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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