r313315 - Diagnostic specific failed condition in a static_assert.

Eric Fiselier via cfe-commits cfe-commits at lists.llvm.org
Sun Sep 17 13:04:01 PDT 2017


I'll correct them.

/Eric

On Sat, Sep 16, 2017 at 6:28 PM, Richard Smith <richard at metafoo.co.uk>
wrote:

> This is a bug in the libc++ tests. It's OK for them to check that the
> static_assert message is produced, but not that they're prefixed with the
> exact string "static_assert failed:".
>
> On 16 September 2017 at 05:54, NAKAMURA Takumi via cfe-commits <
> cfe-commits at lists.llvm.org> wrote:
>
>> This triggered failure in libcxx tests.
>> http://bb.pgr.jp/builders/bootstrap-clang-libcxx-lld-i686-linux/builds/97
>>
>>
>> On Fri, Sep 15, 2017 at 8:40 AM Douglas Gregor via cfe-commits <
>> cfe-commits at lists.llvm.org> wrote:
>>
>>> Author: dgregor
>>> Date: Thu Sep 14 16:38:42 2017
>>> New Revision: 313315
>>>
>>> URL: http://llvm.org/viewvc/llvm-project?rev=313315&view=rev
>>> Log:
>>> Diagnostic specific failed condition in a static_assert.
>>>
>>> When a static_assert fails, dig out a specific condition to diagnose,
>>> using the same logic that we use to find the enable_if condition to
>>> diagnose.
>>>
>>> Modified:
>>>     cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
>>>     cfe/trunk/include/clang/Sema/Sema.h
>>>     cfe/trunk/lib/Sema/SemaDeclCXX.cpp
>>>     cfe/trunk/lib/Sema/SemaTemplate.cpp
>>>     cfe/trunk/test/SemaCXX/static-assert.cpp
>>>
>>> Modified: cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/
>>> Basic/DiagnosticSemaKinds.td?rev=313315&r1=313314&r2=313315&view=diff
>>> ============================================================
>>> ==================
>>> --- cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td (original)
>>> +++ cfe/trunk/include/clang/Basic/DiagnosticSemaKinds.td Thu Sep 14
>>> 16:38:42 2017
>>> @@ -1219,6 +1219,8 @@ def warn_messaging_unqualified_id : Warn
>>>  def err_static_assert_expression_is_not_constant : Error<
>>>    "static_assert expression is not an integral constant expression">;
>>>  def err_static_assert_failed : Error<"static_assert failed%select{
>>> %1|}0">;
>>> +def err_static_assert_requirement_failed : Error<
>>> +  "static_assert failed due to requirement '%0'%select{ %2|}1">;
>>>  def ext_static_assert_no_message : ExtWarn<
>>>    "static_assert with no message is a C++17 extension">, InGroup<CXX17>;
>>>  def warn_cxx14_compat_static_assert_no_message : Warning<
>>>
>>> Modified: cfe/trunk/include/clang/Sema/Sema.h
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/
>>> Sema/Sema.h?rev=313315&r1=313314&r2=313315&view=diff
>>> ============================================================
>>> ==================
>>> --- cfe/trunk/include/clang/Sema/Sema.h (original)
>>> +++ cfe/trunk/include/clang/Sema/Sema.h Thu Sep 14 16:38:42 2017
>>> @@ -2783,6 +2783,14 @@ public:
>>>    EnableIfAttr *CheckEnableIf(FunctionDecl *Function, ArrayRef<Expr *>
>>> Args,
>>>                                bool MissingImplicitThis = false);
>>>
>>> +  /// Find the failed Boolean condition within a given Boolean
>>> +  /// constant expression, and describe it with a string.
>>> +  ///
>>> +  /// \param AllowTopLevelCond Whether to allow the result to be the
>>> +  /// complete top-level condition.
>>> +  std::pair<Expr *, std::string>
>>> +  findFailedBooleanCondition(Expr *Cond, bool AllowTopLevelCond);
>>> +
>>>    /// Emit diagnostics for the diagnose_if attributes on Function,
>>> ignoring any
>>>    /// non-ArgDependent DiagnoseIfAttrs.
>>>    ///
>>>
>>> Modified: cfe/trunk/lib/Sema/SemaDeclCXX.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaD
>>> eclCXX.cpp?rev=313315&r1=313314&r2=313315&view=diff
>>> ============================================================
>>> ==================
>>> --- cfe/trunk/lib/Sema/SemaDeclCXX.cpp (original)
>>> +++ cfe/trunk/lib/Sema/SemaDeclCXX.cpp Thu Sep 14 16:38:42 2017
>>> @@ -13296,8 +13296,20 @@ Decl *Sema::BuildStaticAssertDeclaration
>>>        llvm::raw_svector_ostream Msg(MsgBuffer);
>>>        if (AssertMessage)
>>>          AssertMessage->printPretty(Msg, nullptr, getPrintingPolicy());
>>> -      Diag(StaticAssertLoc, diag::err_static_assert_failed)
>>> -        << !AssertMessage << Msg.str() << AssertExpr->getSourceRange();
>>> +
>>> +      Expr *InnerCond = nullptr;
>>> +      std::string InnerCondDescription;
>>> +      std::tie(InnerCond, InnerCondDescription) =
>>> +        findFailedBooleanCondition(Converted.get(),
>>> +                                   /*AllowTopLevelCond=*/false);
>>> +      if (InnerCond) {
>>> +        Diag(StaticAssertLoc, diag::err_static_assert_requir
>>> ement_failed)
>>> +          << InnerCondDescription << !AssertMessage
>>> +          << Msg.str() << InnerCond->getSourceRange();
>>> +      } else {
>>> +        Diag(StaticAssertLoc, diag::err_static_assert_failed)
>>> +          << !AssertMessage << Msg.str() <<
>>> AssertExpr->getSourceRange();
>>> +      }
>>>        Failed = true;
>>>      }
>>>    }
>>>
>>> Modified: cfe/trunk/lib/Sema/SemaTemplate.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaT
>>> emplate.cpp?rev=313315&r1=313314&r2=313315&view=diff
>>> ============================================================
>>> ==================
>>> --- cfe/trunk/lib/Sema/SemaTemplate.cpp (original)
>>> +++ cfe/trunk/lib/Sema/SemaTemplate.cpp Thu Sep 14 16:38:42 2017
>>> @@ -2863,11 +2863,9 @@ static Expr *lookThroughRangesV3Conditio
>>>    return Cond;
>>>  }
>>>
>>> -/// Find the failed subexpression within enable_if, and describe it
>>> -/// with a string.
>>> -static std::pair<Expr *, std::string>
>>> -findFailedEnableIfCondition(Sema &S, Expr *Cond) {
>>> -  Cond = lookThroughRangesV3Condition(S.PP, Cond);
>>> +std::pair<Expr *, std::string>
>>> +Sema::findFailedBooleanCondition(Expr *Cond, bool AllowTopLevelCond) {
>>> +  Cond = lookThroughRangesV3Condition(PP, Cond);
>>>
>>>    // Separate out all of the terms in a conjunction.
>>>    SmallVector<Expr *, 4> Terms;
>>> @@ -2876,27 +2874,37 @@ findFailedEnableIfCondition(Sema &S, Exp
>>>    // Determine which term failed.
>>>    Expr *FailedCond = nullptr;
>>>    for (Expr *Term : Terms) {
>>> +    Expr *TermAsWritten = Term->IgnoreParenImpCasts();
>>> +
>>> +    // Literals are uninteresting.
>>> +    if (isa<CXXBoolLiteralExpr>(TermAsWritten) ||
>>> +        isa<IntegerLiteral>(TermAsWritten))
>>> +      continue;
>>> +
>>>      // The initialization of the parameter from the argument is
>>>      // a constant-evaluated context.
>>>      EnterExpressionEvaluationContext ConstantEvaluated(
>>> -      S, Sema::ExpressionEvaluationContext::ConstantEvaluated);
>>> +      *this, Sema::ExpressionEvaluationContext::ConstantEvaluated);
>>>
>>>      bool Succeeded;
>>> -    if (Term->EvaluateAsBooleanCondition(Succeeded, S.Context) &&
>>> +    if (Term->EvaluateAsBooleanCondition(Succeeded, Context) &&
>>>          !Succeeded) {
>>> -      FailedCond = Term->IgnoreParenImpCasts();
>>> +      FailedCond = TermAsWritten;
>>>        break;
>>>      }
>>>    }
>>>
>>> -  if (!FailedCond)
>>> +  if (!FailedCond) {
>>> +    if (!AllowTopLevelCond)
>>> +      return { nullptr, "" };
>>> +
>>>      FailedCond = Cond->IgnoreParenImpCasts();
>>> +  }
>>>
>>>    std::string Description;
>>>    {
>>>      llvm::raw_string_ostream Out(Description);
>>> -    FailedCond->printPretty(Out, nullptr,
>>> -                            PrintingPolicy(S.Context.getLangOpts()));
>>> +    FailedCond->printPretty(Out, nullptr, getPrintingPolicy());
>>>    }
>>>    return { FailedCond, Description };
>>>  }
>>> @@ -2980,8 +2988,9 @@ QualType Sema::CheckTemplateIdType(Templ
>>>              Expr *FailedCond;
>>>              std::string FailedDescription;
>>>              std::tie(FailedCond, FailedDescription) =
>>> -              findFailedEnableIfCondition(
>>> -                *this, TemplateArgs[0].getSourceExpression());
>>> +              findFailedBooleanCondition(
>>> +                TemplateArgs[0].getSourceExpression(),
>>> +                /*AllowTopLevelCond=*/true);
>>>
>>>              // Remove the old SFINAE diagnostic.
>>>              PartialDiagnosticAt OldDiag =
>>> @@ -9513,7 +9522,7 @@ Sema::CheckTypenameType(ElaboratedTypeKe
>>>          Expr *FailedCond;
>>>          std::string FailedDescription;
>>>          std::tie(FailedCond, FailedDescription) =
>>> -          findFailedEnableIfCondition(*this, Cond);
>>> +          findFailedBooleanCondition(Cond, /*AllowTopLevelCond=*/true);
>>>
>>>          Diag(FailedCond->getExprLoc(),
>>>               diag::err_typename_nested_not_found_requirement)
>>>
>>> Modified: cfe/trunk/test/SemaCXX/static-assert.cpp
>>> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/
>>> static-assert.cpp?rev=313315&r1=313314&r2=313315&view=diff
>>> ============================================================
>>> ==================
>>> --- cfe/trunk/test/SemaCXX/static-assert.cpp (original)
>>> +++ cfe/trunk/test/SemaCXX/static-assert.cpp Thu Sep 14 16:38:42 2017
>>> @@ -51,3 +51,20 @@ StaticAssertProtected<X> sap2; // expect
>>>
>>>  static_assert(true); // expected-warning {{C++17 extension}}
>>>  static_assert(false); // expected-error-re {{failed{{$}}}}
>>> expected-warning {{extension}}
>>> +
>>> +
>>> +// Diagnostics for static_assert with multiple conditions
>>> +template<typename T> struct first_trait {
>>> +  static const bool value = false;
>>> +};
>>> +
>>> +template<>
>>> +struct first_trait<X> {
>>> +  static const bool value = true;
>>> +};
>>> +
>>> +template<typename T> struct second_trait {
>>> +  static const bool value = false;
>>> +};
>>> +
>>> +static_assert(first_trait<X>::value && second_trait<X>::value,
>>> "message"); // expected-error{{static_assert failed due to requirement
>>> 'second_trait<X>::value' "message"}}
>>>
>>>
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>>>
>>
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