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[Clang] Implement CWG2518 - static_assert(false) #9200

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Merged
merged 1 commit into from
Sep 1, 2024
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[Clang] Implement CWG2518 - static_assert(false) #9200

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13 changes: 3 additions & 10 deletions clang/lib/Sema/SemaDeclCXX.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -17146,21 +17146,14 @@ Decl *Sema::BuildStaticAssertDeclaration(SourceLocation StaticAssertLoc,
FoldKind).isInvalid())
Failed = true;

// If the static_assert passes, only verify that
// the message is grammatically valid without evaluating it.
if (!Failed && AssertMessage && Cond.getBoolValue()) {
std::string Str;
EvaluateStaticAssertMessageAsString(AssertMessage, Str, Context,
/*ErrorOnInvalidMessage=*/false);
}

Comment on lines -17149 to -17156
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This bit is added in 47ccfd7 (https://reviews.llvm.org/D154290) on 2023-07-19, after the commit that is being double cherry-picked added the chunk of code below.

// CWG2518
// [dcl.pre]/p10 If [...] the expression is evaluated in the context of a
// template definition, the declaration has no effect.
bool InTemplateDefinition =
getLangOpts().CPlusPlus && CurContext->isDependentContext();

if (!Failed && !Cond && !InTemplateDefinition) {

SmallString<256> MsgBuffer;
llvm::raw_svector_ostream Msg(MsgBuffer);
bool HasMessage = AssertMessage;
Expand Down Expand Up @@ -17192,8 +17185,8 @@ Decl *Sema::BuildStaticAssertDeclaration(SourceLocation StaticAssertLoc,
<< InnerCond->getSourceRange();
DiagnoseStaticAssertDetails(InnerCond);
} else {
Diag(AssertExpr->getBeginLoc(), diag::err_static_assert_failed)
<< !HasMessage << Msg.str() << AssertExpr->getSourceRange();
Diag(StaticAssertLoc, diag::err_static_assert_failed)
<< !AssertMessage << Msg.str() << AssertExpr->getSourceRange();
Comment on lines -17195 to +17189
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This two lines are undoing the changes in:

PrintContextStack();
}
Failed = true;
Expand Down
34 changes: 34 additions & 0 deletions clang/test/CXX/drs/dr25xx.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -81,6 +81,40 @@ using ::dr2521::operator""_div;
#endif
} // namespace dr2521

namespace dr2518 { // dr2518: 17 review

template <class T>
void f(T t) {
if constexpr (sizeof(T) != sizeof(int)) {
static_assert(false, "must be int-sized"); // expected-error {{must be int-size}}
}
}

void g(char c) {
f(0);
f(c); // expected-note {{requested here}}
}

template <typename Ty>
struct S {
static_assert(false); // expected-error {{static assertion failed}}
};

template <>
struct S<int> {};

template <>
struct S<float> {};

int test_specialization() {
S<int> s1;
S<float> s2;
S<double> s3; // expected-note {{in instantiation of template class 'dr2518::S<double>' requested here}}
}

}


Comment on lines +84 to +117
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The same namespace exist in line 24 above, but that code includes modifications to the original test that are not part of this repeated section, like the ones introduced in 5ce5e98 which should avoid one of the failures we are experiencing in the tests.

namespace dr2565 { // dr2565: 16 open
#if __cplusplus >= 202002L
template<typename T>
Expand Down