[clang] 2bd8493 - Improve type printing of const arrays to normalize array-of-const and const-array
Richard Smith via cfe-commits
cfe-commits at lists.llvm.org
Mon Oct 11 14:46:31 PDT 2021
On Wed, 15 Sept 2021 at 13:52, David Blaikie <dblaikie at gmail.com> wrote:
> On Tue, Sep 14, 2021 at 10:04 AM Richard Smith <richard at metafoo.co.uk>
> wrote:
>
>> On Mon, 13 Sept 2021 at 19:24, David Blaikie via cfe-commits <
>> cfe-commits at lists.llvm.org> wrote:
>>
>>>
>>> Author: David Blaikie
>>> Date: 2021-09-13T19:17:05-07:00
>>> New Revision: 2bd84938470bf2e337801faafb8a67710f46429d
>>>
>>> URL:
>>> https://github.com/llvm/llvm-project/commit/2bd84938470bf2e337801faafb8a67710f46429d
>>> DIFF:
>>> https://github.com/llvm/llvm-project/commit/2bd84938470bf2e337801faafb8a67710f46429d.diff
>>>
>>> LOG: Improve type printing of const arrays to normalize array-of-const
>>> and const-array
>>>
>>> Since these map to the same effective type - render them the same/in the
>>> more legible way (const x[n]).
>>>
>>
>> Nice!
>>
>>
>>> Added:
>>>
>>>
>>> Modified:
>>> clang/lib/AST/TypePrinter.cpp
>>> clang/test/ARCMT/cxx-checking.mm
>>> clang/test/AST/ast-dump-APValue-arithmetic.cpp
>>> clang/test/AST/ast-dump-APValue-array.cpp
>>> clang/test/CXX/basic/basic.types/p10.cpp
>>> clang/test/Sema/assign.c
>>> clang/test/Sema/typedef-retain.c
>>> clang/test/SemaCXX/reinterpret-cast.cpp
>>> clang/test/SemaCXX/static-assert-cxx17.cpp
>>>
>>> Removed:
>>>
>>>
>>>
>>>
>>> ################################################################################
>>> diff --git a/clang/lib/AST/TypePrinter.cpp
>>> b/clang/lib/AST/TypePrinter.cpp
>>> index aef1e4f3f4953..251db97c7db08 100644
>>> --- a/clang/lib/AST/TypePrinter.cpp
>>> +++ b/clang/lib/AST/TypePrinter.cpp
>>> @@ -200,11 +200,12 @@ bool TypePrinter::canPrefixQualifiers(const Type
>>> *T,
>>> // type expands to a simple string.
>>> bool CanPrefixQualifiers = false;
>>> NeedARCStrongQualifier = false;
>>> - Type::TypeClass TC = T->getTypeClass();
>>> + const Type *UnderlyingType = T;
>>> if (const auto *AT = dyn_cast<AutoType>(T))
>>> - TC = AT->desugar()->getTypeClass();
>>> + UnderlyingType = AT->desugar().getTypePtr();
>>> if (const auto *Subst = dyn_cast<SubstTemplateTypeParmType>(T))
>>> - TC = Subst->getReplacementType()->getTypeClass();
>>> + UnderlyingType = Subst->getReplacementType().getTypePtr();
>>> + Type::TypeClass TC = UnderlyingType->getTypeClass();
>>>
>>> switch (TC) {
>>> case Type::Auto:
>>> @@ -243,6 +244,9 @@ bool TypePrinter::canPrefixQualifiers(const Type *T,
>>>
>>> case Type::ConstantArray:
>>> case Type::IncompleteArray:
>>> + return canPrefixQualifiers(
>>> +
>>> cast<ArrayType>(UnderlyingType)->getElementType().getTypePtr(),
>>> + NeedARCStrongQualifier);
>>> case Type::VariableArray:
>>> case Type::DependentSizedArray:
>>>
>>
>> Can we give these two cases the same treatment?
>>
>
> Handled the DependentSizedArray in
> https://github.com/llvm/llvm-project/commit/40acc0adad59ac39e9a7a02fcd93161298500c00
>
> But per the comment in that commit I wasn't able to reproduce the problem
> with a variable array - though we could include it in the handling on
> principle/for consistency, even without a test/etc. Perhaps there's a way
> to test/provoke the behavior you might know that I couldn't figure out?
>
> Details from the commit:
>
> The VariableArray case I couldn't figure out how to test/provoke - you
>
> can't write/form a variable array in any context other than a local
>
> variable that I know of, and in that case `const int x[n]` is the
>
> normalized form already (array-of-const) and you can't use typedefs
>
> (since you can't typedef int[n] with variable 'n') to force the
>
> const-array AST that would produce the undesirable type printing "int
>
> const [n]".
>
C has a fairly surprising rule here -- you actually can define a VLA type
in a local typedef. For example,
void f(int n) {
typedef int arr[n];
const arr x;
}
... is valid in C. In C++ mode, this produces:
<source>:3:15: error: default initialization of an object of const type
'const arr' (aka 'int const[n]')
(note, 'int const[n]' not 'const int[n]').
> Oh, also - another quirk of array type printing that I'd be up for
> addressing if you've got an opinion on it:
>
> "int [n]" is printed with a space between the "int" and array.
> "int *const[n]" is printed without a space before the array (though both
> have a space after "int")
>
> ClangFormat formats these as "int[n]" and "int *const[n]" - with *
> left/right depending on ClangFormat's heuristics/configuration.
>
> Reckon we should remove the space in "int[n]"?
>
I think we should make it consistent, one way or the other. Beyond that,
the decision seems somewhat arbitrary, but following clang-format seems
reasonable to me. I certainly would expect `int *[n]` rather than `int *
[n]`, which similarly suggests omitting the space here.
NeedARCStrongQualifier = true;
>>
>>
>>> diff --git a/clang/test/ARCMT/cxx-checking.mm b/clang/test/ARCMT/
>>> cxx-checking.mm
>>> index 952f3cdcbb79c..d6441def09b40 100644
>>> --- a/clang/test/ARCMT/cxx-checking.mm
>>> +++ b/clang/test/ARCMT/cxx-checking.mm
>>> @@ -80,7 +80,7 @@
>>>
>>> struct FlexibleArrayMember0 {
>>> int length;
>>> - id array[]; // expected-error{{flexible array member 'array' of type
>>> 'id __strong[]' with non-trivial destruction}}
>>> + id array[]; // expected-error{{flexible array member 'array' of type
>>> '__strong id []' with non-trivial destruction}}
>>> };
>>>
>>> struct FlexibleArrayMember1 {
>>>
>>> diff --git a/clang/test/AST/ast-dump-APValue-arithmetic.cpp
>>> b/clang/test/AST/ast-dump-APValue-arithmetic.cpp
>>> index 835d8c8108346..e51c1cee04cfe 100644
>>> --- a/clang/test/AST/ast-dump-APValue-arithmetic.cpp
>>> +++ b/clang/test/AST/ast-dump-APValue-arithmetic.cpp
>>> @@ -36,13 +36,13 @@ void Test() {
>>> // CHECK-NEXT: | |-value: ComplexFloat 3.141500e+00 + 4.200000e+01i
>>>
>>> constexpr _Complex int ArrayOfComplexInt[10] = {ComplexInt,
>>> ComplexInt, ComplexInt, ComplexInt};
>>> - // CHECK: | `-VarDecl {{.*}} <col:{{.*}}, col:{{.*}}> col:{{.*}}
>>> ArrayOfComplexInt '_Complex int const[10]' constexpr cinit
>>> + // CHECK: | `-VarDecl {{.*}} <col:{{.*}}, col:{{.*}}> col:{{.*}}
>>> ArrayOfComplexInt 'const _Complex int [10]' constexpr cinit
>>> // CHECK-NEXT: | |-value: Array size=10
>>> // CHECK-NEXT: | | |-elements: ComplexInt 42 + 24i, ComplexInt 42
>>> + 24i, ComplexInt 42 + 24i, ComplexInt 42 + 24i
>>> // CHECK-NEXT: | | `-filler: 6 x ComplexInt 0 + 0i
>>>
>>> constexpr _Complex float ArrayOfComplexFloat[10] = {ComplexFloat,
>>> ComplexFloat, ComplexInt, ComplexInt};
>>> - // CHECK: `-VarDecl {{.*}} <col:{{.*}}, col:{{.*}}> col:{{.*}}
>>> ArrayOfComplexFloat '_Complex float const[10]' constexpr cinit
>>> + // CHECK: `-VarDecl {{.*}} <col:{{.*}}, col:{{.*}}> col:{{.*}}
>>> ArrayOfComplexFloat 'const _Complex float [10]' constexpr cinit
>>> // CHECK-NEXT: |-value: Array size=10
>>> // CHECK-NEXT: | |-elements: ComplexFloat 3.141500e+00 +
>>> 4.200000e+01i, ComplexFloat 3.141500e+00 + 4.200000e+01i, ComplexFloat
>>> 4.200000e+01 + 2.400000e+01i, ComplexFloat 4.200000e+01 + 2.400000e+01i
>>> // CHECK-NEXT: | `-filler: 6 x ComplexFloat 0.000000e+00 +
>>> 0.000000e+00i
>>>
>>> diff --git a/clang/test/AST/ast-dump-APValue-array.cpp
>>> b/clang/test/AST/ast-dump-APValue-array.cpp
>>> index f9b38ec332a5b..72e519208ac56 100644
>>> --- a/clang/test/AST/ast-dump-APValue-array.cpp
>>> +++ b/clang/test/AST/ast-dump-APValue-array.cpp
>>> @@ -43,7 +43,7 @@ void Test() {
>>> constexpr float arr_f[3][5] = {
>>> {1, 2, 3, 4, 5},
>>> };
>>> - // CHECK: | `-VarDecl {{.*}} <line:{{.*}}, line:{{.*}}> line:{{.*}}
>>> arr_f 'float const[3][5]' constexpr cinit
>>> + // CHECK: | `-VarDecl {{.*}} <line:{{.*}}, line:{{.*}}> line:{{.*}}
>>> arr_f 'const float [3][5]' constexpr cinit
>>> // CHECK-NEXT: | |-value: Array size=3
>>> // CHECK-NEXT: | | |-element: Array size=5
>>> // CHECK-NEXT: | | | |-elements: Float 1.000000e+00, Float
>>> 2.000000e+00, Float 3.000000e+00, Float 4.000000e+00
>>> @@ -52,7 +52,7 @@ void Test() {
>>> // CHECK-NEXT: | | `-filler: 5 x Float 0.000000e+00
>>>
>>> constexpr S0 arr_s0[2] = {{1, 2}, {3, 4}};
>>> - // CHECK: | `-VarDecl {{.*}} <col:{{.*}}, col:{{.*}}> col:{{.*}}
>>> arr_s0 'S0 const[2]' constexpr cinit
>>> + // CHECK: | `-VarDecl {{.*}} <col:{{.*}}, col:{{.*}}> col:{{.*}}
>>> arr_s0 'const S0 [2]' constexpr cinit
>>> // CHECK-NEXT: | |-value: Array size=2
>>> // CHECK-NEXT: | | |-element: Struct
>>> // CHECK-NEXT: | | | `-field: Array size=2
>>> @@ -62,12 +62,12 @@ void Test() {
>>> // CHECK-NEXT: | | `-elements: Int 3, Int 4
>>>
>>> constexpr U0 arr_u0[2] = {{.i = 42}, {.f = 3.1415f}};
>>> - // CHECK: | `-VarDecl {{.*}} <col:{{.*}}, col:{{.*}}> col:{{.*}}
>>> arr_u0 'U0 const[2]' constexpr cinit
>>> + // CHECK: | `-VarDecl {{.*}} <col:{{.*}}, col:{{.*}}> col:{{.*}}
>>> arr_u0 'const U0 [2]' constexpr cinit
>>> // CHECK-NEXT: | |-value: Array size=2
>>> // CHECK-NEXT: | | `-elements: Union .i Int 42, Union .f Float
>>> 3.141500e+00
>>>
>>> constexpr S1 arr_s1[2] = {};
>>> - // CHECK: `-VarDecl {{.*}} <col:{{.*}}, col:{{.*}}> col:{{.*}}
>>> arr_s1 'S1 const[2]' constexpr cinit
>>> + // CHECK: `-VarDecl {{.*}} <col:{{.*}}, col:{{.*}}> col:{{.*}}
>>> arr_s1 'const S1 [2]' constexpr cinit
>>> // CHECK-NEXT: |-value: Array size=2
>>> // CHECK-NEXT: | |-element: Struct
>>> // CHECK-NEXT: | | |-field: Struct
>>>
>>> diff --git a/clang/test/CXX/basic/basic.types/p10.cpp
>>> b/clang/test/CXX/basic/basic.types/p10.cpp
>>> index aac07c76bed2e..eae0c6513ac24 100644
>>> --- a/clang/test/CXX/basic/basic.types/p10.cpp
>>> +++ b/clang/test/CXX/basic/basic.types/p10.cpp
>>> @@ -32,7 +32,7 @@ struct Incomplete; // expected-note 2{{forward
>>> declaration of 'Incomplete'}}
>>> template<class T> struct ClassTemp {};
>>>
>>> constexpr Incomplete incomplete = {}; // expected-error {{constexpr
>>> variable cannot have non-literal type 'const Incomplete'}} expected-note
>>> {{incomplete type 'const Incomplete' is not a literal type}}
>>> -constexpr Incomplete incomplete2[] = {}; // expected-error {{constexpr
>>> variable cannot have non-literal type 'Incomplete const[]'}} expected-note
>>> {{incomplete type 'Incomplete const[]' is not a literal type}}
>>> +constexpr Incomplete incomplete2[] = {}; // expected-error {{constexpr
>>> variable cannot have non-literal type 'const Incomplete []'}} expected-note
>>> {{incomplete type 'const Incomplete []' is not a literal type}}
>>> constexpr ClassTemp<int> classtemplate = {};
>>> constexpr ClassTemp<int> classtemplate2[] = {};
>>>
>>>
>>> diff --git a/clang/test/Sema/assign.c b/clang/test/Sema/assign.c
>>> index 3edd5d4feaf2e..d65f9bf26547e 100644
>>> --- a/clang/test/Sema/assign.c
>>> +++ b/clang/test/Sema/assign.c
>>> @@ -13,7 +13,7 @@ typedef int arr[10];
>>> void test3() {
>>> const arr b; // expected-note {{variable 'b' declared const
>>> here}}
>>> const int b2[10]; // expected-note {{variable 'b2' declared const
>>> here}}
>>> - b[4] = 1; // expected-error {{cannot assign to variable 'b'
>>> with const-qualified type 'const arr' (aka 'int const[10]')}}
>>> + b[4] = 1; // expected-error {{cannot assign to variable 'b'
>>> with const-qualified type 'const arr' (aka 'const int [10]')}}
>>> b2[4] = 1; // expected-error {{cannot assign to variable 'b2'
>>> with const-qualified type 'const int [10]'}}
>>> }
>>>
>>>
>>> diff --git a/clang/test/Sema/typedef-retain.c
>>> b/clang/test/Sema/typedef-retain.c
>>> index 70e2abc1da5b8..d4358bce5ee5b 100644
>>> --- a/clang/test/Sema/typedef-retain.c
>>> +++ b/clang/test/Sema/typedef-retain.c
>>> @@ -17,7 +17,7 @@ typedef int a[5];
>>> void test3() {
>>> typedef const a b;
>>> b r; // expected-note {{variable 'r' declared const here}}
>>> - r[0] = 10; // expected-error {{cannot assign to variable 'r' with
>>> const-qualified type 'b' (aka 'int const[5]')}}
>>> + r[0] = 10; // expected-error {{cannot assign to variable 'r' with
>>> const-qualified type 'b' (aka 'const int [5]')}}
>>> }
>>>
>>> int test4(const a y) {
>>>
>>> diff --git a/clang/test/SemaCXX/reinterpret-cast.cpp
>>> b/clang/test/SemaCXX/reinterpret-cast.cpp
>>> index 6a4bc91665448..f427af1efbafc 100644
>>> --- a/clang/test/SemaCXX/reinterpret-cast.cpp
>>> +++ b/clang/test/SemaCXX/reinterpret-cast.cpp
>>> @@ -132,7 +132,7 @@ void const_arrays() {
>>> const STRING *s;
>>> const char *c;
>>>
>>> - (void)reinterpret_cast<char *>(s); // expected-error
>>> {{reinterpret_cast from 'const STRING *' (aka 'char const (*)[10]') to
>>> 'char *' casts away qualifiers}}
>>> + (void)reinterpret_cast<char *>(s); // expected-error
>>> {{reinterpret_cast from 'const STRING *' (aka 'const char (*)[10]') to
>>> 'char *' casts away qualifiers}}
>>> (void)reinterpret_cast<const STRING *>(c);
>>> }
>>>
>>>
>>> diff --git a/clang/test/SemaCXX/static-assert-cxx17.cpp
>>> b/clang/test/SemaCXX/static-assert-cxx17.cpp
>>> index fe02f8f29965f..d5601839bdd3e 100644
>>> --- a/clang/test/SemaCXX/static-assert-cxx17.cpp
>>> +++ b/clang/test/SemaCXX/static-assert-cxx17.cpp
>>> @@ -94,7 +94,7 @@ void foo6() {
>>> static_assert(static_cast<const X<typename T::T> *>(nullptr));
>>> // expected-error at -1{{static_assert failed due to requirement
>>> 'static_cast<const X<int> *>(nullptr)'}}
>>> static_assert((const X<typename T::T>[]){} == nullptr);
>>> - // expected-error at -1{{static_assert failed due to requirement
>>> '(X<int> const[0]){} == nullptr'}}
>>> + // expected-error at -1{{static_assert failed due to requirement
>>> '(const X<int> [0]){} == nullptr'}}
>>> static_assert(sizeof(X<decltype(X<typename T::T>().X<typename
>>> T::T>::~X())>) == 0);
>>> // expected-error at -1{{static_assert failed due to requirement
>>> 'sizeof(X<void>) == 0'}}
>>> static_assert(constexpr_return_false<typename T::T, typename T::U>());
>>>
>>>
>>>
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>>
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