OK.
On Wed, Mar 28, 2018 at 4:44 PM, David Malcolm <dmalc...@redhat.com> wrote:
> As of r256448, the C++ frontend underlines many bad arguments in its
> diagnostics; those where perform_overload_resolution returns a
> non-NULL candidate, but there's a failure in convert_like_real.
>
> However, for the case where perform_overload_resolution fails, but
> there's a single non-viable candidate, the error is diagnosed by
> cp_build_function_call_vec, and that currently doesn't underline
> the bad argument:
>
> $ cat test.cc
> void callee (int one, const char **two, int three);
>
> void
> caller (const char *fmt)
> {
> callee (1, fmt, 3);
> }
>
> We emit:
>
> $ g++ test.cc
> test.cc: In function 'void caller(const char*)':
> test.cc:6:20: error: cannot convert 'const char*' to 'const char**' for
> argument '2' to 'void callee(int, const char**, int)'
> callee (1, fmt, 3);
> ^
>
> It's going through convert_for_assignment, and
> implicitly using input_location.
>
> This patch updates convert_for_assignment for this case, using
> an EXPR_LOCATION if there is one, or falling back to input_location
> otherwise, underlining the argument in question:
>
> test.cc: In function 'void caller(const char*)':
> test.cc:6:14: error: cannot convert 'const char*' to 'const char**' for
> argument '2' to 'void callee(int, const char**, int)'
> callee (1, fmt, 3);
> ^~~
>
> Successfully bootstrapped & regrtested on x86_64-pc-linux-gnu; adds
> 117 PASS results to g++.sum.
>
> Not a regression as such, but I've been calling out the underlined
> arguments as a feature of gcc 8, so would be good to fix.
>
> OK for trunk?
>
> gcc/cp/ChangeLog:
> PR c++/85110
> * typeck.c (convert_for_assignment): When complaining due to
> conversions for an argument, attempt to use the location of the
> argument.
>
> gcc/testsuite/ChangeLog:
> PR c++/85110
> * g++.dg/diagnostic/param-type-mismatch-2.C: New test.
> ---
> gcc/cp/typeck.c | 5 +-
> .../g++.dg/diagnostic/param-type-mismatch-2.C | 175
> +++++++++++++++++++++
> 2 files changed, 178 insertions(+), 2 deletions(-)
> create mode 100644 gcc/testsuite/g++.dg/diagnostic/param-type-mismatch-2.C
>
> diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c
> index 0c2ebd1..e733c79 100644
> --- a/gcc/cp/typeck.c
> +++ b/gcc/cp/typeck.c
> @@ -8781,8 +8781,9 @@ convert_for_assignment (tree type, tree rhs,
> parmnum, complain, flags);
> }
> else if (fndecl)
> - error ("cannot convert %qH to %qI for argument %qP to %qD",
> - rhstype, type, parmnum, fndecl);
> + error_at (EXPR_LOC_OR_LOC (rhs, input_location),
> + "cannot convert %qH to %qI for argument %qP to %qD",
> + rhstype, type, parmnum, fndecl);
> else
> switch (errtype)
> {
> diff --git a/gcc/testsuite/g++.dg/diagnostic/param-type-mismatch-2.C
> b/gcc/testsuite/g++.dg/diagnostic/param-type-mismatch-2.C
> new file mode 100644
> index 0000000..ae84248
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/diagnostic/param-type-mismatch-2.C
> @@ -0,0 +1,175 @@
> +// { dg-options "-fdiagnostics-show-caret" }
> +
> +/* A collection of calls where argument 2 is of the wrong type. */
> +
> +/* decl, with argname. */
> +
> +extern int callee_1 (int one, const char **two, float three);
> +
> +int test_1 (int first, const char *second, float third)
> +{
> + return callee_1 (first, second, third); // { dg-error "27: cannot convert
> 'const char\\*' to 'const char\\*\\*' for argument '2' to 'int
> callee_1\\(int, const char\\*\\*, float\\)'" }
> + /* { dg-begin-multiline-output "" }
> + return callee_1 (first, second, third);
> + ^~~~~~
> + { dg-end-multiline-output "" } */
> +}
> +
> +/* decl, without argname. */
> +
> +extern int callee_2 (int, const char **, float);
> +
> +int test_2 (int first, const char *second, float third)
> +{
> + return callee_2 (first, second, third); // { dg-error "27: cannot convert
> 'const char\\*' to 'const char\\*\\*' for argument '2' to 'int
> callee_2\\(int, const char\\*\\*, float\\)'" }
> + /* { dg-begin-multiline-output "" }
> + return callee_2 (first, second, third);
> + ^~~~~~
> + { dg-end-multiline-output "" } */
> +}
> +
> +/* defn, with argname. */
> +
> +static int callee_3 (int one, const char **two, float three)
> +{
> + return callee_2 (one, two, three);
> +}
> +
> +int test_3 (int first, const char *second, float third)
> +{
> + return callee_3 (first, second, third); // { dg-error "27: cannot convert
> 'const char\\*' to 'const char\\*\\*' for argument '2' to 'int
> callee_3\\(int, const char\\*\\*, float\\)'" }
> + /* { dg-begin-multiline-output "" }
> + return callee_3 (first, second, third);
> + ^~~~~~
> + { dg-end-multiline-output "" } */
> +}
> +
> +/* static member, with argname. */
> +
> +struct s4 { static int member_1 (int one, const char **two, float three); };
> // { dg-line s4_member_1 }
> +
> +int test_4 (int first, const char *second, float third)
> +{
> + return s4::member_1 (first, second, third); // { dg-error "no matching
> function for call to 's4::member_1\\(int&, const char\\*&, float&\\)'" }
> + /* { dg-begin-multiline-output "" }
> + return s4::member_1 (first, second, third);
> + ^
> + { dg-end-multiline-output "" } */
> + // { dg-message "candidate: 'static int s4::member_1\\(int, const
> char\\*\\*, float\\)'" "" { target *-*-* } s4_member_1 }
> + /* { dg-begin-multiline-output "" }
> + struct s4 { static int member_1 (int one, const char **two, float three); };
> + ^~~~~~~~
> + { dg-end-multiline-output "" } */
> + // { dg-message "no known conversion for argument 2 from 'const char\\*'
> to 'const char\\*\\*'" "" { target *-*-* } s4_member_1 }
> + // TODO: underline the pertinent param
> +}
> +
> +/* non-static member, with argname. */
> +
> +struct s5 { int member_1 (int one, const char **two, float three); }; // {
> dg-line s5_member_1 }
> +
> +int test_5 (int first, const char *second, float third)
> +{
> + s5 inst;
> + return inst.member_1 (first, second, third); // { dg-error "no matching
> function for call to 's5::member_1\\(int&, const char\\*&, float&\\)'" }
> + /* { dg-begin-multiline-output "" }
> + return inst.member_1 (first, second, third);
> + ^
> + { dg-end-multiline-output "" } */
> + // { dg-message "candidate: 'int s5::member_1\\(int, const char\\*\\*,
> float\\)'" "" { target *-*-* } s5_member_1 }
> + /* { dg-begin-multiline-output "" }
> + struct s5 { int member_1 (int one, const char **two, float three); };
> + ^~~~~~~~
> + { dg-end-multiline-output "" } */
> + // { dg-message "no known conversion for argument 2 from 'const char\\*'
> to 'const char\\*\\*'" "" { target *-*-* } s5_member_1 }
> + // TODO: underline the pertinent param
> +}
> +
> +/* non-static member, with argname, via a ptr. */
> +
> +struct s6 { int member_1 (int one, const char **two, float three); }; // {
> dg-line s6_member_1 }
> +
> +int test_6 (int first, const char *second, float third, s6 *ptr)
> +{
> + return ptr->member_1 (first, second, third); // { dg-error "no matching
> function for call to 's6::member_1\\(int&, const char\\*&, float&\\)'" }
> + /* { dg-begin-multiline-output "" }
> + return ptr->member_1 (first, second, third);
> + ^
> + { dg-end-multiline-output "" } */
> + // { dg-message "candidate: 'int s6::member_1\\(int, const char\\*\\*,
> float\\)'" "" { target *-*-* } s6_member_1 }
> + /* { dg-begin-multiline-output "" }
> + struct s6 { int member_1 (int one, const char **two, float three); };
> + ^~~~~~~~
> + { dg-end-multiline-output "" } */
> + // { dg-message "no known conversion for argument 2 from 'const char\\*'
> to 'const char\\*\\*'" "" { target *-*-* } s6_member_1 }
> + // TODO: underline the pertinent param
> +}
> +
> +/* Template function. */
> +
> +template <typename T>
> +int test_7 (int one, T two, float three); // { dg-line test_7_decl }
> +
> +int test_7 (int first, const char *second, float third)
> +{
> + return test_7 <const char **> (first, second, third); // { dg-line
> test_7_usage }
> + // { dg-error "no matching function" "" { target *-*-* } test_7_usage }
> + /* { dg-begin-multiline-output "" }
> + return test_7 <const char **> (first, second, third);
> + ^
> + { dg-end-multiline-output "" } */
> + // { dg-message "candidate: 'template<class T> int test_7\\(int, T,
> float\\)'" "" { target *-*-* } test_7_decl }
> + /* { dg-begin-multiline-output "" }
> + int test_7 (int one, T two, float three);
> + ^~~~~~
> + { dg-end-multiline-output "" } */
> + // { dg-message "template argument deduction/substitution failed:" "" {
> target *-*-* } test_7_decl }
> + // { dg-message "cannot convert 'second' \\(type 'const char\\*'\\) to
> type 'const char\\*\\*'" "" { target *-*-* } test_7_usage }
> + /* { dg-begin-multiline-output "" }
> + return test_7 <const char **> (first, second, third);
> + ^~~~~~
> + { dg-end-multiline-output "" } */
> +}
> +
> +/* Template class, static function. */
> +
> +template <typename T>
> +struct s8 { static int member_1 (int one, T two, float three); }; // {
> dg-line s8_member_1 }
> +
> +int test_8 (int first, const char *second, float third)
> +{
> + return s8 <const char **>::member_1 (first, second, third); // { dg-error
> "no matching function for call to 's8<const char\\*\\*>::member_1\\(int&,
> const char\\*&, float&\\)'" }
> + /* { dg-begin-multiline-output "" }
> + return s8 <const char **>::member_1 (first, second, third);
> + ^
> + { dg-end-multiline-output "" } */
> + // { dg-message "candidate: 'static int s8<T>::member_1\\(int, T,
> float\\)" "" { target *-*-* } s8_member_1 }
> + /* { dg-begin-multiline-output "" }
> + struct s8 { static int member_1 (int one, T two, float three); };
> + ^~~~~~~~
> + { dg-end-multiline-output "" } */
> + // { dg-message "no known conversion for argument 2 from 'const char\\*'
> to 'const char\\*\\*'" "" { target *-*-* } s8_member_1 }
> + // TODO: underline the pertinent param
> +}
> +
> +/* Template class, non-static function. */
> +
> +template <typename T>
> +struct s9 { int member_1 (int one, T two, float three); }; // { dg-line
> s9_member_1 }
> +
> +int test_9 (int first, const char *second, float third)
> +{
> + s9 <const char **> inst;
> + return inst.member_1 (first, second, third); // { dg-error "no matching
> function for call to 's9<const char\\*\\*>::member_1\\(int&, const char\\*&,
> float&\\)'" }
> + /* { dg-begin-multiline-output "" }
> + return inst.member_1 (first, second, third);
> + ^
> + { dg-end-multiline-output "" } */
> + // { dg-message "candidate: 'int s9<T>::member_1\\(int, T, float\\)" "" {
> target *-*-* } s9_member_1 }
> + /* { dg-begin-multiline-output "" }
> + struct s9 { int member_1 (int one, T two, float three); };
> + ^~~~~~~~
> + { dg-end-multiline-output "" } */
> + // { dg-message "no known conversion for argument 2 from 'const char\\*'
> to 'const char\\*\\*'" "" { target *-*-* } s9_member_1 }
> + // TODO: underline the pertinent param
> +}
> --
> 1.8.5.3
>
