },
+ { "w", FMT_LEN_w, STD_C89, NO_FMT, 0 },
{ NO_FMT, NO_FMT, 0 }
};
diff --git a/gcc/c-family/c-format.h b/gcc/c-family/c-format.h
index 972ba46f109..6aa68dfe883 100644
--- a/gcc/c-family/c-format.h
+++ b/gcc/c-family/c-format.h
@@ -36,6 +36,7 @@ enum format_lengths
FMT_LEN_H,
FMT_LEN_D,
FMT_LEN_DD,
+ FMT_LEN_w, /* GCC's HOST_WIDE_INT. */
FMT_LEN_MAX
};
diff --git a/gcc/testsuite/gcc.dg/format/pr80619.c b/gcc/testsuite/gcc.dg/format/pr80619.c
new file mode 100644
index 00000000000..c9f0496a1c2
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/format/pr80619.c
@@ -0,0 +1,89 @@
+/* PR c/80619 - bad fix-it hint for GCC %lu directive with int argument: %wu
+ { dg-do compile }
+ { dg-options "-Wall -fdiagnostics-show-caret" } */
+
+void T (const char*, ...) __attribute__ ((format (__gcc_diag__, 1, 2)));
+
+void test_suggested_modifier (void)
+{
+ T ("%ld", 0); // { dg-warning "format '%ld' expects argument of type 'long int', but argument 2 has type 'int'" }
+ /* { dg-begin-multiline-output "" }
+ T ("%ld", 0);
+ ~~^ ~
+ | |
+ | int
+ long int
+ %d
+ { dg-end-multiline-output "" } */
+
+ T ("%li", 0); // { dg-warning "format '%li' expects argument of type 'long int', but argument 2 has type 'int'" }
+ /* { dg-begin-multiline-output "" }
+ T ("%li", 0);
+ ~~^ ~
+ | |
+ | int
+ long int
+ %i
+ { dg-end-multiline-output "" } */
+
+ T ("%lu", 0); // { dg-warning "format '%lu' expects argument of type 'long unsigned int', but argument 2 has type 'int'" }
+ /* { dg-begin-multiline-output "" }
+ T ("%lu", 0);
+ ~~^ ~
+ | |
+ | int
+ long unsigned int
+ %u
+ { dg-end-multiline-output "" } */
+
+ T ("%lx", 0); // { dg-warning "format '%lx' expects argument of type 'long unsigned int', but argument 2 has type 'int'" }
+ /* { dg-begin-multiline-output "" }
+ T ("%lx", 0);
+ ~~^ ~
+ | |
+ | int
+ long unsigned int
+ %x
+ { dg-end-multiline-output "" } */
+
+ T ("%lli", 0); // { dg-warning "format '%lli' expects argument of type 'long long int', but argument 2 has type 'int'" }
+ /* { dg-begin-multiline-output "" }
+ T ("%lli", 0);
+ ~~~^ ~
+ | |
+ | int
+ long long int
+ %i
+ { dg-end-multiline-output "" } */
+
+ T ("%llo", 0); // { dg-warning "format '%llo' expects argument of type 'long long unsigned int', but argument 2 has type 'int'" }
+ /* { dg-begin-multiline-output "" }
+ T ("%llo", 0);
+ ~~~^ ~
+ | |
+ | int
+ long long unsigned int
+ %o
+ { dg-end-multiline-output "" } */
+
+ T ("%llu", 0); // { dg-warning "format '%llu' expects argument of type 'long long unsigned int', but argument 2 has type 'int'" }
+ /* { dg-begin-multiline-output "" }
+ T ("%llu", 0);
+ ~~~^ ~
+ | |
+ | int
+ long long unsigned int
+ %u
+ { dg-end-multiline-output "" } */
+
+ T ("%llx", 0); // { dg-warning "format '%llx' expects argument of type 'long long unsigned int', but argument 2 has type 'int'" }
+ /* { dg-begin-multiline-output "" }
+ T ("%llx", 0);
+ ~~~^ ~
+ | |
+ | int
+ long long unsigned int
+ %x
+ { dg-end-multiline-output "" } */
+}
+
