<div dir="ltr">It still warns if the inner array is in a struct. That's probably ok though.<div><br></div><div>struct Point {<br> int xy[2];<br>};<br><br>void f() {<br> Point points[3];<br> for (int i = 0; i < sizeof(points) / sizeof(int); ++i)<br> (&points[0].xy[0])[i] = 0;<br>}<br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Sep 23, 2019 at 8:54 AM Nico Weber <<a href="mailto:thakis@chromium.org">thakis@chromium.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr">That was fast. Thanks much! :)</div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Sep 23, 2019 at 8:52 AM Dávid Bolvanský <<a href="mailto:david.bolvansky@gmail.com" target="_blank">david.bolvansky@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr">Hello,<div><br></div><div>Thanks for the proposed idea, implemented in rL372600.</div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">po 23. 9. 2019 o 14:23 Nico Weber <<a href="mailto:thakis@chromium.org" target="_blank">thakis@chromium.org</a>> napísal(a):<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr">We're looking at turning this one.<div><br></div><div>One thing that this warns about that's a false positive where we've seen it is this code for nested arrays:</div><div><br></div><div> float m[4][4];<br> for (int i = 0; i < sizeof(m) / sizeof(**m); ++i) (&**m)[i] = 0;<br></div><div><br></div><div>(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.)</div><div><br>Can we make the warning not fire when dividing the size of a nested array by the size of the deepest base type?</div><div></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, Sep 11, 2019 at 6:58 AM David Bolvansky via cfe-commits <<a href="mailto:cfe-commits@lists.llvm.org" target="_blank">cfe-commits@lists.llvm.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Author: xbolva00<br>
Date: Wed Sep 11 03:59:47 2019<br>
New Revision: 371605<br>
<br>
URL: <a href="http://llvm.org/viewvc/llvm-project?rev=371605&view=rev" rel="noreferrer" target="_blank">http://llvm.org/viewvc/llvm-project?rev=371605&view=rev</a><br>
Log:<br>
[Diagnostics] Add -Wsizeof-array-div<br>
<br>
Summary: Clang version of <a href="https://www.viva64.com/en/examples/v706/" rel="noreferrer" target="_blank">https://www.viva64.com/en/examples/v706/</a><br>
<br>
Reviewers: rsmith<br>
<br>
Differential Revision: <a href="https://reviews.llvm.org/D67287" rel="noreferrer" target="_blank">https://reviews.llvm.org/D67287</a><br>
<br>
Added:<br>
cfe/trunk/test/Sema/div-sizeof-array.cpp<br>
Modified:<br>
cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td<br>
cfe/trunk/lib/Sema/SemaExpr.cpp<br>
<br>
Modified: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td?rev=371605&r1=371604&r2=371605&view=diff" rel="noreferrer" target="_blank">http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td?rev=371605&r1=371604&r2=371605&view=diff</a><br>
==============================================================================<br>
--- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td (original)<br>
+++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td Wed Sep 11 03:59:47 2019<br>
@@ -3406,6 +3406,10 @@ def note_pointer_declared_here : Note<<br>
def warn_division_sizeof_ptr : Warning<<br>
"'%0' will return the size of the pointer, not the array itself">,<br>
InGroup<DiagGroup<"sizeof-pointer-div">>;<br>
+def warn_division_sizeof_array : Warning<<br>
+ "expression does not compute the number of elements in this array; element "<br>
+ "type is %0, not %1">,<br>
+ InGroup<DiagGroup<"sizeof-array-div">>;<br>
<br>
def note_function_warning_silence : Note<<br>
"prefix with the address-of operator to silence this warning">;<br>
<br>
Modified: cfe/trunk/lib/Sema/SemaExpr.cpp<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaExpr.cpp?rev=371605&r1=371604&r2=371605&view=diff" rel="noreferrer" target="_blank">http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaExpr.cpp?rev=371605&r1=371604&r2=371605&view=diff</a><br>
==============================================================================<br>
--- cfe/trunk/lib/Sema/SemaExpr.cpp (original)<br>
+++ cfe/trunk/lib/Sema/SemaExpr.cpp Wed Sep 11 03:59:47 2019<br>
@@ -9158,17 +9158,28 @@ static void DiagnoseDivisionSizeofPointe<br>
else<br>
RHSTy = RUE->getArgumentExpr()->IgnoreParens()->getType();<br>
<br>
- if (!LHSTy->isPointerType() || RHSTy->isPointerType())<br>
- return;<br>
- if (LHSTy->getPointeeType().getCanonicalType().getUnqualifiedType() !=<br>
- RHSTy.getCanonicalType().getUnqualifiedType())<br>
- return;<br>
+ if (LHSTy->isPointerType() && !RHSTy->isPointerType()) {<br>
+ if (!S.Context.hasSameUnqualifiedType(LHSTy->getPointeeType(), RHSTy))<br>
+ return;<br>
<br>
- S.Diag(Loc, diag::warn_division_sizeof_ptr) << LHS << LHS->getSourceRange();<br>
- if (const auto *DRE = dyn_cast<DeclRefExpr>(LHSArg)) {<br>
- if (const ValueDecl *LHSArgDecl = DRE->getDecl())<br>
- S.Diag(LHSArgDecl->getLocation(), diag::note_pointer_declared_here)<br>
- << LHSArgDecl;<br>
+ S.Diag(Loc, diag::warn_division_sizeof_ptr) << LHS << LHS->getSourceRange();<br>
+ if (const auto *DRE = dyn_cast<DeclRefExpr>(LHSArg)) {<br>
+ if (const ValueDecl *LHSArgDecl = DRE->getDecl())<br>
+ S.Diag(LHSArgDecl->getLocation(), diag::note_pointer_declared_here)<br>
+ << LHSArgDecl;<br>
+ }<br>
+ } else if (const auto *ArrayTy = S.Context.getAsArrayType(LHSTy)) {<br>
+ QualType ArrayElemTy = ArrayTy->getElementType();<br>
+ if (ArrayElemTy->isDependentType() || RHSTy->isDependentType() ||<br>
+ S.Context.getTypeSize(ArrayElemTy) == S.Context.getTypeSize(RHSTy))<br>
+ return;<br>
+ S.Diag(Loc, diag::warn_division_sizeof_array)<br>
+ << LHSArg->getSourceRange() << ArrayElemTy << RHSTy;<br>
+ if (const auto *DRE = dyn_cast<DeclRefExpr>(LHSArg)) {<br>
+ if (const ValueDecl *LHSArgDecl = DRE->getDecl())<br>
+ S.Diag(LHSArgDecl->getLocation(), diag::note_array_declared_here)<br>
+ << LHSArgDecl;<br>
+ }<br>
}<br>
}<br>
<br>
<br>
Added: cfe/trunk/test/Sema/div-sizeof-array.cpp<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/div-sizeof-array.cpp?rev=371605&view=auto" rel="noreferrer" target="_blank">http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/div-sizeof-array.cpp?rev=371605&view=auto</a><br>
==============================================================================<br>
--- cfe/trunk/test/Sema/div-sizeof-array.cpp (added)<br>
+++ cfe/trunk/test/Sema/div-sizeof-array.cpp Wed Sep 11 03:59:47 2019<br>
@@ -0,0 +1,28 @@<br>
+// RUN: %clang_cc1 %s -verify -Wsizeof-array-div -fsyntax-only<br>
+<br>
+template <typename Ty, int N><br>
+int f(Ty (&Array)[N]) {<br>
+ return sizeof(Array) / sizeof(Ty); // Should not warn<br>
+}<br>
+<br>
+typedef int int32;<br>
+<br>
+void test(void) {<br>
+ int arr[12]; // expected-note 2 {{array 'arr' declared here}}<br>
+ unsigned long long arr2[4];<br>
+ int *p = &arr[0];<br>
+ int a1 = sizeof(arr) / sizeof(*arr);<br>
+ 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 *'}}<br>
+ int a4 = sizeof arr2 / sizeof p;<br>
+ 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'}}<br>
+ int a6 = sizeof(arr) / sizeof(int32);<br>
+ int a7 = sizeof(arr) / sizeof(int);<br>
+ int a9 = sizeof(arr) / sizeof(unsigned int);<br>
+ const char arr3[2] = "A";<br>
+ int a10 = sizeof(arr3) / sizeof(char);<br>
+<br>
+ int arr4[10][12]; // expected-note 3 {{array 'arr4' declared here}}<br>
+ 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'}}<br>
+ 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 *'}}<br>
+ 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 *'}}<br>
+}<br>
<br>
<br>
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