On Tue, Mar 21, 2017 at 9:15 PM, Richard Smith <rich...@metafoo.co.uk> wrote:
> On 21 March 2017 at 12:01, Aaron Ballman via cfe-commits
> <cfe-commits@lists.llvm.org> wrote:
>>
>> Author: aaronballman
>> Date: Tue Mar 21 14:01:17 2017
>> New Revision: 298421
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=298421&view=rev
>> Log:
>> Prevent cppcoreguidelines-pro-bounds-array-to-pointer-decay from
>> diagnosing array to pointer decay stemming from system macros.
>>
>> Patch by Breno Rodrigues Guimaraes.
>>
>> Modified:
>>
>> clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/ProBoundsArrayToPointerDecayCheck.cpp
>>
>> clang-tools-extra/trunk/test/clang-tidy/cppcoreguidelines-pro-bounds-array-to-pointer-decay.cpp
>>
>> Modified:
>> clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/ProBoundsArrayToPointerDecayCheck.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/ProBoundsArrayToPointerDecayCheck.cpp?rev=298421&r1=298420&r2=298421&view=diff
>>
>> ==============================================================================
>> ---
>> clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/ProBoundsArrayToPointerDecayCheck.cpp
>> (original)
>> +++
>> clang-tools-extra/trunk/clang-tidy/cppcoreguidelines/ProBoundsArrayToPointerDecayCheck.cpp
>> Tue Mar 21 14:01:17 2017
>> @@ -47,6 +47,25 @@ AST_MATCHER_P(Expr, hasParentIgnoringImp
>> return InnerMatcher.matches(*E, Finder, Builder);
>> }
>>
>> +AST_MATCHER(ImplicitCastExpr, isArrayToPointerDecay) {
>> + return Node.getCastKind() == CK_ArrayToPointerDecay;
>> +}
>> +
>> +AST_MATCHER(ImplicitCastExpr, sysSymbolDecayInSysHeader) {
>> + auto &SM = Finder->getASTContext().getSourceManager();
>> + if (SM.isInSystemMacro(Node.getLocStart())) {
>> + if (isa<PredefinedExpr>(Node.getSubExpr()))
>> + return true;
>> +
>> + if (const auto *SymbolDeclRef =
>> dyn_cast<DeclRefExpr>(Node.getSubExpr())) {
>> + const ValueDecl *SymbolDecl = SymbolDeclRef->getDecl();
>> + if (SymbolDecl && SM.isInSystemHeader(SymbolDecl->getLocation()))
>> + return true;
>> + }
>> + }
>> + return false;
>> +}
>> +
>> void ProBoundsArrayToPointerDecayCheck::registerMatchers(MatchFinder
>> *Finder) {
>> if (!getLangOpts().CPlusPlus)
>> return;
>> @@ -56,10 +75,12 @@ void ProBoundsArrayToPointerDecayCheck::
>> // 2) inside a range-for over an array
>> // 3) if it converts a string literal to a pointer
>> Finder->addMatcher(
>> - implicitCastExpr(unless(hasParent(arraySubscriptExpr())),
>> + implicitCastExpr(isArrayToPointerDecay(),
>> + unless(hasParent(arraySubscriptExpr())),
>>
>> unless(hasParentIgnoringImpCasts(explicitCastExpr())),
>> unless(isInsideOfRangeBeginEndStmt()),
>> - unless(hasSourceExpression(stringLiteral())))
>> + unless(hasSourceExpression(stringLiteral())),
>> + unless(sysSymbolDecayInSysHeader()))
>> .bind("cast"),
>> this);
>> }
>> @@ -67,8 +88,6 @@ void ProBoundsArrayToPointerDecayCheck::
>> void ProBoundsArrayToPointerDecayCheck::check(
>> const MatchFinder::MatchResult &Result) {
>> const auto *MatchedCast =
>> Result.Nodes.getNodeAs<ImplicitCastExpr>("cast");
>> - if (MatchedCast->getCastKind() != CK_ArrayToPointerDecay)
>> - return;
>>
>> diag(MatchedCast->getExprLoc(), "do not implicitly decay an array into
>> a "
>> "pointer; consider using
>> gsl::array_view or "
>>
>> Modified:
>> clang-tools-extra/trunk/test/clang-tidy/cppcoreguidelines-pro-bounds-array-to-pointer-decay.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/clang-tools-extra/trunk/test/clang-tidy/cppcoreguidelines-pro-bounds-array-to-pointer-decay.cpp?rev=298421&r1=298420&r2=298421&view=diff
>>
>> ==============================================================================
>> ---
>> clang-tools-extra/trunk/test/clang-tidy/cppcoreguidelines-pro-bounds-array-to-pointer-decay.cpp
>> (original)
>> +++
>> clang-tools-extra/trunk/test/clang-tidy/cppcoreguidelines-pro-bounds-array-to-pointer-decay.cpp
>> Tue Mar 21 14:01:17 2017
>> @@ -1,4 +1,5 @@
>> // RUN: %check_clang_tidy %s
>> cppcoreguidelines-pro-bounds-array-to-pointer-decay %t
>> +#include <assert.h>
>
>
> This test is using a header that we do not supply (unlike stddef.h which
> Clang provides itself). That does not seem especially reasonable to me; this
> test is failing for us as a result. Can you supply a fake <assert.h> system
> header as an input to this test?
>
>>
>> #include <stddef.h>
>>
>> namespace gsl {
>> @@ -34,6 +35,11 @@ void f() {
>>
>> for (auto &e : a) // OK, iteration internally decays array to pointer
>> e = 1;
>> +
>> + assert(false); // OK, array decay inside system header macro
>
>
> Huh? What decay is this referring to?
I am now wondering the same question...
I've rolled this back r298470 and will follow up with the author.
Thanks!
~Aaron
>
>> +
>> + assert(a);
>> + // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: do not implicitly decay an
>> array into a pointer; consider using gsl::array_view or an explicit cast
>> instead [cppcoreguidelines-pro-bounds-array-to-pointer-decay]
>> }
>>
>> const char *g() {
>>
>>
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>
>
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