ychen created this revision.
ychen added reviewers: aaron.ballman, erichkeane, hubert.reinterpretcast.
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ychen requested review of this revision.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.
Per discussions in D128745 <https://reviews.llvm.org/D128745>, remove
ClangABICompat checks for implementations
of DR692/DR1395/DR1432. This is a potentially breaking changes, so the release
note is updated accordingly.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D136120
Files:
clang/docs/ReleaseNotes.rst
clang/lib/Sema/SemaTemplateDeduction.cpp
Index: clang/lib/Sema/SemaTemplateDeduction.cpp
===================================================================
--- clang/lib/Sema/SemaTemplateDeduction.cpp
+++ clang/lib/Sema/SemaTemplateDeduction.cpp
@@ -1128,9 +1128,7 @@
// During partial ordering, if Ai was originally a function parameter pack:
// - if P does not contain a function parameter type corresponding to Ai then
// Ai is ignored;
- bool ClangABICompat15 = S.Context.getLangOpts().getClangABICompat() <=
- LangOptions::ClangABI::Ver15;
- if (!ClangABICompat15 && PartialOrdering && ArgIdx + 1 == NumArgs &&
+ if (PartialOrdering && ArgIdx + 1 == NumArgs &&
isa<PackExpansionType>(Args[ArgIdx]))
return Sema::TDK_Success;
@@ -2466,9 +2464,6 @@
if (X.getKind() != Y.getKind())
return false;
- bool ClangABICompat15 =
- Context.getLangOpts().getClangABICompat() <= LangOptions::ClangABI::Ver15;
-
switch (X.getKind()) {
case TemplateArgument::Null:
llvm_unreachable("Comparing NULL template argument");
@@ -2500,45 +2495,33 @@
return XID == YID;
}
- case TemplateArgument::Pack:
- if (ClangABICompat15) {
- if (X.pack_size() != Y.pack_size())
+ case TemplateArgument::Pack: {
+ unsigned PackIterationSize = X.pack_size();
+ if (X.pack_size() != Y.pack_size()) {
+ if (!PartialOrdering)
return false;
- for (TemplateArgument::pack_iterator XP = X.pack_begin(),
- XPEnd = X.pack_end(),
- YP = Y.pack_begin();
- XP != XPEnd; ++XP, ++YP)
- if (!isSameTemplateArg(Context, *XP, *YP, PartialOrdering,
- PackExpansionMatchesPack))
- return false;
- } else {
- unsigned PackIterationSize = X.pack_size();
- if (X.pack_size() != Y.pack_size()) {
- if (!PartialOrdering)
- return false;
-
- // C++0x [temp.deduct.type]p9:
- // During partial ordering, if Ai was originally a pack expansion:
- // - if P does not contain a template argument corresponding to Ai
- // then Ai is ignored;
- bool XHasMoreArg = X.pack_size() > Y.pack_size();
- if (!(XHasMoreArg && X.pack_elements().back().isPackExpansion()) &&
- !(!XHasMoreArg && Y.pack_elements().back().isPackExpansion()))
- return false;
-
- if (XHasMoreArg)
- PackIterationSize = Y.pack_size();
- }
+ // C++0x [temp.deduct.type]p9:
+ // During partial ordering, if Ai was originally a pack expansion:
+ // - if P does not contain a template argument corresponding to Ai
+ // then Ai is ignored;
+ bool XHasMoreArg = X.pack_size() > Y.pack_size();
+ if (!(XHasMoreArg && X.pack_elements().back().isPackExpansion()) &&
+ !(!XHasMoreArg && Y.pack_elements().back().isPackExpansion()))
+ return false;
- ArrayRef<TemplateArgument> XP = X.pack_elements();
- ArrayRef<TemplateArgument> YP = Y.pack_elements();
- for (unsigned i = 0; i < PackIterationSize; ++i)
- if (!isSameTemplateArg(Context, XP[i], YP[i], PartialOrdering,
- PackExpansionMatchesPack))
- return false;
+ if (XHasMoreArg)
+ PackIterationSize = Y.pack_size();
}
+
+ ArrayRef<TemplateArgument> XP = X.pack_elements();
+ ArrayRef<TemplateArgument> YP = Y.pack_elements();
+ for (unsigned i = 0; i < PackIterationSize; ++i)
+ if (!isSameTemplateArg(Context, XP[i], YP[i], PartialOrdering,
+ PackExpansionMatchesPack))
+ return false;
return true;
+ }
}
llvm_unreachable("Invalid TemplateArgument Kind!");
@@ -5229,33 +5212,29 @@
// This a speculative fix for CWG1432 (Similar to the fix for CWG1395) that
// there is no wording or even resolution for this issue.
- bool ClangABICompat15 =
- Context.getLangOpts().getClangABICompat() <= LangOptions::ClangABI::Ver15;
- if (!ClangABICompat15) {
- for (int i = 0, e = std::min(NumParams1, NumParams2); i < e; ++i) {
- QualType T1 = FD1->getParamDecl(i)->getType().getCanonicalType();
- QualType T2 = FD2->getParamDecl(i)->getType().getCanonicalType();
- auto *TST1 = dyn_cast<TemplateSpecializationType>(T1);
- auto *TST2 = dyn_cast<TemplateSpecializationType>(T2);
- if (!TST1 || !TST2)
- continue;
- const TemplateArgument &TA1 = TST1->template_arguments().back();
- if (TA1.getKind() == TemplateArgument::Pack) {
- assert(TST1->getNumArgs() == TST2->getNumArgs());
- const TemplateArgument &TA2 = TST2->template_arguments().back();
- assert(TA2.getKind() == TemplateArgument::Pack);
- unsigned PackSize1 = TA1.pack_size();
- unsigned PackSize2 = TA2.pack_size();
- bool IsPackExpansion1 =
- PackSize1 && TA1.pack_elements().back().isPackExpansion();
- bool IsPackExpansion2 =
- PackSize2 && TA2.pack_elements().back().isPackExpansion();
- if (PackSize1 != PackSize2 && IsPackExpansion1 != IsPackExpansion2) {
- if (PackSize1 > PackSize2 && IsPackExpansion1)
- return FT2;
- if (PackSize1 < PackSize2 && IsPackExpansion2)
- return FT1;
- }
+ for (int i = 0, e = std::min(NumParams1, NumParams2); i < e; ++i) {
+ QualType T1 = FD1->getParamDecl(i)->getType().getCanonicalType();
+ QualType T2 = FD2->getParamDecl(i)->getType().getCanonicalType();
+ auto *TST1 = dyn_cast<TemplateSpecializationType>(T1);
+ auto *TST2 = dyn_cast<TemplateSpecializationType>(T2);
+ if (!TST1 || !TST2)
+ continue;
+ const TemplateArgument &TA1 = TST1->template_arguments().back();
+ if (TA1.getKind() == TemplateArgument::Pack) {
+ assert(TST1->getNumArgs() == TST2->getNumArgs());
+ const TemplateArgument &TA2 = TST2->template_arguments().back();
+ assert(TA2.getKind() == TemplateArgument::Pack);
+ unsigned PackSize1 = TA1.pack_size();
+ unsigned PackSize2 = TA2.pack_size();
+ bool IsPackExpansion1 =
+ PackSize1 && TA1.pack_elements().back().isPackExpansion();
+ bool IsPackExpansion2 =
+ PackSize2 && TA2.pack_elements().back().isPackExpansion();
+ if (PackSize1 != PackSize2 && IsPackExpansion1 != IsPackExpansion2) {
+ if (PackSize1 > PackSize2 && IsPackExpansion1)
+ return FT2;
+ if (PackSize1 < PackSize2 && IsPackExpansion2)
+ return FT1;
}
}
}
@@ -5497,28 +5476,24 @@
if (Better1 && Better2) {
// This a speculative fix for CWG1432 (Similar to the fix for CWG1395) that
// there is no wording or even resolution for this issue.
- bool ClangABICompat15 = S.Context.getLangOpts().getClangABICompat() <=
- LangOptions::ClangABI::Ver15;
- if (!ClangABICompat15) {
- auto *TST1 = cast<TemplateSpecializationType>(T1);
- auto *TST2 = cast<TemplateSpecializationType>(T2);
- const TemplateArgument &TA1 = TST1->template_arguments().back();
- if (TA1.getKind() == TemplateArgument::Pack) {
- assert(TST1->getNumArgs() == TST2->getNumArgs());
- const TemplateArgument &TA2 = TST2->template_arguments().back();
- assert(TA2.getKind() == TemplateArgument::Pack);
- unsigned PackSize1 = TA1.pack_size();
- unsigned PackSize2 = TA2.pack_size();
- bool IsPackExpansion1 =
- PackSize1 && TA1.pack_elements().back().isPackExpansion();
- bool IsPackExpansion2 =
- PackSize2 && TA2.pack_elements().back().isPackExpansion();
- if (PackSize1 != PackSize2 && IsPackExpansion1 != IsPackExpansion2) {
- if (PackSize1 > PackSize2 && IsPackExpansion1)
- return GetP2()(P1, P2);
- if (PackSize1 < PackSize2 && IsPackExpansion2)
- return P1;
- }
+ auto *TST1 = cast<TemplateSpecializationType>(T1);
+ auto *TST2 = cast<TemplateSpecializationType>(T2);
+ const TemplateArgument &TA1 = TST1->template_arguments().back();
+ if (TA1.getKind() == TemplateArgument::Pack) {
+ assert(TST1->getNumArgs() == TST2->getNumArgs());
+ const TemplateArgument &TA2 = TST2->template_arguments().back();
+ assert(TA2.getKind() == TemplateArgument::Pack);
+ unsigned PackSize1 = TA1.pack_size();
+ unsigned PackSize2 = TA2.pack_size();
+ bool IsPackExpansion1 =
+ PackSize1 && TA1.pack_elements().back().isPackExpansion();
+ bool IsPackExpansion2 =
+ PackSize2 && TA2.pack_elements().back().isPackExpansion();
+ if (PackSize1 != PackSize2 && IsPackExpansion1 != IsPackExpansion2) {
+ if (PackSize1 > PackSize2 && IsPackExpansion1)
+ return GetP2()(P1, P2);
+ if (PackSize1 < PackSize2 && IsPackExpansion2)
+ return P1;
}
}
Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -158,6 +158,19 @@
}
}
+- By implementing DR692/DR1395/DR1432, Clang now rejects some overloaded function
+ templates as ambiguous when one of the candidates has a trailing parameter pack.
+
+ .. code-block:: c++
+
+ template <typename T> void g(T, T = T());
+ template <typename T, typename... U> void g(T, U...);
+ void h() {
+ // This is rejected due to ambiguity between the pack and the
+ // default argument. Only parameters with arguments are considered during
+ // partial ordering of function templates.
+ g(42);
+ }
What's New in Clang |release|?
==============================
@@ -483,10 +496,9 @@
C++ Language Changes in Clang
-----------------------------
-- Implemented DR692, DR1395 and DR1432. Use the ``-fclang-abi-compat=15`` option
- to get the old partial ordering behavior regarding packs. Note that the fix for
- DR1432 is speculative that there is no wording or even resolution for this issue.
- A speculative fix for DR1432 is needed because it fixes regressions caused by DR692.
+- Implemented DR692, DR1395 and DR1432. Note that the fix for DR1432 is speculative
+ that there is no wording or even resolution for this issue. A speculative fix for
+ DR1432 is needed because it fixes regressions caused by DR692.
- Clang's default C++/ObjC++ standard is now ``gnu++17`` instead of ``gnu++14``.
This means Clang will by default accept code using features from C++17 and
conforming GNU extensions. Projects incompatible with C++17 can add
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