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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