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Reject unsafe multilevel pointer qualification conversions [EDGcpfe/28967] #455

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15 changes: 15 additions & 0 deletions src/pending_changes/edg-28967-deep-pointer-qualification.txt
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@@ -0,0 +1,15 @@
[GH #455]
GNU C++ mode: unsafe qualification conversions of multilevel pointers

In GNU C++ mode (including Clang mode), an implicit conversion between
multilevel pointer types that adds const below the first level without adding
it at every intermediate level (e.g., "char **" to "const char **") was
accepted with a warning. Such a conversion is not const-safe and is not a
valid qualification conversion; GCC and Clang reject it. It is now an error.
Conversions through array levels that the qualification conversion check does
not handle in the emulated mode are still accepted with a warning. For
example, with --g++:

void f(char **p) {
const char **q = p; // Now an error.
}
43 changes: 43 additions & 0 deletions src/types.c
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Expand Up @@ -11384,6 +11384,46 @@ conversion in C++/CLI because it drops gc-ness of an interior_ptr.

#endif /* MICROSOFT_EXTENSIONS_ALLOWED */


static a_boolean qualification_check_skips_arrays(a_type_ptr source_type,
a_type_ptr dest_type)
/*
Return TRUE if source_type or dest_type (the types pointed to by the two sides
of a pointer conversion) has an array type below some number of pointer and
pointer-to-member levels, and qualification_conversion_possible does not look
through array levels in the current mode (GNU C++ versions before 8.x and
Clang; see qualification_conversion_possible_full). In that case, a failed
qualification conversion check does not establish that a conversion that
adds qualifiers is unsafe.
*/
{
a_boolean result = FALSE;

if (gpp_version_is(<80000) || clang_mode) {
a_type_ptr tp;
int side;

for (side = 0; side < 2 && !result; side++) {
tp = side == 0 ? source_type : dest_type;
for (;;) {
tp = skip_typerefs(tp);
if (is_array(tp)) {
result = TRUE;
break;
} else if (is_pointer_or_handle(tp)) {
tp = type_pointed_to(tp);
} else if (is_ptr_to_member(tp)) {
tp = pm_member_type(tp);
} else {
break;
} /* if */
} /* for */
} /* for */
} /* if */
return result;
} /* qualification_check_skips_arrays */


a_boolean impl_pointer_conversion(
a_type_ptr source_type,
a_boolean source_is_constant,
Expand Down Expand Up @@ -11689,6 +11729,9 @@ operators), 3.3.15 (?: operator), and 3.3.16.1 (simple assignment).
std_conv->warning_suggested = warning_suggested;
qualifiers_checked = TRUE;
} else if ((!suppress_extensions || any_cfront_mode()) &&
(!gpp_mode ||
qualification_check_skips_arrays(source_type_pointed_to,
dest_type_pointed_to)) &&
same_type_with_added_qualifiers(
source_type_pointed_to,
dest_type_pointed_to,
Expand Down
8 changes: 2 additions & 6 deletions ...ts/imported/clang/cpp/CXX/dcl.dcl/dcl.spec/dcl.type/dcl.spec.auto/.p6.rto/default.1.1.txt
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Expand Up @@ -55,18 +55,14 @@ fe_only -DTEST_NUMBER=1 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
const auto **fail2(p); // expected-error {{variable 'fail2' with type 'const auto **' has incompatible initializer of type 'int **'}}
^

"Test_name.c", line 60: warning: a value of type "int **" cannot be used to initialize an entity of type "const int **"
"Test_name.c", line 60: error: a value of type "int **" cannot be used to initialize an entity of type "const int **"
const auto **fail2(p); // expected-error {{variable 'fail2' with type 'const auto **' has incompatible initializer of type 'int **'}}
^

"Test_name.c", line 60: warning: variable "p" is used before its value is set
const auto **fail2(p); // expected-error {{variable 'fail2' with type 'const auto **' has incompatible initializer of type 'int **'}}
^

"Test_name.c", line 60: warning: variable "fail2" was declared but never referenced
const auto **fail2(p); // expected-error {{variable 'fail2' with type 'const auto **' has incompatible initializer of type 'int **'}}
^

"Test_name.c", line 70: warning: "auto" as a type specifier is nonstandard in this mode
auto p1 = &S::f;
^
Expand Down Expand Up @@ -123,4 +119,4 @@ fe_only -DTEST_NUMBER=1 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
int (*funcptr2)(int) = funcptr;
^

4 errors detected in the compilation of "Test_name.c".
5 errors detected in the compilation of "Test_name.c".
8 changes: 2 additions & 6 deletions tests/tests/imported/clang/cpp/CXX/drs/.cwg23xx.rto/default.1.1.txt
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Expand Up @@ -27,11 +27,7 @@ fe_only -DTEST_NUMBER=1 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
int *const *const &f2() { return p; }
^

"Test_name.c", line 261: warning: return value type does not match the function type
const int **const &f4() { return p; }
^

"Test_name.c", line 261: warning: returning reference to local temporary
"Test_name.c", line 261: error: return value type does not match the function type
const int **const &f4() { return p; }
^

Expand Down Expand Up @@ -59,4 +55,4 @@ fe_only -DTEST_NUMBER=1 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
const A a;
^

10 errors detected in the compilation of "Test_name.c".
11 errors detected in the compilation of "Test_name.c".
8 changes: 2 additions & 6 deletions tests/tests/imported/clang/cpp/CXX/drs/.cwg23xx.rto/default.2.1.txt
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Expand Up @@ -37,11 +37,7 @@ fe_only -DTEST_NUMBER=2 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
int *const *const &f2() { return p; }
^

"Test_name.c", line 261: warning: return value type does not match the function type
const int **const &f4() { return p; }
^

"Test_name.c", line 261: warning: returning reference to local temporary
"Test_name.c", line 261: error: return value type does not match the function type
const int **const &f4() { return p; }
^

Expand Down Expand Up @@ -92,4 +88,4 @@ fe_only -DTEST_NUMBER=2 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
const A a;
^

14 errors detected in the compilation of "Test_name.c".
15 errors detected in the compilation of "Test_name.c".
8 changes: 2 additions & 6 deletions tests/tests/imported/clang/cpp/CXX/drs/.cwg23xx.rto/default.3.1.txt
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Expand Up @@ -37,11 +37,7 @@ fe_only -DTEST_NUMBER=3 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
int *const *const &f2() { return p; }
^

"Test_name.c", line 261: warning: return value type does not match the function type
const int **const &f4() { return p; }
^

"Test_name.c", line 261: warning: returning reference to local temporary
"Test_name.c", line 261: error: return value type does not match the function type
const int **const &f4() { return p; }
^

Expand Down Expand Up @@ -96,4 +92,4 @@ fe_only -DTEST_NUMBER=3 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
const A a;
^

15 errors detected in the compilation of "Test_name.c".
16 errors detected in the compilation of "Test_name.c".
8 changes: 2 additions & 6 deletions tests/tests/imported/clang/cpp/CXX/drs/.cwg23xx.rto/default.4.1.txt
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Expand Up @@ -27,11 +27,7 @@ fe_only -DTEST_NUMBER=4 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
int *const *const &f2() { return p; }
^

"Test_name.c", line 261: warning: return value type does not match the function type
const int **const &f4() { return p; }
^

"Test_name.c", line 261: warning: returning reference to local temporary
"Test_name.c", line 261: error: return value type does not match the function type
const int **const &f4() { return p; }
^

Expand Down Expand Up @@ -102,4 +98,4 @@ fe_only -DTEST_NUMBER=4 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
const A a;
^

17 errors detected in the compilation of "Test_name.c".
18 errors detected in the compilation of "Test_name.c".
8 changes: 2 additions & 6 deletions tests/tests/imported/clang/cpp/CXX/drs/.cwg23xx.rto/default.5.1.txt
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Expand Up @@ -27,11 +27,7 @@ fe_only -DTEST_NUMBER=5 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
int *const *const &f2() { return p; }
^

"Test_name.c", line 261: warning: return value type does not match the function type
const int **const &f4() { return p; }
^

"Test_name.c", line 261: warning: returning reference to local temporary
"Test_name.c", line 261: error: return value type does not match the function type
const int **const &f4() { return p; }
^

Expand Down Expand Up @@ -152,4 +148,4 @@ fe_only -DTEST_NUMBER=5 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
const A a;
^

20 errors detected in the compilation of "Test_name.c".
21 errors detected in the compilation of "Test_name.c".
8 changes: 2 additions & 6 deletions tests/tests/imported/clang/cpp/CXX/drs/.cwg23xx.rto/default.6.1.txt
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Expand Up @@ -27,11 +27,7 @@ fe_only -DTEST_NUMBER=6 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
int *const *const &f2() { return p; }
^

"Test_name.c", line 261: warning: return value type does not match the function type
const int **const &f4() { return p; }
^

"Test_name.c", line 261: warning: returning reference to local temporary
"Test_name.c", line 261: error: return value type does not match the function type
const int **const &f4() { return p; }
^

Expand Down Expand Up @@ -152,4 +148,4 @@ fe_only -DTEST_NUMBER=6 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
const A a;
^

20 errors detected in the compilation of "Test_name.c".
21 errors detected in the compilation of "Test_name.c".
8 changes: 2 additions & 6 deletions tests/tests/imported/clang/cpp/CXX/drs/.cwg23xx.rto/default.7.1.txt
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Expand Up @@ -27,11 +27,7 @@ fe_only -DTEST_NUMBER=7 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
int *const *const &f2() { return p; }
^

"Test_name.c", line 261: warning: return value type does not match the function type
const int **const &f4() { return p; }
^

"Test_name.c", line 261: warning: returning reference to local temporary
"Test_name.c", line 261: error: return value type does not match the function type
const int **const &f4() { return p; }
^

Expand Down Expand Up @@ -152,4 +148,4 @@ fe_only -DTEST_NUMBER=7 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
const A a;
^

20 errors detected in the compilation of "Test_name.c".
21 errors detected in the compilation of "Test_name.c".
4 changes: 2 additions & 2 deletions tests/tests/imported/clang/cpp/CXX/drs/.cwg3xx.rto/default.1.1.txt
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Expand Up @@ -789,7 +789,7 @@ fe_only -DTEST_NUMBER=1 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
^
detected during instantiation of "void cwg345::f(T) [with T=cwg345::A]" at line 753

"Test_name.c", line 787: warning: return value type does not match the function type
"Test_name.c", line 787: error: return value type does not match the function type
return p;
^
detected during instantiation of "cwg349::A::operator T ***() [with T=const int]" at line 796
Expand Down Expand Up @@ -849,4 +849,4 @@ fe_only -DTEST_NUMBER=1 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
const A b(a);
^

154 errors detected in the compilation of "Test_name.c".
155 errors detected in the compilation of "Test_name.c".
4 changes: 2 additions & 2 deletions tests/tests/imported/clang/cpp/CXX/drs/.cwg3xx.rto/default.2.1.txt
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Expand Up @@ -751,7 +751,7 @@ fe_only -DTEST_NUMBER=2 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
^
detected during instantiation of "void cwg345::f(T) [with T=cwg345::A]" at line 753

"Test_name.c", line 787: warning: return value type does not match the function type
"Test_name.c", line 787: error: return value type does not match the function type
return p;
^
detected during instantiation of "cwg349::A::operator T ***() [with T=const int]" at line 796
Expand Down Expand Up @@ -831,4 +831,4 @@ fe_only -DTEST_NUMBER=2 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
extern WithoutLinkage5 withoutLinkage5;
^

155 errors detected in the compilation of "Test_name.c".
156 errors detected in the compilation of "Test_name.c".
4 changes: 2 additions & 2 deletions tests/tests/imported/clang/cpp/CXX/drs/.cwg3xx.rto/default.3.1.txt
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Expand Up @@ -743,7 +743,7 @@ fe_only -DTEST_NUMBER=3 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
^
detected during instantiation of "void cwg345::f(T) [with T=cwg345::A]" at line 753

"Test_name.c", line 787: warning: return value type does not match the function type
"Test_name.c", line 787: error: return value type does not match the function type
return p;
^
detected during instantiation of "cwg349::A::operator T ***() [with T=const int]" at line 796
Expand Down Expand Up @@ -823,4 +823,4 @@ fe_only -DTEST_NUMBER=3 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
extern WithoutLinkage5 withoutLinkage5;
^

155 errors detected in the compilation of "Test_name.c".
156 errors detected in the compilation of "Test_name.c".
4 changes: 2 additions & 2 deletions tests/tests/imported/clang/cpp/CXX/drs/.cwg3xx.rto/default.4.1.txt
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Expand Up @@ -739,7 +739,7 @@ fe_only -DTEST_NUMBER=4 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
^
detected during instantiation of "void cwg345::f(T) [with T=cwg345::A]" at line 753

"Test_name.c", line 787: warning: return value type does not match the function type
"Test_name.c", line 787: error: return value type does not match the function type
return p;
^
detected during instantiation of "cwg349::A::operator T ***() [with T=const int]" at line 796
Expand Down Expand Up @@ -819,4 +819,4 @@ fe_only -DTEST_NUMBER=4 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
extern WithoutLinkage5 withoutLinkage5;
^

155 errors detected in the compilation of "Test_name.c".
156 errors detected in the compilation of "Test_name.c".
4 changes: 2 additions & 2 deletions tests/tests/imported/clang/cpp/CXX/drs/.cwg3xx.rto/default.5.1.txt
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Expand Up @@ -739,7 +739,7 @@ fe_only -DTEST_NUMBER=5 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
^
detected during instantiation of "void cwg345::f(T) [with T=cwg345::A]" at line 753

"Test_name.c", line 787: warning: return value type does not match the function type
"Test_name.c", line 787: error: return value type does not match the function type
return p;
^
detected during instantiation of "cwg349::A::operator T ***() [with T=const int]" at line 796
Expand Down Expand Up @@ -819,4 +819,4 @@ fe_only -DTEST_NUMBER=5 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
extern WithoutLinkage5 withoutLinkage5;
^

156 errors detected in the compilation of "Test_name.c".
157 errors detected in the compilation of "Test_name.c".
4 changes: 2 additions & 2 deletions tests/tests/imported/clang/cpp/CXX/drs/.cwg3xx.rto/default.6.1.txt
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Expand Up @@ -739,7 +739,7 @@ fe_only -DTEST_NUMBER=6 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
^
detected during instantiation of "void cwg345::f(T) [with T=cwg345::A]" at line 753

"Test_name.c", line 787: warning: return value type does not match the function type
"Test_name.c", line 787: error: return value type does not match the function type
return p;
^
detected during instantiation of "cwg349::A::operator T ***() [with T=const int]" at line 796
Expand Down Expand Up @@ -819,4 +819,4 @@ fe_only -DTEST_NUMBER=6 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
extern WithoutLinkage5 withoutLinkage5;
^

156 errors detected in the compilation of "Test_name.c".
157 errors detected in the compilation of "Test_name.c".
4 changes: 2 additions & 2 deletions tests/tests/imported/clang/cpp/CXX/drs/.cwg3xx.rto/default.7.1.txt
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Expand Up @@ -739,7 +739,7 @@ fe_only -DTEST_NUMBER=7 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
^
detected during instantiation of "void cwg345::f(T) [with T=cwg345::A]" at line 753

"Test_name.c", line 787: warning: return value type does not match the function type
"Test_name.c", line 787: error: return value type does not match the function type
return p;
^
detected during instantiation of "cwg349::A::operator T ***() [with T=const int]" at line 796
Expand Down Expand Up @@ -819,4 +819,4 @@ fe_only -DTEST_NUMBER=7 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
extern WithoutLinkage5 withoutLinkage5;
^

156 errors detected in the compilation of "Test_name.c".
157 errors detected in the compilation of "Test_name.c".
4 changes: 2 additions & 2 deletions tests/tests/imported/clang/cpp/CXX/drs/.cwg3xx.rto/edg_x86_32.1.1.txt
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Expand Up @@ -789,7 +789,7 @@ fe_only -DTEST_NUMBER=1 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
^
detected during instantiation of "void cwg345::f(T) [with T=cwg345::A]" at line 753

"Test_name.c", line 787: warning: return value type does not match the function type
"Test_name.c", line 787: error: return value type does not match the function type
return p;
^
detected during instantiation of "cwg349::A::operator T ***() [with T=const int]" at line 796
Expand Down Expand Up @@ -849,4 +849,4 @@ fe_only -DTEST_NUMBER=1 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
const A b(a);
^

153 errors detected in the compilation of "Test_name.c".
154 errors detected in the compilation of "Test_name.c".
4 changes: 2 additions & 2 deletions tests/tests/imported/clang/cpp/CXX/drs/.cwg3xx.rto/edg_x86_32.2.1.txt
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Expand Up @@ -751,7 +751,7 @@ fe_only -DTEST_NUMBER=2 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
^
detected during instantiation of "void cwg345::f(T) [with T=cwg345::A]" at line 753

"Test_name.c", line 787: warning: return value type does not match the function type
"Test_name.c", line 787: error: return value type does not match the function type
return p;
^
detected during instantiation of "cwg349::A::operator T ***() [with T=const int]" at line 796
Expand Down Expand Up @@ -831,4 +831,4 @@ fe_only -DTEST_NUMBER=2 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
extern WithoutLinkage5 withoutLinkage5;
^

154 errors detected in the compilation of "Test_name.c".
155 errors detected in the compilation of "Test_name.c".
4 changes: 2 additions & 2 deletions tests/tests/imported/clang/cpp/CXX/drs/.cwg3xx.rto/edg_x86_32.3.1.txt
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Expand Up @@ -743,7 +743,7 @@ fe_only -DTEST_NUMBER=3 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
^
detected during instantiation of "void cwg345::f(T) [with T=cwg345::A]" at line 753

"Test_name.c", line 787: warning: return value type does not match the function type
"Test_name.c", line 787: error: return value type does not match the function type
return p;
^
detected during instantiation of "cwg349::A::operator T ***() [with T=const int]" at line 796
Expand Down Expand Up @@ -823,4 +823,4 @@ fe_only -DTEST_NUMBER=3 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
extern WithoutLinkage5 withoutLinkage5;
^

154 errors detected in the compilation of "Test_name.c".
155 errors detected in the compilation of "Test_name.c".
4 changes: 2 additions & 2 deletions tests/tests/imported/clang/cpp/CXX/drs/.cwg3xx.rto/edg_x86_32.4.1.txt
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Expand Up @@ -739,7 +739,7 @@ fe_only -DTEST_NUMBER=4 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
^
detected during instantiation of "void cwg345::f(T) [with T=cwg345::A]" at line 753

"Test_name.c", line 787: warning: return value type does not match the function type
"Test_name.c", line 787: error: return value type does not match the function type
return p;
^
detected during instantiation of "cwg349::A::operator T ***() [with T=const int]" at line 796
Expand Down Expand Up @@ -819,4 +819,4 @@ fe_only -DTEST_NUMBER=4 --clang -tused -e 200 --no_wrap_diagnostics --clang_vers
extern WithoutLinkage5 withoutLinkage5;
^

154 errors detected in the compilation of "Test_name.c".
155 errors detected in the compilation of "Test_name.c".
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