On 11/13/23 14:01, Jonathan Wakely wrote:
Tested x86_64-linux. Does this make sense for trunk?
OK, thanks.
These forbidden conversions are defined as narrowing conversions, and we
already use -Wnarrowing to control other "ill-formed, but only warn by
default" diagnostics required by the standard.
-- >8 --
Several users have been confused by the status of these warnings,
which can be misunderstood as "this might not be what you want",
rather than diagnostics required by the C++ standard. Add the text "ISO
C++ does not allow" to make this clear.
Also link them to -Wnarrowing so that they can be disabled or promoted
to errors independently of other pedwarns.
gcc/cp/ChangeLog:
PR c++/111842
PR c++/112498
* call.cc (convert_like_internal): Use OPT_Wnarrowing for
pedwarns about illformed conversions involving extended
floating-point types. Clarify that ISO C++ requires these
diagnostics.
* g++.dg/cpp23/ext-floating16.C: New test.
* g++.dg/cpp23/ext-floating17.C: New test.
---
gcc/cp/call.cc | 10 +++--
gcc/testsuite/g++.dg/cpp23/ext-floating16.C | 40 ++++++++++++++++++++
gcc/testsuite/g++.dg/cpp23/ext-floating17.C | 42 +++++++++++++++++++++
3 files changed, 88 insertions(+), 4 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp23/ext-floating16.C
create mode 100644 gcc/testsuite/g++.dg/cpp23/ext-floating17.C
diff --git a/gcc/cp/call.cc b/gcc/cp/call.cc
index 4516677bcab..4b0c6c42f01 100644
--- a/gcc/cp/call.cc
+++ b/gcc/cp/call.cc
@@ -8303,15 +8303,17 @@ convert_like_internal (conversion *convs, tree expr,
tree fn, int argnum,
totype))
{
case 2:
- if (pedwarn (loc, 0, "converting to %qH from %qI with greater "
- "conversion rank", totype, TREE_TYPE (expr)))
+ if (pedwarn (loc, OPT_Wnarrowing, "ISO C++ does not allow "
+ "converting to %qH from %qI with greater "
+ "conversion rank", totype, TREE_TYPE (expr)))
complained = 1;
else if (!complained)
complained = -1;
break;
case 3:
- if (pedwarn (loc, 0, "converting to %qH from %qI with unordered "
- "conversion ranks", totype, TREE_TYPE (expr)))
+ if (pedwarn (loc, OPT_Wnarrowing, "ISO C++ does not allow "
+ "converting to %qH from %qI with unordered "
+ "conversion rank", totype, TREE_TYPE (expr)))
complained = 1;
else if (!complained)
complained = -1;
diff --git a/gcc/testsuite/g++.dg/cpp23/ext-floating16.C
b/gcc/testsuite/g++.dg/cpp23/ext-floating16.C
new file mode 100644
index 00000000000..d6a562d5cb0
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp23/ext-floating16.C
@@ -0,0 +1,40 @@
+// P1467R9 - Extended floating-point types and standard names.
+// { dg-do compile { target c++23 } }
+// { dg-options "-pedantic-errors -Wno-narrowing" }
+// { dg-add-options float16 }
+// { dg-add-options float32 }
+// { dg-add-options float64 }
+// { dg-add-options float128 }
+
+#include "ext-floating.h"
+
+#ifdef __STRICT_ANSI__
+#undef __SIZEOF_FLOAT128__
+#endif
+
+using namespace std;
+
+#ifdef __STDCPP_FLOAT16_T__
+#ifdef __STDCPP_FLOAT32_T__
+float16_t f16c = 1.0F32; // { dg-bogus "converting to 'std::float16_t' \\\{aka
'_Float16'\\\} from '_Float32' with greater conversion rank" "" { target { float16
&& float32 } } }
+#endif
+#ifdef __STDCPP_FLOAT64_T__
+float16_t f16e = 1.0F64; // { dg-bogus "converting to 'std::float16_t' \\\{aka
'_Float16'\\\} from '_Float64' with greater conversion rank" "" { target { float16
&& float64 } } }
+#endif
+#ifdef __STDCPP_FLOAT128_T__
+float16_t f16g = 1.0F128; // { dg-bogus "converting to 'std::float16_t' \\\{aka
'_Float16'\\\} from '_Float128' with greater conversion rank" "" { target { float16
&& float128 } } }
+#endif
+#endif
+#ifdef __STDCPP_FLOAT32_T__
+#ifdef __STDCPP_FLOAT64_T__
+float32_t f32e = 1.0F64; // { dg-bogus "converting to 'std::float32_t' \\\{aka
'_Float32'\\\} from '_Float64' with greater conversion rank" "" { target { float32
&& float64 } } }
+#endif
+#ifdef __STDCPP_FLOAT128_T__
+float32_t f32g = 1.0F128; // { dg-bogus "converting to 'std::float32_t' \\\{aka
'_Float32'\\\} from '_Float128' with greater conversion rank" "" { target { float32
&& float128 } } }
+#endif
+#endif
+#ifdef __STDCPP_FLOAT64_T__
+#ifdef __STDCPP_FLOAT128_T__
+float64_t f64g = 1.0F128; // { dg-bogus "converting to 'std::float64_t' \\\{aka
'_Float64'\\\} from '_Float128' with greater conversion rank" "" { target { float64
&& float128 } } }
+#endif
+#endif
diff --git a/gcc/testsuite/g++.dg/cpp23/ext-floating17.C
b/gcc/testsuite/g++.dg/cpp23/ext-floating17.C
new file mode 100644
index 00000000000..796e045537a
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp23/ext-floating17.C
@@ -0,0 +1,42 @@
+// P1467R9 - Extended floating-point types and standard names.
+// { dg-do compile { target c++23 } }
+// { dg-options "-Werror=narrowing" }
+// { dg-add-options float16 }
+// { dg-add-options float32 }
+// { dg-add-options float64 }
+// { dg-add-options float128 }
+// { dg-prune-output "some warnings being treated as errors" }
+
+#include "ext-floating.h"
+
+#ifdef __STRICT_ANSI__
+#undef __SIZEOF_FLOAT128__
+#endif
+
+using namespace std;
+
+#ifdef __STDCPP_FLOAT16_T__
+#ifdef __STDCPP_FLOAT32_T__
+float16_t f16c = 1.0F32; // { dg-error "converting to 'std::float16_t' \\\{aka
'_Float16'\\\} from '_Float32' with greater conversion rank" "" { target { float16
&& float32 } } }
+#endif
+#ifdef __STDCPP_FLOAT64_T__
+float16_t f16e = 1.0F64; // { dg-error "converting to 'std::float16_t' \\\{aka
'_Float16'\\\} from '_Float64' with greater conversion rank" "" { target { float16
&& float64 } } }
+#endif
+#ifdef __STDCPP_FLOAT128_T__
+float16_t f16g = 1.0F128; // { dg-error "converting to 'std::float16_t' \\\{aka
'_Float16'\\\} from '_Float128' with greater conversion rank" "" { target { float16
&& float128 } } }
+#endif
+#endif
+#ifdef __STDCPP_FLOAT32_T__
+#ifdef __STDCPP_FLOAT64_T__
+float32_t f32e = 1.0F64; // { dg-error "converting to 'std::float32_t' \\\{aka
'_Float32'\\\} from '_Float64' with greater conversion rank" "" { target { float32
&& float64 } } }
+#endif
+#ifdef __STDCPP_FLOAT128_T__
+float32_t f32g = 1.0F128; // { dg-error "converting to 'std::float32_t' \\\{aka
'_Float32'\\\} from '_Float128' with greater conversion rank" "" { target { float32
&& float128 } } }
+#endif
+#endif
+#ifdef __STDCPP_FLOAT64_T__
+#ifdef __STDCPP_FLOAT128_T__
+float64_t f64g = 1.0F128; // { dg-error "converting to 'std::float64_t' \\\{aka
'_Float64'\\\} from '_Float128' with greater conversion rank" "" { target { float64
&& float128 } } }
+#endif
+#endif
+
