On Tue, 2018-11-20 at 22:23 +0000, Joseph Myers wrote:
> On Tue, 20 Nov 2018, David Malcolm wrote:
>
> > Should I do:
>
> You should do whatever is appropriate for the warning in
> question. But if
> what's appropriate for the warning in question includes types that
> are
> compatible but not the same, the comments need to avoid saying it's
> about
> the types being the same.
Thanks.
Here's an updated version of the patch. I added a new
compatible_types_for_indirection_note_p
specifically for use by maybe_emit_indirection_note, and provided
implementations for C and C++.
Successfully bootstrapped & regrtested on x86_64-pc-linux-gnu.
OK for trunk?
Changed in v4: introduce a compatible_types_for_indirection_note_p
function, and use it in place of same_type_p.
Changed in v3: use same_type_p rather than pointer equality.
Provide implementation of same_type_p for C.
Changed in v2: add a note, and put the fix-it hint on that instead
Blurb follows:
This patch adds a note with a fix-it hint to various
pointer-vs-non-pointer diagnostics, suggesting the addition of
a leading '&' or '*'.
For example, note the ampersand fix-it hint in the following:
demo.c: In function 'int main()':
demo.c:5:22: error: invalid conversion from 'pthread_key_t' {aka 'unsigned int'}
to 'pthread_key_t*' {aka 'unsigned int*'} [-fpermissive]
5 | pthread_key_create(key, NULL);
| ^~~
| |
| pthread_key_t {aka unsigned int}
demo.c:5:22: note: possible fix: take the address with '&'
5 | pthread_key_create(key, NULL);
| ^~~
| &
In file included from demo.c:1:
/usr/include/pthread.h:1122:47: note: initializing argument 1 of
'int pthread_key_create(pthread_key_t*, void (*)(void*))'
1122 | extern int pthread_key_create (pthread_key_t *__key,
| ~~~~~~~~~~~~~~~^~~~~
gcc/c-family/ChangeLog:
PR c++/87850
* c-common.c: Include "gcc-rich-location.h".
(maybe_emit_indirection_note): New function.
* c-common.h (maybe_emit_indirection_note): New decl.
(compatible_types_for_indirection_note_p): New decl.
gcc/c/ChangeLog:
PR c++/87850
* c-typeck.c (compatible_types_for_indirection_note_p): New
function.
(convert_for_assignment): Call maybe_emit_indirection_note for
pointer vs non-pointer diagnostics.
gcc/cp/ChangeLog:
PR c++/87850
* call.c (convert_like_real): Call
maybe_emit_indirection_note for "invalid conversion" diagnostic.
* typeck.c (compatible_types_for_indirection_note_p): New
function.
gcc/testsuite/ChangeLog:
PR c++/87850
* c-c++-common/indirection-fixits.c: New test.
---
gcc/c-family/c-common.c | 35 +++
gcc/c-family/c-common.h | 4 +
gcc/c/c-typeck.c | 18 +-
gcc/cp/call.c | 2 +
gcc/cp/typeck.c | 8 +
gcc/testsuite/c-c++-common/indirection-fixits.c | 299 ++++++++++++++++++++++++
6 files changed, 364 insertions(+), 2 deletions(-)
create mode 100644 gcc/testsuite/c-c++-common/indirection-fixits.c
diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c
index 9d51815..f235c9d 100644
--- a/gcc/c-family/c-common.c
+++ b/gcc/c-family/c-common.c
@@ -48,6 +48,7 @@ along with GCC; see the file COPYING3. If not see
#include "gimplify.h"
#include "substring-locations.h"
#include "spellcheck.h"
+#include "gcc-rich-location.h"
#include "selftest.h"
cpp_reader *parse_in; /* Declared in c-pragma.h. */
@@ -8420,6 +8421,40 @@ maybe_suggest_missing_token_insertion (rich_location
*richloc,
}
}
+/* Potentially emit a note about likely missing '&' or '*',
+ depending on EXPR and EXPECTED_TYPE. */
+
+void
+maybe_emit_indirection_note (location_t loc,
+ tree expr, tree expected_type)
+{
+ gcc_assert (expr);
+ gcc_assert (expected_type);
+
+ tree actual_type = TREE_TYPE (expr);
+
+ /* Missing '&'. */
+ if (TREE_CODE (expected_type) == POINTER_TYPE
+ && compatible_types_for_indirection_note_p (actual_type,
+ TREE_TYPE (expected_type))
+ && lvalue_p (expr))
+ {
+ gcc_rich_location richloc (loc);
+ richloc.add_fixit_insert_before ("&");
+ inform (&richloc, "possible fix: take the address with %qs", "&");
+ }
+
+ /* Missing '*'. */
+ if (TREE_CODE (actual_type) == POINTER_TYPE
+ && compatible_types_for_indirection_note_p (TREE_TYPE (actual_type),
+ expected_type))
+ {
+ gcc_rich_location richloc (loc);
+ richloc.add_fixit_insert_before ("*");
+ inform (&richloc, "possible fix: dereference with %qs", "*");
+ }
+}
+
#if CHECKING_P
namespace selftest {
diff --git a/gcc/c-family/c-common.h b/gcc/c-family/c-common.h
index 4187343..0b1fdd7 100644
--- a/gcc/c-family/c-common.h
+++ b/gcc/c-family/c-common.h
@@ -1355,6 +1355,10 @@ extern void maybe_add_include_fixit (rich_location *,
const char *, bool);
extern void maybe_suggest_missing_token_insertion (rich_location *richloc,
enum cpp_ttype token_type,
location_t prev_token_loc);
+extern void maybe_emit_indirection_note (location_t loc,
+ tree expr, tree expected_type);
+extern bool compatible_types_for_indirection_note_p (tree type1, tree type2);
+
extern tree braced_list_to_string (tree, tree);
extern bool has_attribute (location_t, tree, tree, tree (*)(tree));
diff --git a/gcc/c/c-typeck.c b/gcc/c/c-typeck.c
index 81c520a..cb7184b 100644
--- a/gcc/c/c-typeck.c
+++ b/gcc/c/c-typeck.c
@@ -1004,6 +1004,14 @@ common_type (tree t1, tree t2)
return c_common_type (t1, t2);
}
+/* C implementation of compatible_types_for_indirection_note_p. */
+
+bool
+compatible_types_for_indirection_note_p (tree type1, tree type2)
+{
+ return comptypes (type1, type2) == 1;
+}
+
/* Return 1 if TYPE1 and TYPE2 are compatible types for assignment
or various other operations. Return 2 if they are compatible
but a warning may be needed if you use them together. */
@@ -7293,7 +7301,10 @@ convert_for_assignment (location_t location, location_t
expr_loc, tree type,
if (pedwarn (&richloc, OPT_Wint_conversion,
"passing argument %d of %qE makes pointer from "
"integer without a cast", parmnum, rname))
- inform_for_arg (fundecl, expr_loc, parmnum, type, rhstype);
+ {
+ maybe_emit_indirection_note (expr_loc, rhs, type);
+ inform_for_arg (fundecl, expr_loc, parmnum, type, rhstype);
+ }
}
break;
case ic_assign:
@@ -7329,7 +7340,10 @@ convert_for_assignment (location_t location, location_t
expr_loc, tree type,
if (pedwarn (&richloc, OPT_Wint_conversion,
"passing argument %d of %qE makes integer from "
"pointer without a cast", parmnum, rname))
- inform_for_arg (fundecl, expr_loc, parmnum, type, rhstype);
+ {
+ maybe_emit_indirection_note (expr_loc, rhs, type);
+ inform_for_arg (fundecl, expr_loc, parmnum, type, rhstype);
+ }
}
break;
case ic_assign:
diff --git a/gcc/cp/call.c b/gcc/cp/call.c
index ee099cc..a25d109 100644
--- a/gcc/cp/call.c
+++ b/gcc/cp/call.c
@@ -6862,6 +6862,8 @@ convert_like_real (conversion *convs, tree expr, tree fn,
int argnum,
complained = permerror (&richloc,
"invalid conversion from %qH to %qI",
TREE_TYPE (expr), totype);
+ if (complained)
+ maybe_emit_indirection_note (loc, expr, totype);
}
if (complained && fn)
inform (get_fndecl_argument_location (fn, argnum),
diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c
index 81cb405..2730f77 100644
--- a/gcc/cp/typeck.c
+++ b/gcc/cp/typeck.c
@@ -1448,6 +1448,14 @@ structural_comptypes (tree t1, tree t2, int strict)
return comp_type_attributes (t1, t2);
}
+/* C++ implementation of compatible_types_for_indirection_note_p. */
+
+bool
+compatible_types_for_indirection_note_p (tree type1, tree type2)
+{
+ return same_type_p (type1, type2);
+}
+
/* Return true if T1 and T2 are related as allowed by STRICT. STRICT
is a bitwise-or of the COMPARE_* flags. */
diff --git a/gcc/testsuite/c-c++-common/indirection-fixits.c
b/gcc/testsuite/c-c++-common/indirection-fixits.c
new file mode 100644
index 0000000..8987ee9
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/indirection-fixits.c
@@ -0,0 +1,299 @@
+/* { dg-options "-fdiagnostics-show-caret" } */
+
+void takes_int_ptr(int*);
+void takes_char_ptr(char*);
+void takes_int(int);
+int returns_int(void);
+
+int ivar;
+char cvar;
+int *int_ptr;
+char *char_ptr;
+
+void test_1 (void)
+{
+ takes_int_ptr(&ivar);
+ takes_int_ptr(int_ptr);
+ takes_char_ptr(&cvar);
+ takes_char_ptr(char_ptr);
+
+ ivar = 42;
+ cvar = 'b';
+ int_ptr = &ivar;
+ char_ptr = &cvar;
+}
+
+void test_2 (void)
+{
+ takes_int_ptr(ivar); /* { dg-warning "" "" { target c } } */
+ /* { dg-error "" "" { target c++ } .-1 } */
+ /* { dg-message "possible fix: take the address with '&'" "" { target *-*-*
} .-2 } */
+
+ /* Expect an '&' fix-it hint. */
+ /* { dg-begin-multiline-output "" }
+ takes_int_ptr(ivar);
+ ^~~~
+ |
+ int
+ { dg-end-multiline-output "" } */
+ /* { dg-begin-multiline-output "" }
+ takes_int_ptr(ivar);
+ ^~~~
+ &
+ { dg-end-multiline-output "" } */
+ /* { dg-begin-multiline-output "" }
+ void takes_int_ptr(int*);
+ ^~~~
+ { dg-end-multiline-output "" } */
+}
+
+void test_3 (void)
+{
+ takes_int_ptr(cvar); /* { dg-warning "" "" { target c } } */
+ /* { dg-error "" "" { target c++ } .-1 } */
+
+ /* Don't expect an '&' fix-it hint. */
+ /* { dg-begin-multiline-output "" }
+ takes_int_ptr(cvar);
+ ^~~~
+ |
+ char
+ { dg-end-multiline-output "" } */
+ /* { dg-begin-multiline-output "" }
+ void takes_int_ptr(int*);
+ ^~~~
+ { dg-end-multiline-output "" } */
+}
+
+void test_4 (void)
+{
+ takes_char_ptr(ivar); /* { dg-warning "" "" { target c } } */
+ /* { dg-error "" "" { target c++ } .-1 } */
+
+ /* Don't expect an '&' fix-it hint. */
+ /* { dg-begin-multiline-output "" }
+ takes_char_ptr(ivar);
+ ^~~~
+ |
+ int
+ { dg-end-multiline-output "" } */
+ /* { dg-begin-multiline-output "" }
+ void takes_char_ptr(char*);
+ ^~~~~
+ { dg-end-multiline-output "" } */
+}
+
+void test_5 (void)
+{
+ takes_char_ptr(cvar); /* { dg-warning "" "" { target c } } */
+ /* { dg-error "" "" { target c++ } .-1 } */
+
+ /* Expect an '&' fix-it hint. */
+ /* { dg-begin-multiline-output "" }
+ takes_char_ptr(cvar);
+ ^~~~
+ |
+ char
+ { dg-end-multiline-output "" } */
+ /* { dg-begin-multiline-output "" }
+ takes_char_ptr(cvar);
+ ^~~~
+ &
+ { dg-end-multiline-output "" } */
+ /* { dg-begin-multiline-output "" }
+ void takes_char_ptr(char*);
+ ^~~~~
+ { dg-end-multiline-output "" } */
+}
+
+void test_6 (void)
+{
+ takes_int(int_ptr); /* { dg-warning "" "" { target c } } */
+ /* { dg-error "" "" { target c++ } .-1 } */
+ /* { dg-message "possible fix: dereference with '*'" "" { target *-*-* } .-2
} */
+
+ /* Expect a '*' fix-it hint. */
+ /* { dg-begin-multiline-output "" }
+ takes_int(int_ptr);
+ ^~~~~~~
+ |
+ int *
+ { dg-end-multiline-output "" { target c } } */
+ /* { dg-begin-multiline-output "" }
+ takes_int(int_ptr);
+ ^~~~~~~
+ |
+ int*
+ { dg-end-multiline-output "" { target c++ } } */
+ /* { dg-begin-multiline-output "" }
+ takes_int(int_ptr);
+ ^~~~~~~
+ *
+ { dg-end-multiline-output "" } */
+ /* { dg-begin-multiline-output "" }
+ void takes_int(int);
+ ^~~
+ { dg-end-multiline-output "" } */
+}
+
+void test_7 (void)
+{
+ takes_int(char_ptr); /* { dg-warning "" "" { target c } } */
+ /* { dg-error "" "" { target c++ } .-1 } */
+
+ /* Don't expect a '*' fix-it hint. */
+ /* { dg-begin-multiline-output "" }
+ takes_int(char_ptr);
+ ^~~~~~~~
+ |
+ char *
+ { dg-end-multiline-output "" { target c } } */
+ /* { dg-begin-multiline-output "" }
+ takes_int(char_ptr);
+ ^~~~~~~~
+ |
+ char*
+ { dg-end-multiline-output "" { target c++ } } */
+ /* { dg-begin-multiline-output "" }
+ void takes_int(int);
+ ^~~
+ { dg-end-multiline-output "" } */
+}
+
+void test_8 (void)
+{
+ ivar = int_ptr; /* { dg-warning "" "" { target c } } */
+ /* { dg-error "" "" { target c++ } .-1 } */
+
+ /* Expect a fix-it hint from the C++ FE, but not from C (due to missing
+ location). */
+ /* { dg-begin-multiline-output "" }
+ ivar = int_ptr;
+ ^~~~~~~
+ |
+ int*
+ { dg-end-multiline-output "" { target c++ } } */
+ /* { dg-begin-multiline-output "" }
+ ivar = int_ptr;
+ ^~~~~~~
+ *
+ { dg-end-multiline-output "" { target c++ } } */
+ /* { dg-begin-multiline-output "" }
+ ivar = int_ptr;
+ ^
+ { dg-end-multiline-output "" { target c } } */
+}
+
+void test_9 (void)
+{
+ cvar = int_ptr; /* { dg-warning "" "" { target c } } */
+ /* { dg-error "" "" { target c++ } .-1 } */
+
+ /* Don't expect a '*' fix-it hint. */
+ /* { dg-begin-multiline-output "" }
+ cvar = int_ptr;
+ ^~~~~~~
+ |
+ int*
+ { dg-end-multiline-output "" { target c++ } } */
+ /* { dg-begin-multiline-output "" }
+ cvar = int_ptr;
+ ^
+ { dg-end-multiline-output "" { target c } } */
+}
+
+void test_10 (void)
+{
+ int_ptr = ivar; /* { dg-warning "" "" { target c } } */
+ /* { dg-error "" "" { target c++ } .-1 } */
+
+ /* Expect a fix-it hint from the C++ FE, but not from C (due to missing
+ location). */
+ /* { dg-begin-multiline-output "" }
+ int_ptr = ivar;
+ ^~~~
+ |
+ int
+ { dg-end-multiline-output "" { target c++ } } */
+ /* { dg-begin-multiline-output "" }
+ int_ptr = ivar;
+ ^~~~
+ &
+ { dg-end-multiline-output "" { target c++ } } */
+ /* { dg-begin-multiline-output "" }
+ int_ptr = ivar;
+ ^
+ { dg-end-multiline-output "" { target c } } */
+}
+
+void test_11 (void)
+{
+ char_ptr = ivar; /* { dg-warning "" "" { target c } } */
+ /* { dg-error "" "" { target c++ } .-1 } */
+
+ /* Don't expect a fix-it hint, due to mismatching types. */
+ /* { dg-begin-multiline-output "" }
+ char_ptr = ivar;
+ ^~~~
+ |
+ int
+ { dg-end-multiline-output "" { target c++ } } */
+ /* { dg-begin-multiline-output "" }
+ char_ptr = ivar;
+ ^
+ { dg-end-multiline-output "" { target c } } */
+}
+
+/* We shouldn't offer '&' fix-it hints for non-lvalues. */
+
+void test_12 (void)
+{
+ takes_int_ptr (returns_int ()); /* { dg-warning "" "" { target c } } */
+ /* { dg-error "" "" { target c++ } .-1 } */
+
+ /* { dg-begin-multiline-output "" }
+ takes_int_ptr (returns_int ());
+ ^~~~~~~~~~~~~~
+ |
+ int
+ { dg-end-multiline-output "" { target c } } */
+ /* { dg-begin-multiline-output "" }
+ takes_int_ptr (returns_int ());
+ ~~~~~~~~~~~~^~
+ |
+ int
+ { dg-end-multiline-output "" { target c++ } } */
+ /* { dg-begin-multiline-output "" }
+ void takes_int_ptr(int*);
+ ^~~~
+ { dg-end-multiline-output "" } */
+}
+
+/* Ignore typedefs when offering fix-it hints. */
+
+typedef int typedef_int_t;
+typedef_int_t typedef_int_t_var;
+
+void test_13 (void)
+{
+ takes_int_ptr (typedef_int_t_var); /* { dg-warning "" "" { target c } } */
+ /* { dg-error "" "" { target c++ } .-1 } */
+ /* { dg-message "possible fix: take the address with '&'" "" { target *-*-*
} .-2 } */
+
+ /* Expect an '&' fix-it hint. */
+ /* { dg-begin-multiline-output "" }
+ takes_int_ptr (typedef_int_t_var);
+ ^~~~~~~~~~~~~~~~~
+ |
+ typedef_int_t {aka int}
+ { dg-end-multiline-output "" } */
+ /* { dg-begin-multiline-output "" }
+ takes_int_ptr (typedef_int_t_var);
+ ^~~~~~~~~~~~~~~~~
+ &
+ { dg-end-multiline-output "" } */
+ /* { dg-begin-multiline-output "" }
+ void takes_int_ptr(int*);
+ ^~~~
+ { dg-end-multiline-output "" } */
+}
--
1.8.5.3
