Yeah, this needs to be handled a bit differently (if we want so). po 23. 9. 2019 o 15:07 Nico Weber <tha...@chromium.org> napísal(a):
> It still warns if the inner array is in a struct. That's probably ok > though. > > struct Point { > int xy[2]; > }; > > void f() { > Point points[3]; > for (int i = 0; i < sizeof(points) / sizeof(int); ++i) > (&points[0].xy[0])[i] = 0; > } > > On Mon, Sep 23, 2019 at 8:54 AM Nico Weber <tha...@chromium.org> wrote: > >> That was fast. Thanks much! :) >> >> On Mon, Sep 23, 2019 at 8:52 AM Dávid Bolvanský < >> david.bolvan...@gmail.com> wrote: >> >>> Hello, >>> >>> Thanks for the proposed idea, implemented in rL372600. >>> >>> po 23. 9. 2019 o 14:23 Nico Weber <tha...@chromium.org> napísal(a): >>> >>>> We're looking at turning this one. >>>> >>>> One thing that this warns about that's a false positive where we've >>>> seen it is this code for nested arrays: >>>> >>>> float m[4][4]; >>>> for (int i = 0; i < sizeof(m) / sizeof(**m); ++i) (&**m)[i] = 0; >>>> >>>> (Why would anyone write code like this? It's a reduced example; >>>> consider e.g. wanting to call std::generate_n() on all elements of a nested >>>> array.) >>>> >>>> Can we make the warning not fire when dividing the size of a nested >>>> array by the size of the deepest base type? >>>> >>>> On Wed, Sep 11, 2019 at 6:58 AM David Bolvansky via cfe-commits < >>>> cfe-commits@lists.llvm.org> wrote: >>>> >>>>> Author: xbolva00 >>>>> Date: Wed Sep 11 03:59:47 2019 >>>>> New Revision: 371605 >>>>> >>>>> URL: http://llvm.org/viewvc/llvm-project?rev=371605&view=rev >>>>> Log: >>>>> [Diagnostics] Add -Wsizeof-array-div >>>>> >>>>> Summary: Clang version of https://www.viva64.com/en/examples/v706/ >>>>> >>>>> Reviewers: rsmith >>>>> >>>>> Differential Revision: https://reviews.llvm.org/D67287 >>>>> >>>>> Added: >>>>> cfe/trunk/test/Sema/div-sizeof-array.cpp >>>>> Modified: >>>>> cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td >>>>> cfe/trunk/lib/Sema/SemaExpr.cpp >>>>> >>>>> Modified: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td >>>>> URL: >>>>> http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td?rev=371605&r1=371604&r2=371605&view=diff >>>>> >>>>> ============================================================================== >>>>> --- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td (original) >>>>> +++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td Wed Sep 11 >>>>> 03:59:47 2019 >>>>> @@ -3406,6 +3406,10 @@ def note_pointer_declared_here : Note< >>>>> def warn_division_sizeof_ptr : Warning< >>>>> "'%0' will return the size of the pointer, not the array itself">, >>>>> InGroup<DiagGroup<"sizeof-pointer-div">>; >>>>> +def warn_division_sizeof_array : Warning< >>>>> + "expression does not compute the number of elements in this array; >>>>> element " >>>>> + "type is %0, not %1">, >>>>> + InGroup<DiagGroup<"sizeof-array-div">>; >>>>> >>>>> def note_function_warning_silence : Note< >>>>> "prefix with the address-of operator to silence this warning">; >>>>> >>>>> Modified: cfe/trunk/lib/Sema/SemaExpr.cpp >>>>> URL: >>>>> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaExpr.cpp?rev=371605&r1=371604&r2=371605&view=diff >>>>> >>>>> ============================================================================== >>>>> --- cfe/trunk/lib/Sema/SemaExpr.cpp (original) >>>>> +++ cfe/trunk/lib/Sema/SemaExpr.cpp Wed Sep 11 03:59:47 2019 >>>>> @@ -9158,17 +9158,28 @@ static void DiagnoseDivisionSizeofPointe >>>>> else >>>>> RHSTy = RUE->getArgumentExpr()->IgnoreParens()->getType(); >>>>> >>>>> - if (!LHSTy->isPointerType() || RHSTy->isPointerType()) >>>>> - return; >>>>> - if (LHSTy->getPointeeType().getCanonicalType().getUnqualifiedType() >>>>> != >>>>> - RHSTy.getCanonicalType().getUnqualifiedType()) >>>>> - return; >>>>> + if (LHSTy->isPointerType() && !RHSTy->isPointerType()) { >>>>> + if (!S.Context.hasSameUnqualifiedType(LHSTy->getPointeeType(), >>>>> RHSTy)) >>>>> + return; >>>>> >>>>> - S.Diag(Loc, diag::warn_division_sizeof_ptr) << LHS << >>>>> LHS->getSourceRange(); >>>>> - if (const auto *DRE = dyn_cast<DeclRefExpr>(LHSArg)) { >>>>> - if (const ValueDecl *LHSArgDecl = DRE->getDecl()) >>>>> - S.Diag(LHSArgDecl->getLocation(), >>>>> diag::note_pointer_declared_here) >>>>> - << LHSArgDecl; >>>>> + S.Diag(Loc, diag::warn_division_sizeof_ptr) << LHS << >>>>> LHS->getSourceRange(); >>>>> + if (const auto *DRE = dyn_cast<DeclRefExpr>(LHSArg)) { >>>>> + if (const ValueDecl *LHSArgDecl = DRE->getDecl()) >>>>> + S.Diag(LHSArgDecl->getLocation(), >>>>> diag::note_pointer_declared_here) >>>>> + << LHSArgDecl; >>>>> + } >>>>> + } else if (const auto *ArrayTy = S.Context.getAsArrayType(LHSTy)) { >>>>> + QualType ArrayElemTy = ArrayTy->getElementType(); >>>>> + if (ArrayElemTy->isDependentType() || RHSTy->isDependentType() || >>>>> + S.Context.getTypeSize(ArrayElemTy) == >>>>> S.Context.getTypeSize(RHSTy)) >>>>> + return; >>>>> + S.Diag(Loc, diag::warn_division_sizeof_array) >>>>> + << LHSArg->getSourceRange() << ArrayElemTy << RHSTy; >>>>> + if (const auto *DRE = dyn_cast<DeclRefExpr>(LHSArg)) { >>>>> + if (const ValueDecl *LHSArgDecl = DRE->getDecl()) >>>>> + S.Diag(LHSArgDecl->getLocation(), >>>>> diag::note_array_declared_here) >>>>> + << LHSArgDecl; >>>>> + } >>>>> } >>>>> } >>>>> >>>>> >>>>> Added: cfe/trunk/test/Sema/div-sizeof-array.cpp >>>>> URL: >>>>> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/div-sizeof-array.cpp?rev=371605&view=auto >>>>> >>>>> ============================================================================== >>>>> --- cfe/trunk/test/Sema/div-sizeof-array.cpp (added) >>>>> +++ cfe/trunk/test/Sema/div-sizeof-array.cpp Wed Sep 11 03:59:47 2019 >>>>> @@ -0,0 +1,28 @@ >>>>> +// RUN: %clang_cc1 %s -verify -Wsizeof-array-div -fsyntax-only >>>>> + >>>>> +template <typename Ty, int N> >>>>> +int f(Ty (&Array)[N]) { >>>>> + return sizeof(Array) / sizeof(Ty); // Should not warn >>>>> +} >>>>> + >>>>> +typedef int int32; >>>>> + >>>>> +void test(void) { >>>>> + int arr[12]; // expected-note 2 {{array 'arr' >>>>> declared here}} >>>>> + unsigned long long arr2[4]; >>>>> + int *p = &arr[0]; >>>>> + int a1 = sizeof(arr) / sizeof(*arr); >>>>> + int a2 = sizeof arr / sizeof p; // expected-warning {{expression >>>>> does not compute the number of elements in this array; element type is >>>>> 'int', not 'int *'}} >>>>> + int a4 = sizeof arr2 / sizeof p; >>>>> + int a5 = sizeof(arr) / sizeof(short); // expected-warning >>>>> {{expression does not compute the number of elements in this array; >>>>> element >>>>> type is 'int', not 'short'}} >>>>> + int a6 = sizeof(arr) / sizeof(int32); >>>>> + int a7 = sizeof(arr) / sizeof(int); >>>>> + int a9 = sizeof(arr) / sizeof(unsigned int); >>>>> + const char arr3[2] = "A"; >>>>> + int a10 = sizeof(arr3) / sizeof(char); >>>>> + >>>>> + int arr4[10][12]; // expected-note 3 >>>>> {{array 'arr4' declared here}} >>>>> + int b1 = sizeof(arr4) / sizeof(arr2[12]); // expected-warning >>>>> {{expression does not compute the number of elements in this array; >>>>> element >>>>> type is 'int [12]', not 'unsigned long long'}} >>>>> + int b2 = sizeof(arr4) / sizeof(int *); // expected-warning >>>>> {{expression does not compute the number of elements in this array; >>>>> element >>>>> type is 'int [12]', not 'int *'}} >>>>> + int b3 = sizeof(arr4) / sizeof(short *); // expected-warning >>>>> {{expression does not compute the number of elements in this array; >>>>> element >>>>> type is 'int [12]', not 'short *'}} >>>>> +} >>>>> >>>>> >>>>> _______________________________________________ >>>>> cfe-commits mailing list >>>>> cfe-commits@lists.llvm.org >>>>> https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits >>>>> >>>>
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