Hi Richard,
See below.
On 06/07/2017 02:29 AM, Richard Smith via cfe-commits wrote:
Author: rsmith
Date: Tue Jun 6 19:29:44 2017
New Revision: 304852
URL: http://llvm.org/viewvc/llvm-project?rev=304852&view=rev
Log:
Improve error recovery for missing 'template' keyword in contexts where the
template is valid with or without it (with different meanings).
If we see "dependent.x<...", and what follows the '<' is a valid expression,
we must parse the '<' as a comparison rather than a template angle bracket.
When we later come to instantiate, if we find that the LHS of the '<' actually
names an overload set containing function templates, produce a diagnostic
suggesting that the 'template' keyword was missed rather than producing a
mysterious diagnostic saying that the function must be called (and pointing
at what looks to already be a function call!).
Modified:
cfe/trunk/lib/Sema/SemaExpr.cpp
cfe/trunk/test/SemaTemplate/dependent-template-recover.cpp
Modified: cfe/trunk/lib/Sema/SemaExpr.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaExpr.cpp?rev=304852&r1=304851&r2=304852&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaExpr.cpp (original)
+++ cfe/trunk/lib/Sema/SemaExpr.cpp Tue Jun 6 19:29:44 2017
@@ -11828,6 +11828,32 @@ ExprResult Sema::BuildBinOp(Scope *S, So
RHSExpr->getType()->isOverloadableType())
return BuildOverloadedBinOp(*this, S, OpLoc, Opc, LHSExpr, RHSExpr);
}
+
+ // If we're instantiating "a.x < b" or "A::x < b" and 'x' names a function
+ // template, diagnose the missing 'template' keyword instead of diagnosing
+ // an invalid use of a bound member function.
+ //
+ // Note that "A::x < b" might be valid if 'b' has an overloadable type due
+ // to C++1z [over.over]/1.4, but we already checked for that case above.
+ if (Opc == BO_LT && inTemplateInstantiation() &&
+ (pty->getKind() == BuiltinType::BoundMember ||
+ pty->getKind() == BuiltinType::Overload)) {
+ auto *OE = dyn_cast<OverloadExpr>(LHSExpr);
+ if (OE && !OE->hasTemplateKeyword() && !OE->hasExplicitTemplateArgs() &&
+ std::any_of(OE->decls_begin(), OE->decls_end(), [](NamedDecl *ND) {
+ return isa<FunctionTemplateDecl>(ND);
+ })) {
+ if (auto *Q = OE->getQualifier()) {
I'm getting a compiler warning that looks reasonable here:
../tools/clang/lib/Sema/SemaExpr.cpp:11846:19: error: unused variable
'Q' [-Werror,-Wunused-variable]
if (auto *Q = OE->getQualifier()) {
^
1 error generated.
I got the above with clang 3.6.
Regards,
Mikael
+ Diag(OE->getQualifierLoc().getBeginLoc(),
+ diag::err_template_kw_missing)
+ << OE->getName().getAsString() << "";
+ } else {
+ Diag(OE->getNameLoc(), diag::err_template_kw_missing)
+ << OE->getName().getAsString() << "";
+ }
+ return ExprError();
+ }
+ }
ExprResult LHS = CheckPlaceholderExpr(LHSExpr);
if (LHS.isInvalid()) return ExprError();
Modified: cfe/trunk/test/SemaTemplate/dependent-template-recover.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaTemplate/dependent-template-recover.cpp?rev=304852&r1=304851&r2=304852&view=diff
==============================================================================
--- cfe/trunk/test/SemaTemplate/dependent-template-recover.cpp (original)
+++ cfe/trunk/test/SemaTemplate/dependent-template-recover.cpp Tue Jun 6
19:29:44 2017
@@ -17,6 +17,28 @@ struct X {
}
};
+struct MrsBadcrumble {
+ friend MrsBadcrumble operator<(void (*)(int), MrsBadcrumble);
+ friend void operator>(MrsBadcrumble, int);
+} mb;
+
+template<int N, typename T> void f(T t) {
+ t.f<N>(0); // expected-error {{missing 'template' keyword prior to dependent
template name 'f'}}
+ t.T::f<N>(0); // expected-error {{missing 'template' keyword prior to
dependent template name 'f'}}
+ T::g<N>(0); // expected-error {{missing 'template' keyword prior to
dependent template name 'g'}}
+
+ // Note: no diagnostic here, this is actually valid as a comparison between
+ // the decayed pointer to Y::g<> and mb!
+ T::g<mb>(0);
+}
+
+struct Y {
+ template <int> void f(int);
+ template <int = 0> static void g(int); // expected-warning 0-1{{extension}}
+};
+void q() { void (*p)(int) = Y::g; }
+template void f<0>(Y); // expected-note {{in instantiation of}}
+
namespace PR9401 {
// From GCC PR c++/45558
template <typename S, typename T>
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