On Tue, 2018-11-13 at 16:34 -0500, Jason Merrill wrote:
> On Mon, Nov 12, 2018 at 4:32 PM Martin Sebor <[email protected]>
> wrote:
> > On 11/11/2018 02:02 PM, David Malcolm wrote:
> > > On Sun, 2018-11-11 at 11:01 -0700, Martin Sebor wrote:
> > > > On 11/10/2018 12:01 AM, Eric Gallager wrote:
> > > > > On 11/9/18, David Malcolm <[email protected]> wrote:
> > > > > > This patch adds 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: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}
> > > > > > | &
> > > > >
> > > > > Having both the type and the fixit underneath the caret looks
> > > > > kind
> > > > > of confusing
> > > >
> > > > I agree it's rather subtle. Keeping the diagnostics separate
> > > > from
> > > > the suggested fix should avoid the confusion.
> > >
> > > FWIW, the fix-it hint is in a different color (assuming that gcc
> > > is
> > > invoked in an environment that prints that...)
> >
> > I figured it would be, but I'm still not sure it's good design
> > to be relying on color alone to distinguish between the problem
> > and the suggested fix. Especially when they are so close to one
> > another and the fix is just a single character with no obvious
> > relationship to the rest of the text on the screen. In other
> > warnings there's at least the "did you forget the '@'?" part
> > to give a clue, even though even there the connection between
> > the "did you forget" and the & several lines down wouldn't
> > necessarily be immediately apparent.
>
> Agreed, something along those lines would help to understand why the
> compiler is throwing a random & into the diagnostic.
>
> Jason
Here's an updated version which adds a note, putting the fix-it hint
on that instead (I attempted adding the text to the initial error,
but there was something of a combinatorial explosion of messages).
The above example becomes:
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,
| ~~~~~~~~~~~~~~~^~~~~
Successfully bootstrapped & regrtested on x86_64-pc-linux-gnu.
OK for trunk?
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.
gcc/c/ChangeLog:
PR c++/87850
* c-typeck.c (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.
gcc/testsuite/ChangeLog:
PR c++/87850
* c-c++-common/indirection-fixits.c: New test.
---
gcc/c-family/c-common.c | 33 +++
gcc/c-family/c-common.h | 2 +
gcc/c/c-typeck.c | 10 +-
gcc/cp/call.c | 2 +
gcc/testsuite/c-c++-common/indirection-fixits.c | 270 ++++++++++++++++++++++++
5 files changed, 315 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 cd88f3a..d5c7c7f 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. */
@@ -8405,6 +8406,38 @@ 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
+ && 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
+ && 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 31cc273..e765d3c 100644
--- a/gcc/c-family/c-common.h
+++ b/gcc/c-family/c-common.h
@@ -1340,6 +1340,8 @@ 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 tree braced_list_to_string (tree, tree);
#if CHECKING_P
diff --git a/gcc/c/c-typeck.c b/gcc/c/c-typeck.c
index 5d4e973..efa836d 100644
--- a/gcc/c/c-typeck.c
+++ b/gcc/c/c-typeck.c
@@ -7061,7 +7061,10 @@ 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:
@@ -7097,7 +7100,10 @@ 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/testsuite/c-c++-common/indirection-fixits.c
b/gcc/testsuite/c-c++-common/indirection-fixits.c
new file mode 100644
index 0000000..4e45d66
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/indirection-fixits.c
@@ -0,0 +1,270 @@
+/* { 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 "" } */
+}
--
1.8.5.3
