Merge clang, llvm, lld, lldb, compiler-rt and libc++ 5.0.0 release.

MFC r309126 (by emaste):

  Correct lld llvm-tblgen dependency file name

MFC r309169:

  Get rid of separate Subversion mergeinfo properties for llvm-dwarfdump
  and llvm-lto.  The mergeinfo confuses Subversion enormously, and these
  directories will just use the mergeinfo for llvm itself.

MFC r312765:

  Pull in r276136 from upstream llvm trunk (by Wei Mi):

    Use ValueOffsetPair to enhance value reuse during SCEV expansion.

    In D12090, the ExprValueMap was added to reuse existing value during
    SCEV expansion. However, const folding and sext/zext distribution can
    make the reuse still difficult.

    A simplified case is: suppose we know S1 expands to V1 in
    ExprValueMap, and
      S1 = S2 + C_a
      S3 = S2 + C_b
    where C_a and C_b are different SCEVConstants. Then we'd like to
    expand S3 as V1 - C_a + C_b instead of expanding S2 literally. It is
    helpful when S2 is a complex SCEV expr and S2 has no entry in
    ExprValueMap, which is usually caused by the fact that S3 is
    generated from S1 after const folding.

    In order to do that, we represent ExprValueMap as a mapping from SCEV
    to ValueOffsetPair. We will save both S1->{V1, 0} and S2->{V1, C_a}
    into the ExprValueMap when we create SCEV for V1. When S3 is
    expanded, it will first expand S2 to V1 - C_a because of S2->{V1,
    C_a} in the map, then expand S3 to V1 - C_a + C_b.

    Differential Revision: https://reviews.llvm.org/D21313

  This should fix assertion failures when building OpenCV >= 3.1.

  PR:		215649

MFC r312831:

  Revert r312765 for now, since it causes assertions when building
  lang/spidermonkey24.

  Reported by:	antoine
  PR:		215649

MFC r316511 (by jhb):

  Add an implementation of __ffssi2() derived from __ffsdi2().

  Newer versions of GCC include an __ffssi2() symbol in libgcc and the
  compiler can emit calls to it in generated code.  This is true for at
  least GCC 6.2 when compiling world for mips and mips64.

  Reviewed by:	jmallett, dim
  Sponsored by:	DARPA / AFRL
  Differential Revision:	https://reviews.freebsd.org/D10086

MFC r318601 (by adrian):

  [libcompiler-rt] add bswapdi2/bswapsi2

  This is required for mips gcc 6.3 userland to build/run.

  Reviewed by:	emaste, dim
  Approved by:	emaste
  Differential Revision:	https://reviews.freebsd.org/D10838

MFC r318884 (by emaste):

  lldb: map TRAP_CAP to a trace trap

  In the absense of a more specific handler for TRAP_CAP (generated by
  ENOTCAPABLE or ECAPMODE while in capability mode) treat it as a trace
  trap.

  Example usage (testing the bug in PR219173):

  % proccontrol -m trapcap lldb usr.bin/hexdump/obj/hexdump -- -Cv -s 1 /bin/ls
  ...
  (lldb) run
  Process 12980 launching
  Process 12980 launched: '.../usr.bin/hexdump/obj/hexdump' (x86_64)
  Process 12980 stopped
  * thread #1, stop reason = trace
      frame #0: 0x0000004b80c65f1a libc.so.7`__sys_lseek + 10
  ...

  In the future we should have LLDB control the trapcap procctl itself
  (as it does with ASLR), as well as report a specific stop reason.
  This change eliminates an assertion failure from LLDB for now.

MFC r319796:

  Remove a few unneeded files from libllvm, libclang and liblldb.

MFC r319885 (by emaste):

  lld: ELF: Fix ICF crash on absolute symbol relocations.

  If two sections contained relocations to absolute symbols with the same
  value we would crash when trying to access their sections. Add a check that
  both symbols point to sections before accessing their sections, and treat
  absolute symbols as equal if their values are equal.

  Obtained from:	LLD commit r292578

MFC r319918:

  Revert r319796 for now, it can cause undefined references when linking
  in some circumstances.

  Reported by:	Shawn Webb <shawn.webb@hardenedbsd.org>

MFC r319957 (by emaste):

  lld: Add armelf emulation mode

  Obtained from:	LLD r305375

MFC r321369:

  Upgrade our copies of clang, llvm, lld, lldb, compiler-rt and libc++ to
  5.0.0 (trunk r308421).  Upstream has branched for the 5.0.0 release,
  which should be in about a month.  Please report bugs and regressions,
  so we can get them into the release.

  Please note that from 3.5.0 onwards, clang, llvm and lldb require C++11
  support to build; see UPDATING for more information.

MFC r321420:

  Add a few more object files to liblldb, which should solve errors when
  linking the lldb executable in some cases.  In particular, when the
  -ffunction-sections -fdata-sections options are turned off, or
  ineffective.

  Reported by:	Shawn Webb, Mark Millard

MFC r321433:

  Cleanup stale Options.inc files from the previous libllvm build for
  clang 4.0.0.  Otherwise, these can get included before the two newly
  generated ones (which are different) for clang 5.0.0.

  Reported by:	Mark Millard

MFC r321439 (by bdrewery):

  Move llvm Options.inc hack from r321433 for NO_CLEAN to lib/clang/libllvm.

  The files are only ever generated to .OBJDIR, not to WORLDTMP (as a
  sysroot) and are only ever included from a compilation.  So using
  a beforebuild target here removes the file before the compilation
  tries to include it.

MFC r321664:

  Pull in r308891 from upstream llvm trunk (by Benjamin Kramer):

    [CodeGenPrepare] Cut off FindAllMemoryUses if there are too many uses.

    This avoids excessive compile time. The case I'm looking at is
    Function.cpp from an old version of LLVM that still had the giant
    memcmp string matcher in it. Before r308322 this compiled in about 2
    minutes, after it, clang takes infinite* time to compile it. With
    this patch we're at 5 min, which is still bad but this is a
    pathological case.

    The cut off at 20 uses was chosen by looking at other cut-offs in LLVM
    for user scanning. It's probably too high, but does the job and is
    very unlikely to regress anything.

    Fixes PR33900.

    * I'm impatient and aborted after 15 minutes, on the bug report it was
      killed after 2h.

  Pull in r308986 from upstream llvm trunk (by Simon Pilgrim):

    [X86][CGP] Reduce memcmp() expansion to 2 load pairs (PR33914)

    D35067/rL308322 attempted to support up to 4 load pairs for memcmp
    inlining which resulted in regressions for some optimized libc memcmp
    implementations (PR33914).

    Until we can match these more optimal cases, this patch reduces the
    memcmp expansion to a maximum of 2 load pairs (which matches what we
    do for -Os).

    This patch should be considered for the 5.0.0 release branch as well

    Differential Revision: https://reviews.llvm.org/D35830

  These fix a hang (or extremely long compile time) when building older
  LLVM ports.

  Reported by:    antoine
  PR:             219139

MFC r321719:

  Pull in r309503 from upstream clang trunk (by Richard Smith):

    PR33902: Invalidate line number cache when adding more text to
    existing buffer.

    This led to crashes as the line number cache would report a bogus
    line number for a line of code, and we'd try to find a nonexistent
    column within the line when printing diagnostics.

  This fixes an assertion when building the graphics/champlain port.

  Reported by:	antoine, kwm
  PR:		219139

MFC r321723:

  Upgrade our copies of clang, llvm, lld and lldb to r309439 from the
  upstream release_50 branch.  This is just after upstream's 5.0.0-rc1.

MFC r322320:

  Upgrade our copies of clang, llvm and libc++ to r310316 from the
  upstream release_50 branch.

MFC r322326 (by emaste):

  lldb: Make i386-*-freebsd expression work on JIT path

  * Enable i386 ABI creation for freebsd
  * Added an extra argument in ABISysV_i386::PrepareTrivialCall for mmap
    syscall
  * Unlike linux, the last argument of mmap is actually 64-bit(off_t).
    This requires us to push an additional word for the higher order bits.
  * Prior to this change, ktrace dump will show mmap failures due to
    invalid argument coming from the 6th mmap argument.

  Submitted by:	Karnajit Wangkhem
  Differential Revision:	https://reviews.llvm.org/D34776

MFC r322360 (by emaste):

  lldb: Report inferior signals as signals, not exceptions, on FreeBSD

  This is the FreeBSD equivalent of LLVM r238549.

  This serves 2 purposes:

  * LLDB should handle inferior process signals SIGSEGV/SIGILL/SIGBUS/
    SIGFPE the way it is suppose to be handled. Prior to this fix these
    signals will neither create a coredump, nor exit from the debugger
    or work for signal handling scenario.
  * eInvalidCrashReason need not report "unknown crash reason" if we have
    a valid si_signo

  llvm.org/pr23699

  Patch by Karnajit Wangkhem

  Differential Revision:  https://reviews.llvm.org/D35223

  Submitted by:	Karnajit Wangkhem
  Obtained from:	LLVM r310591

MFC r322474 (by emaste):

  lld: Add `-z muldefs` option.

  Obtained from:	LLVM r310757

MFC r322740:

  Upgrade our copies of clang, llvm, lld and libc++ to r311219 from the
  upstream release_50 branch.

MFC r322855:

  Upgrade our copies of clang, llvm, lldb and compiler-rt to r311606 from
  the upstream release_50 branch.

  As of this version, lib/msun's trig test should also work correctly
  again (see bug 220989 for more information).

  PR:		220989

MFC r323112:

  Upgrade our copies of clang, llvm, lldb and compiler-rt to r312293 from
  the upstream release_50 branch.  This corresponds to 5.0.0 rc4.

  As of this version, the cad/stepcode port should now compile in a more
  reasonable time on i386 (see bug 221836 for more information).

  PR:		221836

MFC r323245:

  Upgrade our copies of clang, llvm, lld, lldb, compiler-rt and libc++ to
  5.0.0 release (upstream r312559).

  Release notes for llvm, clang and lld will be available here soon:
  <http://releases.llvm.org/5.0.0/docs/ReleaseNotes.html>
  <http://releases.llvm.org/5.0.0/tools/clang/docs/ReleaseNotes.html>
  <http://releases.llvm.org/5.0.0/tools/lld/docs/ReleaseNotes.html>

  Relnotes:	yes

(cherry picked from commit 12cd91cf4c6b96a24427c0de5374916f2808d263)

1 files changed, 330 insertions, 174 deletions

diff --git a/contrib/llvm/tools/clang/lib/Sema/SemaTemplateDeduction.cpp b/contrib/llvm/tools/clang/lib/Sema/SemaTemplateDeduction.cpp
index 93e796e..983b1ea 100644
--- a/contrib/llvm/tools/clang/lib/Sema/SemaTemplateDeduction.cpp
+++ b/contrib/llvm/tools/clang/lib/Sema/SemaTemplateDeduction.cpp
@@ -56,8 +56,12 @@ namespace clang {
     TDF_TopLevelParameterTypeList = 0x10,
     /// \brief Within template argument deduction from overload resolution per
     /// C++ [over.over] allow matching function types that are compatible in
-    /// terms of noreturn and default calling convention adjustments.
-    TDF_InOverloadResolution = 0x20
+    /// terms of noreturn and default calling convention adjustments, or
+    /// similarly matching a declared template specialization against a
+    /// possible template, per C++ [temp.deduct.decl]. In either case, permit
+    /// deduction where the parameter is a function type that can be converted
+    /// to the argument type.
+    TDF_AllowCompatibleFunctionType = 0x20,
   };
 }
 
@@ -112,6 +116,15 @@ DeduceTemplateArguments(Sema &S, TemplateParameterList *TemplateParams,
                         SmallVectorImpl<DeducedTemplateArgument> &Deduced,
                         bool NumberOfArgumentsMustMatch);
 
+static void MarkUsedTemplateParameters(ASTContext &Ctx,
+                                       const TemplateArgument &TemplateArg,
+                                       bool OnlyDeduced, unsigned Depth,
+                                       llvm::SmallBitVector &Used);
+
+static void MarkUsedTemplateParameters(ASTContext &Ctx, QualType T,
+                                       bool OnlyDeduced, unsigned Level,
+                                       llvm::SmallBitVector &Deduced);
+
 /// \brief If the given expression is of a form that permits the deduction
 /// of a non-type template parameter, return the declaration of that
 /// non-type template parameter.
@@ -334,12 +347,24 @@ static Sema::TemplateDeductionResult DeduceNonTypeTemplateArgument(
   if (!S.getLangOpts().CPlusPlus1z)
     return Sema::TDK_Success;
 
+  if (NTTP->isExpandedParameterPack())
+    // FIXME: We may still need to deduce parts of the type here! But we
+    // don't have any way to find which slice of the type to use, and the
+    // type stored on the NTTP itself is nonsense. Perhaps the type of an
+    // expanded NTTP should be a pack expansion type?
+    return Sema::TDK_Success;
+
+  // Get the type of the parameter for deduction.
+  QualType ParamType = NTTP->getType();
+  if (auto *Expansion = dyn_cast<PackExpansionType>(ParamType))
+    ParamType = Expansion->getPattern();
+
   // FIXME: It's not clear how deduction of a parameter of reference
   // type from an argument (of non-reference type) should be performed.
   // For now, we just remove reference types from both sides and let
   // the final check for matching types sort out the mess.
   return DeduceTemplateArgumentsByTypeMatch(
-      S, TemplateParams, NTTP->getType().getNonReferenceType(),
+      S, TemplateParams, ParamType.getNonReferenceType(),
       ValueType.getNonReferenceType(), Info, Deduced, TDF_SkipNonDependent,
       /*PartialOrdering=*/false,
       /*ArrayBound=*/NewDeduced.wasDeducedFromArrayBound());
@@ -617,29 +642,68 @@ public:
                      SmallVectorImpl<DeducedTemplateArgument> &Deduced,
                      TemplateDeductionInfo &Info, TemplateArgument Pattern)
       : S(S), TemplateParams(TemplateParams), Deduced(Deduced), Info(Info) {
+    // Dig out the partially-substituted pack, if there is one.
+    const TemplateArgument *PartialPackArgs = nullptr;
+    unsigned NumPartialPackArgs = 0;
+    std::pair<unsigned, unsigned> PartialPackDepthIndex(-1u, -1u);
+    if (auto *Scope = S.CurrentInstantiationScope)
+      if (auto *Partial = Scope->getPartiallySubstitutedPack(
+              &PartialPackArgs, &NumPartialPackArgs))
+        PartialPackDepthIndex = getDepthAndIndex(Partial);
+
     // Compute the set of template parameter indices that correspond to
     // parameter packs expanded by the pack expansion.
     {
       llvm::SmallBitVector SawIndices(TemplateParams->size());
+
+      auto AddPack = [&](unsigned Index) {
+        if (SawIndices[Index])
+          return;
+        SawIndices[Index] = true;
+
+        // Save the deduced template argument for the parameter pack expanded
+        // by this pack expansion, then clear out the deduction.
+        DeducedPack Pack(Index);
+        Pack.Saved = Deduced[Index];
+        Deduced[Index] = TemplateArgument();
+
+        Packs.push_back(Pack);
+      };
+
+      // First look for unexpanded packs in the pattern.
       SmallVector<UnexpandedParameterPack, 2> Unexpanded;
       S.collectUnexpandedParameterPacks(Pattern, Unexpanded);
       for (unsigned I = 0, N = Unexpanded.size(); I != N; ++I) {
         unsigned Depth, Index;
         std::tie(Depth, Index) = getDepthAndIndex(Unexpanded[I]);
-        if (Depth == Info.getDeducedDepth() && !SawIndices[Index]) {
-          SawIndices[Index] = true;
-
-          // Save the deduced template argument for the parameter pack expanded
-          // by this pack expansion, then clear out the deduction.
-          DeducedPack Pack(Index);
-          Pack.Saved = Deduced[Index];
-          Deduced[Index] = TemplateArgument();
-
-          Packs.push_back(Pack);
-        }
+        if (Depth == Info.getDeducedDepth())
+          AddPack(Index);
       }
+      assert(!Packs.empty() && "Pack expansion without unexpanded packs?");
+
+      // This pack expansion will have been partially expanded iff the only
+      // unexpanded parameter pack within it is the partially-substituted pack.
+      IsPartiallyExpanded =
+          Packs.size() == 1 &&
+          PartialPackDepthIndex ==
+              std::make_pair(Info.getDeducedDepth(), Packs.front().Index);
+
+      // Skip over the pack elements that were expanded into separate arguments.
+      if (IsPartiallyExpanded)
+        PackElements += NumPartialPackArgs;
+
+      // We can also have deduced template parameters that do not actually
+      // appear in the pattern, but can be deduced by it (the type of a non-type
+      // template parameter pack, in particular). These won't have prevented us
+      // from partially expanding the pack.
+      llvm::SmallBitVector Used(TemplateParams->size());
+      MarkUsedTemplateParameters(S.Context, Pattern, /*OnlyDeduced*/true,
+                                 Info.getDeducedDepth(), Used);
+      for (int Index = Used.find_first(); Index != -1;
+           Index = Used.find_next(Index))
+        if (TemplateParams->getParam(Index)->isParameterPack())
+          AddPack(Index);
     }
-    assert(!Packs.empty() && "Pack expansion without unexpanded packs?");
 
     for (auto &Pack : Packs) {
       if (Info.PendingDeducedPacks.size() > Pack.Index)
@@ -648,18 +712,19 @@ public:
         Info.PendingDeducedPacks.resize(Pack.Index + 1);
       Info.PendingDeducedPacks[Pack.Index] = &Pack;
 
-      if (S.CurrentInstantiationScope) {
-        // If the template argument pack was explicitly specified, add that to
-        // the set of deduced arguments.
-        const TemplateArgument *ExplicitArgs;
-        unsigned NumExplicitArgs;
-        NamedDecl *PartiallySubstitutedPack =
-            S.CurrentInstantiationScope->getPartiallySubstitutedPack(
-                &ExplicitArgs, &NumExplicitArgs);
-        if (PartiallySubstitutedPack &&
-            getDepthAndIndex(PartiallySubstitutedPack) ==
-                std::make_pair(Info.getDeducedDepth(), Pack.Index))
-          Pack.New.append(ExplicitArgs, ExplicitArgs + NumExplicitArgs);
+      if (PartialPackDepthIndex ==
+            std::make_pair(Info.getDeducedDepth(), Pack.Index)) {
+        Pack.New.append(PartialPackArgs, PartialPackArgs + NumPartialPackArgs);
+        // We pre-populate the deduced value of the partially-substituted
+        // pack with the specified value. This is not entirely correct: the
+        // value is supposed to have been substituted, not deduced, but the
+        // cases where this is observable require an exact type match anyway.
+        //
+        // FIXME: If we could represent a "depth i, index j, pack elem k"
+        // parameter, we could substitute the partially-substituted pack
+        // everywhere and avoid this.
+        if (Pack.New.size() > PackElements)
+          Deduced[Pack.Index] = Pack.New[PackElements];
       }
     }
   }
@@ -671,16 +736,7 @@ public:
 
   /// Determine whether this pack has already been partially expanded into a
   /// sequence of (prior) function parameters / template arguments.
-  bool isPartiallyExpanded() {
-    if (Packs.size() != 1 || !S.CurrentInstantiationScope)
-      return false;
-
-    auto *PartiallySubstitutedPack =
-        S.CurrentInstantiationScope->getPartiallySubstitutedPack();
-    return PartiallySubstitutedPack &&
-           getDepthAndIndex(PartiallySubstitutedPack) ==
-               std::make_pair(Info.getDeducedDepth(), Packs.front().Index);
-  }
+  bool isPartiallyExpanded() { return IsPartiallyExpanded; }
 
   /// Move to deducing the next element in each pack that is being deduced.
   void nextPackElement() {
@@ -692,8 +748,13 @@ public:
       if (!Pack.New.empty() || !DeducedArg.isNull()) {
         while (Pack.New.size() < PackElements)
           Pack.New.push_back(DeducedTemplateArgument());
-        Pack.New.push_back(DeducedArg);
-        DeducedArg = DeducedTemplateArgument();
+        if (Pack.New.size() == PackElements)
+          Pack.New.push_back(DeducedArg);
+        else
+          Pack.New[PackElements] = DeducedArg;
+        DeducedArg = Pack.New.size() > PackElements + 1
+                         ? Pack.New[PackElements + 1]
+                         : DeducedTemplateArgument();
       }
     }
     ++PackElements;
@@ -730,6 +791,11 @@ public:
         std::copy(Pack.New.begin(), Pack.New.end(), ArgumentPack);
         NewPack = DeducedTemplateArgument(
             TemplateArgument(llvm::makeArrayRef(ArgumentPack, Pack.New.size())),
+            // FIXME: This is wrong, it's possible that some pack elements are
+            // deduced from an array bound and others are not:
+            //   template<typename ...T, T ...V> void g(const T (&...p)[V]);
+            //   g({1, 2, 3}, {{}, {}});
+            // ... should deduce T = {int, size_t (from array bound)}.
             Pack.New[0].wasDeducedFromArrayBound());
       }
 
@@ -779,6 +845,7 @@ private:
   SmallVectorImpl<DeducedTemplateArgument> &Deduced;
   TemplateDeductionInfo &Info;
   unsigned PackElements = 0;
+  bool IsPartiallyExpanded = false;
 
   SmallVector<DeducedPack, 2> Packs;
 };
@@ -963,6 +1030,32 @@ bool Sema::isSameOrCompatibleFunctionType(CanQualType Param,
   return Param == Arg;
 }
 
+/// Get the index of the first template parameter that was originally from the
+/// innermost template-parameter-list. This is 0 except when we concatenate
+/// the template parameter lists of a class template and a constructor template
+/// when forming an implicit deduction guide.
+static unsigned getFirstInnerIndex(FunctionTemplateDecl *FTD) {
+  auto *Guide = dyn_cast<CXXDeductionGuideDecl>(FTD->getTemplatedDecl());
+  if (!Guide || !Guide->isImplicit())
+    return 0;
+  return Guide->getDeducedTemplate()->getTemplateParameters()->size();
+}
+
+/// Determine whether a type denotes a forwarding reference.
+static bool isForwardingReference(QualType Param, unsigned FirstInnerIndex) {
+  // C++1z [temp.deduct.call]p3:
+  //   A forwarding reference is an rvalue reference to a cv-unqualified
+  //   template parameter that does not represent a template parameter of a
+  //   class template.
+  if (auto *ParamRef = Param->getAs<RValueReferenceType>()) {
+    if (ParamRef->getPointeeType().getQualifiers())
+      return false;
+    auto *TypeParm = ParamRef->getPointeeType()->getAs<TemplateTypeParmType>();
+    return TypeParm && TypeParm->getIndex() >= FirstInnerIndex;
+  }
+  return false;
+}
+
 /// \brief Deduce the template arguments by comparing the parameter type and
 /// the argument type (C++ [temp.deduct.type]).
 ///
@@ -1083,21 +1176,15 @@ DeduceTemplateArgumentsByTypeMatch(Sema &S,
       //   taking the address of a function template (14.8.2.2) or when deducing
       //   template arguments from a function declaration (14.8.2.6) and Pi and
       //   Ai are parameters of the top-level parameter-type-list of P and A,
-      //   respectively, Pi is adjusted if it is an rvalue reference to a
-      //   cv-unqualified template parameter and Ai is an lvalue reference, in
+      //   respectively, Pi is adjusted if it is a forwarding reference and Ai
+      //   is an lvalue reference, in
       //   which case the type of Pi is changed to be the template parameter
       //   type (i.e., T&& is changed to simply T). [ Note: As a result, when
       //   Pi is T&& and Ai is X&, the adjusted Pi will be T, causing T to be
       //   deduced as X&. - end note ]
       TDF &= ~TDF_TopLevelParameterTypeList;
-
-      if (const RValueReferenceType *ParamRef
-                                        = Param->getAs<RValueReferenceType>()) {
-        if (isa<TemplateTypeParmType>(ParamRef->getPointeeType()) &&
-            !ParamRef->getPointeeType().getQualifiers())
-          if (Arg->isLValueReferenceType())
-            Param = ParamRef->getPointeeType();
-      }
+      if (isForwardingReference(Param, 0) && Arg->isLValueReferenceType())
+        Param = Param->getPointeeType();
     }
   }
 
@@ -1223,9 +1310,10 @@ DeduceTemplateArgumentsByTypeMatch(Sema &S,
     // If the parameter type is not dependent, there is nothing to deduce.
     if (!Param->isDependentType()) {
       if (!(TDF & TDF_SkipNonDependent)) {
-        bool NonDeduced = (TDF & TDF_InOverloadResolution)?
-                          !S.isSameOrCompatibleFunctionType(CanParam, CanArg) :
-                          Param != Arg;
+        bool NonDeduced =
+            (TDF & TDF_AllowCompatibleFunctionType)
+                ? !S.isSameOrCompatibleFunctionType(CanParam, CanArg)
+                : Param != Arg;
         if (NonDeduced) {
           return Sema::TDK_NonDeducedMismatch;
         }
@@ -1235,10 +1323,10 @@ DeduceTemplateArgumentsByTypeMatch(Sema &S,
   } else if (!Param->isDependentType()) {
     CanQualType ParamUnqualType = CanParam.getUnqualifiedType(),
                 ArgUnqualType = CanArg.getUnqualifiedType();
-    bool Success = (TDF & TDF_InOverloadResolution)?
-                   S.isSameOrCompatibleFunctionType(ParamUnqualType,
-                                                    ArgUnqualType) :
-                   ParamUnqualType == ArgUnqualType;
+    bool Success =
+        (TDF & TDF_AllowCompatibleFunctionType)
+            ? S.isSameOrCompatibleFunctionType(ParamUnqualType, ArgUnqualType)
+            : ParamUnqualType == ArgUnqualType;
     if (Success)
       return Sema::TDK_Success;
   }
@@ -1441,17 +1529,56 @@ DeduceTemplateArgumentsByTypeMatch(Sema &S,
         return Sema::TDK_NonDeducedMismatch;
 
       // Check return types.
-      if (Sema::TemplateDeductionResult Result =
-              DeduceTemplateArgumentsByTypeMatch(
-                  S, TemplateParams, FunctionProtoParam->getReturnType(),
-                  FunctionProtoArg->getReturnType(), Info, Deduced, 0))
+      if (auto Result = DeduceTemplateArgumentsByTypeMatch(
+              S, TemplateParams, FunctionProtoParam->getReturnType(),
+              FunctionProtoArg->getReturnType(), Info, Deduced, 0))
+        return Result;
+
+      // Check parameter types.
+      if (auto Result = DeduceTemplateArguments(
+              S, TemplateParams, FunctionProtoParam->param_type_begin(),
+              FunctionProtoParam->getNumParams(),
+              FunctionProtoArg->param_type_begin(),
+              FunctionProtoArg->getNumParams(), Info, Deduced, SubTDF))
         return Result;
 
-      return DeduceTemplateArguments(
-          S, TemplateParams, FunctionProtoParam->param_type_begin(),
-          FunctionProtoParam->getNumParams(),
-          FunctionProtoArg->param_type_begin(),
-          FunctionProtoArg->getNumParams(), Info, Deduced, SubTDF);
+      if (TDF & TDF_AllowCompatibleFunctionType)
+        return Sema::TDK_Success;
+
+      // FIXME: Per core-2016/10/1019 (no corresponding core issue yet), permit
+      // deducing through the noexcept-specifier if it's part of the canonical
+      // type. libstdc++ relies on this.
+      Expr *NoexceptExpr = FunctionProtoParam->getNoexceptExpr();
+      if (NonTypeTemplateParmDecl *NTTP =
+          NoexceptExpr ? getDeducedParameterFromExpr(Info, NoexceptExpr)
+                       : nullptr) {
+        assert(NTTP->getDepth() == Info.getDeducedDepth() &&
+               "saw non-type template parameter with wrong depth");
+
+        llvm::APSInt Noexcept(1);
+        switch (FunctionProtoArg->canThrow(S.Context)) {
+        case CT_Cannot:
+          Noexcept = 1;
+          LLVM_FALLTHROUGH;
+
+        case CT_Can:
+          // We give E in noexcept(E) the "deduced from array bound" treatment.
+          // FIXME: Should we?
+          return DeduceNonTypeTemplateArgument(
+              S, TemplateParams, NTTP, Noexcept, S.Context.BoolTy,
+              /*ArrayBound*/true, Info, Deduced);
+
+        case CT_Dependent:
+          if (Expr *ArgNoexceptExpr = FunctionProtoArg->getNoexceptExpr())
+            return DeduceNonTypeTemplateArgument(
+                S, TemplateParams, NTTP, ArgNoexceptExpr, Info, Deduced);
+          // Can't deduce anything from throw(T...).
+          break;
+        }
+      }
+      // FIXME: Detect non-deduced exception specification mismatches?
+
+      return Sema::TDK_Success;
     }
 
     case Type::InjectedClassName: {
@@ -1461,7 +1588,7 @@ DeduceTemplateArgumentsByTypeMatch(Sema &S,
         ->getInjectedSpecializationType();
       assert(isa<TemplateSpecializationType>(Param) &&
              "injected class name is not a template specialization type");
-      // fall through
+      LLVM_FALLTHROUGH;
     }
 
     //     template-name<T> (where template-name refers to a class template)
@@ -1723,6 +1850,7 @@ DeduceTemplateArgumentsByTypeMatch(Sema &S,
     case Type::Decltype:
     case Type::UnaryTransform:
     case Type::Auto:
+    case Type::DeducedTemplateSpecialization:
     case Type::DependentTemplateSpecialization:
     case Type::PackExpansion:
     case Type::Pipe:
@@ -2299,7 +2427,8 @@ static Sema::TemplateDeductionResult ConvertDeducedTemplateArguments(
     bool HasDefaultArg = false;
     TemplateDecl *TD = dyn_cast<TemplateDecl>(Template);
     if (!TD) {
-      assert(isa<ClassTemplatePartialSpecializationDecl>(Template));
+      assert(isa<ClassTemplatePartialSpecializationDecl>(Template) ||
+             isa<VarTemplatePartialSpecializationDecl>(Template));
       return Sema::TDK_Incomplete;
     }
 
@@ -2335,7 +2464,7 @@ static Sema::TemplateDeductionResult ConvertDeducedTemplateArguments(
   return Sema::TDK_Success;
 }
 
-DeclContext *getAsDeclContextOrEnclosing(Decl *D) {
+static DeclContext *getAsDeclContextOrEnclosing(Decl *D) {
   if (auto *DC = dyn_cast<DeclContext>(D))
     return DC;
   return D->getDeclContext();
@@ -2363,7 +2492,8 @@ FinishTemplateArgumentDeduction(
     SmallVectorImpl<DeducedTemplateArgument> &Deduced,
     TemplateDeductionInfo &Info) {
   // Unevaluated SFINAE context.
-  EnterExpressionEvaluationContext Unevaluated(S, Sema::Unevaluated);
+  EnterExpressionEvaluationContext Unevaluated(
+      S, Sema::ExpressionEvaluationContext::Unevaluated);
   Sema::SFINAETrap Trap(S);
 
   Sema::ContextRAII SavedContext(S, getAsDeclContextOrEnclosing(Partial));
@@ -2435,13 +2565,14 @@ FinishTemplateArgumentDeduction(
 /// Complete template argument deduction for a class or variable template,
 /// when partial ordering against a partial specialization.
 // FIXME: Factor out duplication with partial specialization version above.
-Sema::TemplateDeductionResult FinishTemplateArgumentDeduction(
+static Sema::TemplateDeductionResult FinishTemplateArgumentDeduction(
     Sema &S, TemplateDecl *Template, bool PartialOrdering,
     const TemplateArgumentList &TemplateArgs,
     SmallVectorImpl<DeducedTemplateArgument> &Deduced,
     TemplateDeductionInfo &Info) {
   // Unevaluated SFINAE context.
-  EnterExpressionEvaluationContext Unevaluated(S, Sema::Unevaluated);
+  EnterExpressionEvaluationContext Unevaluated(
+      S, Sema::ExpressionEvaluationContext::Unevaluated);
   Sema::SFINAETrap Trap(S);
 
   Sema::ContextRAII SavedContext(S, getAsDeclContextOrEnclosing(Template));
@@ -2491,7 +2622,8 @@ Sema::DeduceTemplateArguments(ClassTemplatePartialSpecializationDecl *Partial,
   //   list (14.8.2).
 
   // Unevaluated SFINAE context.
-  EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
+  EnterExpressionEvaluationContext Unevaluated(
+      *this, Sema::ExpressionEvaluationContext::Unevaluated);
   SFINAETrap Trap(*this);
 
   SmallVector<DeducedTemplateArgument, 4> Deduced;
@@ -2533,7 +2665,8 @@ Sema::DeduceTemplateArguments(VarTemplatePartialSpecializationDecl *Partial,
   //   list (14.8.2).
 
   // Unevaluated SFINAE context.
-  EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
+  EnterExpressionEvaluationContext Unevaluated(
+      *this, Sema::ExpressionEvaluationContext::Unevaluated);
   SFINAETrap Trap(*this);
 
   SmallVector<DeducedTemplateArgument, 4> Deduced;
@@ -2565,12 +2698,6 @@ static bool isSimpleTemplateIdType(QualType T) {
   return false;
 }
 
-static void
-MarkUsedTemplateParameters(ASTContext &Ctx, QualType T,
-                           bool OnlyDeduced,
-                           unsigned Level,
-                           llvm::SmallBitVector &Deduced);
-
 /// \brief Substitute the explicitly-provided template arguments into the
 /// given function template according to C++ [temp.arg.explicit].
 ///
@@ -2619,7 +2746,8 @@ Sema::SubstituteExplicitTemplateArguments(
   }
 
   // Unevaluated SFINAE context.
-  EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
+  EnterExpressionEvaluationContext Unevaluated(
+      *this, Sema::ExpressionEvaluationContext::Unevaluated);
   SFINAETrap Trap(*this);
 
   // C++ [temp.arg.explicit]p3:
@@ -2633,18 +2761,15 @@ Sema::SubstituteExplicitTemplateArguments(
   // explicitly-specified template arguments against this function template,
   // and then substitute them into the function parameter types.
   SmallVector<TemplateArgument, 4> DeducedArgs;
-  InstantiatingTemplate Inst(*this, Info.getLocation(), FunctionTemplate,
-                             DeducedArgs,
-           ActiveTemplateInstantiation::ExplicitTemplateArgumentSubstitution,
-                             Info);
+  InstantiatingTemplate Inst(
+      *this, Info.getLocation(), FunctionTemplate, DeducedArgs,
+      CodeSynthesisContext::ExplicitTemplateArgumentSubstitution, Info);
   if (Inst.isInvalid())
     return TDK_InstantiationDepth;
 
-  if (CheckTemplateArgumentList(FunctionTemplate,
-                                SourceLocation(),
-                                ExplicitTemplateArgs,
-                                true,
-                                Builder) || Trap.hasErrorOccurred()) {
+  if (CheckTemplateArgumentList(FunctionTemplate, SourceLocation(),
+                                ExplicitTemplateArgs, true, Builder, false) ||
+      Trap.hasErrorOccurred()) {
     unsigned Index = Builder.size();
     if (Index >= TemplateParams->size())
       Index = TemplateParams->size() - 1;
@@ -2739,6 +2864,17 @@ Sema::SubstituteExplicitTemplateArguments(
   if (FunctionType) {
     auto EPI = Proto->getExtProtoInfo();
     EPI.ExtParameterInfos = ExtParamInfos.getPointerOrNull(ParamTypes.size());
+
+    // In C++1z onwards, exception specifications are part of the function type,
+    // so substitution into the type must also substitute into the exception
+    // specification.
+    SmallVector<QualType, 4> ExceptionStorage;
+    if (getLangOpts().CPlusPlus1z &&
+        SubstExceptionSpec(
+            Function->getLocation(), EPI.ExceptionSpec, ExceptionStorage,
+            MultiLevelTemplateArgumentList(*ExplicitArgumentList)))
+      return TDK_SubstitutionFailure;
+
     *FunctionType = BuildFunctionType(ResultType, ParamTypes,
                                       Function->getLocation(),
                                       Function->getDeclName(),
@@ -2920,16 +3056,16 @@ Sema::TemplateDeductionResult Sema::FinishTemplateArgumentDeduction(
     SmallVectorImpl<OriginalCallArg> const *OriginalCallArgs,
     bool PartialOverloading, llvm::function_ref<bool()> CheckNonDependent) {
   // Unevaluated SFINAE context.
-  EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
+  EnterExpressionEvaluationContext Unevaluated(
+      *this, Sema::ExpressionEvaluationContext::Unevaluated);
   SFINAETrap Trap(*this);
 
   // Enter a new template instantiation context while we instantiate the
   // actual function declaration.
   SmallVector<TemplateArgument, 4> DeducedArgs(Deduced.begin(), Deduced.end());
-  InstantiatingTemplate Inst(*this, Info.getLocation(), FunctionTemplate,
-                             DeducedArgs,
-              ActiveTemplateInstantiation::DeducedTemplateArgumentSubstitution,
-                             Info);
+  InstantiatingTemplate Inst(
+      *this, Info.getLocation(), FunctionTemplate, DeducedArgs,
+      CodeSynthesisContext::DeducedTemplateArgumentSubstitution, Info);
   if (Inst.isInvalid())
     return TDK_InstantiationDepth;
 
@@ -3186,12 +3322,9 @@ ResolveOverloadForDeduction(Sema &S, TemplateParameterList *TemplateParams,
 /// \returns true if the caller should not attempt to perform any template
 /// argument deduction based on this P/A pair because the argument is an
 /// overloaded function set that could not be resolved.
-static bool AdjustFunctionParmAndArgTypesForDeduction(Sema &S,
-                                          TemplateParameterList *TemplateParams,
-                                                      QualType &ParamType,
-                                                      QualType &ArgType,
-                                                      Expr *Arg,
-                                                      unsigned &TDF) {
+static bool AdjustFunctionParmAndArgTypesForDeduction(
+    Sema &S, TemplateParameterList *TemplateParams, unsigned FirstInnerIndex,
+    QualType &ParamType, QualType &ArgType, Expr *Arg, unsigned &TDF) {
   // C++0x [temp.deduct.call]p3:
   //   If P is a cv-qualified type, the top level cv-qualifiers of P's type
   //   are ignored for type deduction.
@@ -3222,13 +3355,10 @@ static bool AdjustFunctionParmAndArgTypesForDeduction(Sema &S,
       ArgType = Arg->getType();
     }
 
-    // C++0x [temp.deduct.call]p3:
-    //   If P is an rvalue reference to a cv-unqualified template
-    //   parameter and the argument is an lvalue, the type "lvalue
-    //   reference to A" is used in place of A for type deduction.
-    if (ParamRefType->isRValueReferenceType() &&
-        !ParamType.getQualifiers() &&
-        isa<TemplateTypeParmType>(ParamType) &&
+    // C++1z [temp.deduct.call]p3:
+    //   If P is a forwarding reference and the argument is an lvalue, the type
+    //   "lvalue reference to A" is used in place of A for type deduction.
+    if (isForwardingReference(QualType(ParamRefType, 0), FirstInnerIndex) &&
         Arg->isLValue())
       ArgType = S.Context.getLValueReferenceType(ArgType);
   } else {
@@ -3287,8 +3417,8 @@ hasDeducibleTemplateParameters(Sema &S, FunctionTemplateDecl *FunctionTemplate,
                                QualType T);
 
 static Sema::TemplateDeductionResult DeduceTemplateArgumentsFromCallArgument(
-    Sema &S, TemplateParameterList *TemplateParams, QualType ParamType,
-    Expr *Arg, TemplateDeductionInfo &Info,
+    Sema &S, TemplateParameterList *TemplateParams, unsigned FirstInnerIndex,
+    QualType ParamType, Expr *Arg, TemplateDeductionInfo &Info,
     SmallVectorImpl<DeducedTemplateArgument> &Deduced,
     SmallVectorImpl<Sema::OriginalCallArg> &OriginalCallArgs,
     bool DecomposedParam, unsigned ArgIdx, unsigned TDF);
@@ -3326,7 +3456,7 @@ static Sema::TemplateDeductionResult DeduceFromInitializerList(
   if (ElTy->isDependentType()) {
     for (Expr *E : ILE->inits()) {
       if (auto Result = DeduceTemplateArgumentsFromCallArgument(
-              S, TemplateParams, ElTy, E, Info, Deduced, OriginalCallArgs, true,
+              S, TemplateParams, 0, ElTy, E, Info, Deduced, OriginalCallArgs, true,
               ArgIdx, TDF))
         return Result;
     }
@@ -3340,10 +3470,12 @@ static Sema::TemplateDeductionResult DeduceFromInitializerList(
             getDeducedParameterFromExpr(Info, DependentArrTy->getSizeExpr())) {
       // We can perform template argument deduction for the given non-type
       // template parameter.
-      llvm::APInt Size(S.Context.getIntWidth(NTTP->getType()),
-                       ILE->getNumInits());
+      // C++ [temp.deduct.type]p13:
+      //   The type of N in the type T[N] is std::size_t.
+      QualType T = S.Context.getSizeType();
+      llvm::APInt Size(S.Context.getIntWidth(T), ILE->getNumInits());
       if (auto Result = DeduceNonTypeTemplateArgument(
-              S, TemplateParams, NTTP, llvm::APSInt(Size), NTTP->getType(),
+              S, TemplateParams, NTTP, llvm::APSInt(Size), T,
               /*ArrayBound=*/true, Info, Deduced))
         return Result;
     }
@@ -3355,8 +3487,8 @@ static Sema::TemplateDeductionResult DeduceFromInitializerList(
 /// \brief Perform template argument deduction per [temp.deduct.call] for a
 ///        single parameter / argument pair.
 static Sema::TemplateDeductionResult DeduceTemplateArgumentsFromCallArgument(
-    Sema &S, TemplateParameterList *TemplateParams, QualType ParamType,
-    Expr *Arg, TemplateDeductionInfo &Info,
+    Sema &S, TemplateParameterList *TemplateParams, unsigned FirstInnerIndex,
+    QualType ParamType, Expr *Arg, TemplateDeductionInfo &Info,
     SmallVectorImpl<DeducedTemplateArgument> &Deduced,
     SmallVectorImpl<Sema::OriginalCallArg> &OriginalCallArgs,
     bool DecomposedParam, unsigned ArgIdx, unsigned TDF) {
@@ -3365,8 +3497,8 @@ static Sema::TemplateDeductionResult DeduceTemplateArgumentsFromCallArgument(
 
   //   If P is a reference type [...]
   //   If P is a cv-qualified type [...]
-  if (AdjustFunctionParmAndArgTypesForDeduction(S, TemplateParams, ParamType,
-                                                ArgType, Arg, TDF))
+  if (AdjustFunctionParmAndArgTypesForDeduction(
+          S, TemplateParams, FirstInnerIndex, ParamType, ArgType, Arg, TDF))
     return Sema::TDK_Success;
 
   //   If [...] the argument is a non-empty initializer list [...]
@@ -3422,6 +3554,8 @@ Sema::TemplateDeductionResult Sema::DeduceTemplateArguments(
   FunctionDecl *Function = FunctionTemplate->getTemplatedDecl();
   unsigned NumParams = Function->getNumParams();
 
+  unsigned FirstInnerIndex = getFirstInnerIndex(FunctionTemplate);
+
   // C++ [temp.deduct.call]p1:
   //   Template argument deduction is done by comparing each function template
   //   parameter type (call it P) with the type of the corresponding argument
@@ -3476,7 +3610,7 @@ Sema::TemplateDeductionResult Sema::DeduceTemplateArguments(
 
     //   ... with the type of the corresponding argument
     return DeduceTemplateArgumentsFromCallArgument(
-        *this, TemplateParams, ParamType, Args[ArgIdx], Info, Deduced,
+        *this, TemplateParams, FirstInnerIndex, ParamType, Args[ArgIdx], Info, Deduced,
         OriginalCallArgs, /*Decomposed*/false, ArgIdx, /*TDF*/ 0);
   };
 
@@ -3635,13 +3769,6 @@ Sema::TemplateDeductionResult Sema::DeduceTemplateArguments(
     = FunctionTemplate->getTemplateParameters();
   QualType FunctionType = Function->getType();
 
-  // When taking the address of a function, we require convertibility of
-  // the resulting function type. Otherwise, we allow arbitrary mismatches
-  // of calling convention, noreturn, and noexcept.
-  if (!IsAddressOfFunction)
-    ArgFunctionType = adjustCCAndNoReturn(ArgFunctionType, FunctionType,
-                                          /*AdjustExceptionSpec*/true);
-
   // Substitute any explicit template arguments.
   LocalInstantiationScope InstScope(*this);
   SmallVector<DeducedTemplateArgument, 4> Deduced;
@@ -3658,8 +3785,16 @@ Sema::TemplateDeductionResult Sema::DeduceTemplateArguments(
     NumExplicitlySpecified = Deduced.size();
   }
 
+  // When taking the address of a function, we require convertibility of
+  // the resulting function type. Otherwise, we allow arbitrary mismatches
+  // of calling convention and noreturn.
+  if (!IsAddressOfFunction)
+    ArgFunctionType = adjustCCAndNoReturn(ArgFunctionType, FunctionType,
+                                          /*AdjustExceptionSpec*/false);
+
   // Unevaluated SFINAE context.
-  EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
+  EnterExpressionEvaluationContext Unevaluated(
+      *this, Sema::ExpressionEvaluationContext::Unevaluated);
   SFINAETrap Trap(*this);
 
   Deduced.resize(TemplateParams->size());
@@ -3676,9 +3811,8 @@ Sema::TemplateDeductionResult Sema::DeduceTemplateArguments(
   }
 
   if (!ArgFunctionType.isNull()) {
-    unsigned TDF = TDF_TopLevelParameterTypeList;
-    if (IsAddressOfFunction)
-      TDF |= TDF_InOverloadResolution;
+    unsigned TDF =
+        TDF_TopLevelParameterTypeList | TDF_AllowCompatibleFunctionType;
     // Deduce template arguments from the function type.
     if (TemplateDeductionResult Result
           = DeduceTemplateArgumentsByTypeMatch(*this, TemplateParams,
@@ -3709,7 +3843,7 @@ Sema::TemplateDeductionResult Sema::DeduceTemplateArguments(
       !ResolveExceptionSpec(Info.getLocation(), SpecializationFPT))
     return TDK_MiscellaneousDeductionFailure;
 
-  // Adjust the exception specification of the argument again to match the
+  // Adjust the exception specification of the argument to match the
   // substituted and resolved type we just formed. (Calling convention and
   // noreturn can't be dependent, so we don't actually need this for them
   // right now.)
@@ -3907,7 +4041,8 @@ Sema::DeduceTemplateArguments(FunctionTemplateDecl *ConversionTemplate,
   }
 
   // Unevaluated SFINAE context.
-  EnterExpressionEvaluationContext Unevaluated(*this, Sema::Unevaluated);
+  EnterExpressionEvaluationContext Unevaluated(
+      *this, Sema::ExpressionEvaluationContext::Unevaluated);
   SFINAETrap Trap(*this);
 
   // C++ [temp.deduct.conv]p1:
@@ -4020,17 +4155,26 @@ Sema::TemplateDeductionResult Sema::DeduceTemplateArguments(
 }
 
 namespace {
-  /// Substitute the 'auto' type specifier within a type for a given replacement
-  /// type.
-  class SubstituteAutoTransform :
-    public TreeTransform<SubstituteAutoTransform> {
+  /// Substitute the 'auto' specifier or deduced template specialization type
+  /// specifier within a type for a given replacement type.
+  class SubstituteDeducedTypeTransform :
+      public TreeTransform<SubstituteDeducedTypeTransform> {
     QualType Replacement;
-    bool UseAutoSugar;
+    bool UseTypeSugar;
   public:
-    SubstituteAutoTransform(Sema &SemaRef, QualType Replacement,
-                            bool UseAutoSugar = true)
-        : TreeTransform<SubstituteAutoTransform>(SemaRef),
-          Replacement(Replacement), UseAutoSugar(UseAutoSugar) {}
+    SubstituteDeducedTypeTransform(Sema &SemaRef, QualType Replacement,
+                            bool UseTypeSugar = true)
+        : TreeTransform<SubstituteDeducedTypeTransform>(SemaRef),
+          Replacement(Replacement), UseTypeSugar(UseTypeSugar) {}
+
+    QualType TransformDesugared(TypeLocBuilder &TLB, DeducedTypeLoc TL) {
+      assert(isa<TemplateTypeParmType>(Replacement) &&
+             "unexpected unsugared replacement kind");
+      QualType Result = Replacement;
+      TemplateTypeParmTypeLoc NewTL = TLB.push<TemplateTypeParmTypeLoc>(Result);
+      NewTL.setNameLoc(TL.getNameLoc());
+      return Result;
+    }
 
     QualType TransformAutoType(TypeLocBuilder &TLB, AutoTypeLoc TL) {
       // If we're building the type pattern to deduce against, don't wrap the
@@ -4040,21 +4184,29 @@ namespace {
       //   auto &&lref = lvalue;
       // must transform into "rvalue reference to T" not "rvalue reference to
       // auto type deduced as T" in order for [temp.deduct.call]p3 to apply.
-      if (!UseAutoSugar) {
-        assert(isa<TemplateTypeParmType>(Replacement) &&
-               "unexpected unsugared replacement kind");
-        QualType Result = Replacement;
-        TemplateTypeParmTypeLoc NewTL =
-          TLB.push<TemplateTypeParmTypeLoc>(Result);
-        NewTL.setNameLoc(TL.getNameLoc());
-        return Result;
-      } else {
-        QualType Result = SemaRef.Context.getAutoType(
-            Replacement, TL.getTypePtr()->getKeyword(), Replacement.isNull());
-        AutoTypeLoc NewTL = TLB.push<AutoTypeLoc>(Result);
-        NewTL.setNameLoc(TL.getNameLoc());
-        return Result;
-      }
+      //
+      // FIXME: Is this still necessary?
+      if (!UseTypeSugar)
+        return TransformDesugared(TLB, TL);
+
+      QualType Result = SemaRef.Context.getAutoType(
+          Replacement, TL.getTypePtr()->getKeyword(), Replacement.isNull());
+      auto NewTL = TLB.push<AutoTypeLoc>(Result);
+      NewTL.setNameLoc(TL.getNameLoc());
+      return Result;
+    }
+
+    QualType TransformDeducedTemplateSpecializationType(
+        TypeLocBuilder &TLB, DeducedTemplateSpecializationTypeLoc TL) {
+      if (!UseTypeSugar)
+        return TransformDesugared(TLB, TL);
+
+      QualType Result = SemaRef.Context.getDeducedTemplateSpecializationType(
+          TL.getTypePtr()->getTemplateName(),
+          Replacement, Replacement.isNull());
+      auto NewTL = TLB.push<DeducedTemplateSpecializationTypeLoc>(Result);
+      NewTL.setNameLoc(TL.getNameLoc());
+      return Result;
     }
 
     ExprResult TransformLambdaExpr(LambdaExpr *E) {
@@ -4105,7 +4257,7 @@ Sema::DeduceAutoType(TypeLoc Type, Expr *&Init, QualType &Result,
 
   if (!DependentDeductionDepth &&
       (Type.getType()->isDependentType() || Init->isTypeDependent())) {
-    Result = SubstituteAutoTransform(*this, QualType()).Apply(Type);
+    Result = SubstituteDeducedTypeTransform(*this, QualType()).Apply(Type);
     assert(!Result.isNull() && "substituting DependentTy can't fail");
     return DAR_Succeeded;
   }
@@ -4128,7 +4280,7 @@ Sema::DeduceAutoType(TypeLoc Type, Expr *&Init, QualType &Result,
         return DAR_FailedAlreadyDiagnosed;
       // FIXME: Support a non-canonical deduced type for 'auto'.
       Deduced = Context.getCanonicalType(Deduced);
-      Result = SubstituteAutoTransform(*this, Deduced).Apply(Type);
+      Result = SubstituteDeducedTypeTransform(*this, Deduced).Apply(Type);
       if (Result.isNull())
         return DAR_FailedAlreadyDiagnosed;
       return DAR_Succeeded;
@@ -4153,7 +4305,7 @@ Sema::DeduceAutoType(TypeLoc Type, Expr *&Init, QualType &Result,
       Loc, Loc, TemplParamPtr, Loc, nullptr);
 
   QualType FuncParam =
-      SubstituteAutoTransform(*this, TemplArg, /*UseAutoSugar*/false)
+      SubstituteDeducedTypeTransform(*this, TemplArg, /*UseTypeSugar*/false)
           .Apply(Type);
   assert(!FuncParam.isNull() &&
          "substituting template parameter for 'auto' failed");
@@ -4168,7 +4320,7 @@ Sema::DeduceAutoType(TypeLoc Type, Expr *&Init, QualType &Result,
   // might acquire a matching type in the instantiation.
   auto DeductionFailed = [&]() -> DeduceAutoResult {
     if (Init->isTypeDependent()) {
-      Result = SubstituteAutoTransform(*this, QualType()).Apply(Type);
+      Result = SubstituteDeducedTypeTransform(*this, QualType()).Apply(Type);
       assert(!Result.isNull() && "substituting DependentTy can't fail");
       return DAR_Succeeded;
     }
@@ -4187,7 +4339,7 @@ Sema::DeduceAutoType(TypeLoc Type, Expr *&Init, QualType &Result,
 
     for (unsigned i = 0, e = InitList->getNumInits(); i < e; ++i) {
       if (DeduceTemplateArgumentsFromCallArgument(
-              *this, TemplateParamsSt.get(), TemplArg, InitList->getInit(i),
+              *this, TemplateParamsSt.get(), 0, TemplArg, InitList->getInit(i),
               Info, Deduced, OriginalCallArgs, /*Decomposed*/ true,
               /*ArgIdx*/ 0, /*TDF*/ 0))
         return DeductionFailed();
@@ -4199,7 +4351,7 @@ Sema::DeduceAutoType(TypeLoc Type, Expr *&Init, QualType &Result,
     }
 
     if (DeduceTemplateArgumentsFromCallArgument(
-            *this, TemplateParamsSt.get(), FuncParam, Init, Info, Deduced,
+            *this, TemplateParamsSt.get(), 0, FuncParam, Init, Info, Deduced,
             OriginalCallArgs, /*Decomposed*/ false, /*ArgIdx*/ 0, /*TDF*/ 0))
       return DeductionFailed();
   }
@@ -4216,7 +4368,7 @@ Sema::DeduceAutoType(TypeLoc Type, Expr *&Init, QualType &Result,
       return DAR_FailedAlreadyDiagnosed;
   }
 
-  Result = SubstituteAutoTransform(*this, DeducedType).Apply(Type);
+  Result = SubstituteDeducedTypeTransform(*this, DeducedType).Apply(Type);
   if (Result.isNull())
     return DAR_FailedAlreadyDiagnosed;
 
@@ -4239,15 +4391,22 @@ QualType Sema::SubstAutoType(QualType TypeWithAuto,
                              QualType TypeToReplaceAuto) {
   if (TypeToReplaceAuto->isDependentType())
     TypeToReplaceAuto = QualType();
-  return SubstituteAutoTransform(*this, TypeToReplaceAuto)
+  return SubstituteDeducedTypeTransform(*this, TypeToReplaceAuto)
       .TransformType(TypeWithAuto);
 }
 
-TypeSourceInfo* Sema::SubstAutoTypeSourceInfo(TypeSourceInfo *TypeWithAuto,
-                             QualType TypeToReplaceAuto) {
+TypeSourceInfo *Sema::SubstAutoTypeSourceInfo(TypeSourceInfo *TypeWithAuto,
+                                              QualType TypeToReplaceAuto) {
   if (TypeToReplaceAuto->isDependentType())
     TypeToReplaceAuto = QualType();
-  return SubstituteAutoTransform(*this, TypeToReplaceAuto)
+  return SubstituteDeducedTypeTransform(*this, TypeToReplaceAuto)
+      .TransformType(TypeWithAuto);
+}
+
+QualType Sema::ReplaceAutoType(QualType TypeWithAuto,
+                               QualType TypeToReplaceAuto) {
+  return SubstituteDeducedTypeTransform(*this, TypeToReplaceAuto,
+                                        /*UseTypeSugar*/ false)
       .TransformType(TypeWithAuto);
 }
 
@@ -4848,13 +5007,6 @@ bool Sema::isTemplateTemplateParameterAtLeastAsSpecializedAs(
   return isAtLeastAsSpecializedAs(*this, PType, AType, AArg, Info);
 }
 
-static void
-MarkUsedTemplateParameters(ASTContext &Ctx,
-                           const TemplateArgument &TemplateArg,
-                           bool OnlyDeduced,
-                           unsigned Depth,
-                           llvm::SmallBitVector &Used);
-
 /// \brief Mark the template parameters that are used by the given
 /// expression.
 static void
@@ -4996,6 +5148,7 @@ MarkUsedTemplateParameters(ASTContext &Ctx, QualType T,
                                cast<DependentSizedArrayType>(T)->getSizeExpr(),
                                OnlyDeduced, Depth, Used);
     // Fall through to check the element type
+    LLVM_FALLTHROUGH;
 
   case Type::ConstantArray:
   case Type::IncompleteArray:
@@ -5028,6 +5181,8 @@ MarkUsedTemplateParameters(ASTContext &Ctx, QualType T,
     for (unsigned I = 0, N = Proto->getNumParams(); I != N; ++I)
       MarkUsedTemplateParameters(Ctx, Proto->getParamType(I), OnlyDeduced,
                                  Depth, Used);
+    if (auto *E = Proto->getNoexceptExpr())
+      MarkUsedTemplateParameters(Ctx, E, OnlyDeduced, Depth, Used);
     break;
   }
 
@@ -5154,8 +5309,9 @@ MarkUsedTemplateParameters(ASTContext &Ctx, QualType T,
     break;
 
   case Type::Auto:
+  case Type::DeducedTemplateSpecialization:
     MarkUsedTemplateParameters(Ctx,
-                               cast<AutoType>(T)->getDeducedType(),
+                               cast<DeducedType>(T)->getDeducedType(),
                                OnlyDeduced, Depth, Used);
 
   // None of these types have any template parameters in them.