Revert INTERFACE_LINK_LIBRARIES_DIRECT feature for 3.23 branch

Revert commit f3ad061858 (Add usage requirements to update direct link
dependencies, 2022-01-12, v3.23.0-rc1~44^2) and the property storage
updates in its predecessor commit 193a999cd5 (cmTarget: Add
INTERFACE_LINK_LIBRARIES_DIRECT{,_EXCLUDE} backtrace storage,
2022-01-06, v3.23.0-rc1~44^2~1) from the 3.23 release branch.

After initial experience using the feature in practice, additional
design considerations have been raised for discussion in the original
issue.  To avoid rushing this for the 3.23 series, we've decided to
revert the feature for now so it can be revised for a future release.

Issue: #22496

1 files changed, 14 insertions, 166 deletions

diff --git a/Source/cmGeneratorTarget.cxx b/Source/cmGeneratorTarget.cxx
index 63cf2ec0ea..a8bc91cecc 100644
--- a/Source/cmGeneratorTarget.cxx
+++ b/Source/cmGeneratorTarget.cxx
@@ -58,10 +58,6 @@ using LinkInterfaceFor = cmGeneratorTarget::LinkInterfaceFor;
 const cmsys::RegularExpression FrameworkRegularExpression(
   "^(.*/)?([^/]*)\\.framework/(.*)$");
 const std::string kINTERFACE_LINK_LIBRARIES = "INTERFACE_LINK_LIBRARIES";
-const std::string kINTERFACE_LINK_LIBRARIES_DIRECT =
-  "INTERFACE_LINK_LIBRARIES_DIRECT";
-const std::string kINTERFACE_LINK_LIBRARIES_DIRECT_EXCLUDE =
-  "INTERFACE_LINK_LIBRARIES_DIRECT_EXCLUDE";
 }
 
 template <>
@@ -6671,10 +6667,12 @@ cm::optional<cmLinkItem> cmGeneratorTarget::LookupLinkItem(
   return maybeItem;
 }
 
-void cmGeneratorTarget::ExpandLinkItems(
-  std::string const& prop, cmBTStringRange entries, std::string const& config,
-  cmGeneratorTarget const* headTarget, LinkInterfaceFor interfaceFor,
-  LinkInterfaceField field, cmLinkInterface& iface) const
+void cmGeneratorTarget::ExpandLinkItems(std::string const& prop,
+                                        cmBTStringRange entries,
+                                        std::string const& config,
+                                        cmGeneratorTarget const* headTarget,
+                                        LinkInterfaceFor interfaceFor,
+                                        cmLinkInterface& iface) const
 {
   if (entries.empty()) {
     return;
@@ -6698,19 +6696,9 @@ void cmGeneratorTarget::ExpandLinkItems(
                     this, headTarget->LinkerLanguage));
     for (std::string const& lib : libs) {
       if (cm::optional<cmLinkItem> maybeItem = this->LookupLinkItem(
-            lib, cge->GetBacktrace(), &scope,
-            field == LinkInterfaceField::Libraries ? LookupSelf::No
-                                                   : LookupSelf::Yes)) {
+            lib, cge->GetBacktrace(), &scope, LookupSelf::No)) {
         cmLinkItem item = std::move(*maybeItem);
 
-        if (field == LinkInterfaceField::HeadInclude) {
-          iface.HeadInclude.emplace_back(std::move(item));
-          continue;
-        }
-        if (field == LinkInterfaceField::HeadExclude) {
-          iface.HeadExclude.emplace_back(std::move(item));
-          continue;
-        }
         if (!item.Target) {
           // Report explicitly linked object files separately.
           std::string const& maybeObj = item.AsStr();
@@ -7181,9 +7169,7 @@ void cmGeneratorTarget::ComputeLinkInterfaceLibraries(
                            this->GetPolicyStatusCMP0022() != cmPolicies::WARN);
   if (cmp0022NEW) {
     // CMP0022 NEW behavior is to use INTERFACE_LINK_LIBRARIES.
-    haveExplicitLibraries = !this->Target->GetLinkInterfaceEntries().empty() ||
-      !this->Target->GetLinkInterfaceDirectEntries().empty() ||
-      !this->Target->GetLinkInterfaceDirectExcludeEntries().empty();
+    haveExplicitLibraries = !this->Target->GetLinkInterfaceEntries().empty();
   } else {
     // CMP0022 OLD behavior is to use LINK_INTERFACE_LIBRARIES if set on a
     // shared lib or executable.
@@ -7248,24 +7234,15 @@ void cmGeneratorTarget::ComputeLinkInterfaceLibraries(
   if (cmp0022NEW) {
     // The interface libraries are specified by INTERFACE_LINK_LIBRARIES.
     // Use its special representation directly to get backtraces.
-    this->ExpandLinkItems(
-      kINTERFACE_LINK_LIBRARIES, this->Target->GetLinkInterfaceEntries(),
-      config, headTarget, interfaceFor, LinkInterfaceField::Libraries, iface);
-    this->ExpandLinkItems(kINTERFACE_LINK_LIBRARIES_DIRECT,
-                          this->Target->GetLinkInterfaceDirectEntries(),
-                          config, headTarget, interfaceFor,
-                          LinkInterfaceField::HeadInclude, iface);
-    this->ExpandLinkItems(kINTERFACE_LINK_LIBRARIES_DIRECT_EXCLUDE,
-                          this->Target->GetLinkInterfaceDirectExcludeEntries(),
-                          config, headTarget, interfaceFor,
-                          LinkInterfaceField::HeadExclude, iface);
+    this->ExpandLinkItems(kINTERFACE_LINK_LIBRARIES,
+                          this->Target->GetLinkInterfaceEntries(), config,
+                          headTarget, interfaceFor, iface);
   } else if (explicitLibrariesCMP0022OLD) {
     // The interface libraries have been explicitly set in pre-CMP0022 style.
     std::vector<BT<std::string>> entries;
     entries.emplace_back(*explicitLibrariesCMP0022OLD);
     this->ExpandLinkItems(linkIfacePropCMP0022OLD, cmMakeRange(entries),
-                          config, headTarget, interfaceFor,
-                          LinkInterfaceField::Libraries, iface);
+                          config, headTarget, interfaceFor, iface);
   }
 
   // If the link interface is explicit, do not fall back to the link impl.
@@ -7285,8 +7262,7 @@ void cmGeneratorTarget::ComputeLinkInterfaceLibraries(
       cmLinkInterface ifaceNew;
       this->ExpandLinkItems(kINTERFACE_LINK_LIBRARIES,
                             this->Target->GetLinkInterfaceEntries(), config,
-                            headTarget, interfaceFor,
-                            LinkInterfaceField::Libraries, ifaceNew);
+                            headTarget, interfaceFor, ifaceNew);
       if (ifaceNew.Libraries != iface.Libraries) {
         std::string oldLibraries = cmJoin(impl->Libraries, ";");
         std::string newLibraries = cmJoin(ifaceNew.Libraries, ";");
@@ -7426,17 +7402,8 @@ const cmLinkInterface* cmGeneratorTarget::GetImportLinkInterface(
     iface.LibrariesDone = true;
     iface.Multiplicity = info->Multiplicity;
     cmExpandList(info->Languages, iface.Languages);
-    this->ExpandLinkItems(kINTERFACE_LINK_LIBRARIES_DIRECT,
-                          cmMakeRange(info->LibrariesHeadInclude), config,
-                          headTarget, interfaceFor,
-                          LinkInterfaceField::HeadInclude, iface);
-    this->ExpandLinkItems(kINTERFACE_LINK_LIBRARIES_DIRECT_EXCLUDE,
-                          cmMakeRange(info->LibrariesHeadExclude), config,
-                          headTarget, interfaceFor,
-                          LinkInterfaceField::HeadExclude, iface);
     this->ExpandLinkItems(info->LibrariesProp, cmMakeRange(info->Libraries),
-                          config, headTarget, interfaceFor,
-                          LinkInterfaceField::Libraries, iface);
+                          config, headTarget, interfaceFor, iface);
     std::vector<std::string> deps = cmExpandedList(info->SharedDeps);
     LookupLinkItemScope scope{ this->LocalGenerator };
     for (std::string const& dep : deps) {
@@ -7529,14 +7496,6 @@ void cmGeneratorTarget::ComputeImportInfo(std::string const& desired_config,
       }
     }
   }
-  for (BT<std::string> const& entry :
-       this->Target->GetLinkInterfaceDirectEntries()) {
-    info.LibrariesHeadInclude.emplace_back(entry);
-  }
-  for (BT<std::string> const& entry :
-       this->Target->GetLinkInterfaceDirectExcludeEntries()) {
-    info.LibrariesHeadExclude.emplace_back(entry);
-  }
   if (this->GetType() == cmStateEnums::INTERFACE_LIBRARY) {
     if (loc) {
       info.LibName = *loc;
@@ -7970,112 +7929,6 @@ bool cmGeneratorTarget::IsNullImpliedByLinkLibraries(
   return cm::contains(this->LinkImplicitNullProperties, p);
 }
 
-namespace {
-class TransitiveLinkImpl
-{
-  cmGeneratorTarget const* Self;
-  std::string const& Config;
-  cmLinkImplementation& Impl;
-
-  std::set<cmLinkItem> Emitted;
-  std::set<cmLinkItem> Excluded;
-  std::unordered_set<cmGeneratorTarget const*> Followed;
-
-  void Follow(cmGeneratorTarget const* target);
-
-public:
-  TransitiveLinkImpl(cmGeneratorTarget const* self, std::string const& config,
-                     cmLinkImplementation& impl)
-    : Self(self)
-    , Config(config)
-    , Impl(impl)
-  {
-  }
-
-  void Compute();
-};
-
-void TransitiveLinkImpl::Follow(cmGeneratorTarget const* target)
-{
-  if (!target || !this->Followed.insert(target).second ||
-      target->GetPolicyStatusCMP0022() == cmPolicies::OLD ||
-      target->GetPolicyStatusCMP0022() == cmPolicies::WARN) {
-    return;
-  }
-
-  // Get this target's usage requirements.
-  cmLinkInterfaceLibraries const* iface = target->GetLinkInterfaceLibraries(
-    this->Config, this->Self, LinkInterfaceFor::Usage);
-  if (!iface) {
-    return;
-  }
-  if (iface->HadContextSensitiveCondition) {
-    this->Impl.HadContextSensitiveCondition = true;
-  }
-
-  // Process 'INTERFACE_LINK_LIBRARIES_DIRECT' usage requirements.
-  for (cmLinkItem const& item : iface->HeadInclude) {
-    // Inject direct dependencies from the item's usage requirements
-    // before the item itself.
-    this->Follow(item.Target);
-
-    // Add the item itself, but at most once.
-    if (this->Emitted.insert(item).second) {
-      this->Impl.Libraries.emplace_back(item, /* checkCMP0027= */ false);
-    }
-  }
-
-  // Follow transitive dependencies.
-  for (cmLinkItem const& item : iface->Libraries) {
-    this->Follow(item.Target);
-  }
-
-  // Record exclusions from 'INTERFACE_LINK_LIBRARIES_DIRECT_EXCLUDE'
-  // usage requirements.
-  for (cmLinkItem const& item : iface->HeadExclude) {
-    this->Excluded.insert(item);
-  }
-}
-
-void TransitiveLinkImpl::Compute()
-{
-  // Save the original items and start with an empty list.
-  std::vector<cmLinkImplItem> original = std::move(this->Impl.Libraries);
-
-  // Avoid injecting any original items as usage requirements.
-  // This gives LINK_LIBRARIES final control over the order
-  // if it explicitly lists everything.
-  this->Emitted.insert(original.cbegin(), original.cend());
-
-  // Process each original item.
-  for (cmLinkImplItem& item : original) {
-    // Inject direct dependencies listed in 'INTERFACE_LINK_LIBRARIES_DIRECT'
-    // usage requirements before the item itself.
-    this->Follow(item.Target);
-
-    // Add the item itself.
-    this->Impl.Libraries.emplace_back(std::move(item));
-  }
-
-  // Remove items listed in 'INTERFACE_LINK_LIBRARIES_DIRECT_EXCLUDE'
-  // usage requirements found through any dependency above.
-  this->Impl.Libraries.erase(
-    std::remove_if(this->Impl.Libraries.begin(), this->Impl.Libraries.end(),
-                   [this](cmLinkImplItem const& item) {
-                     return this->Excluded.find(item) != this->Excluded.end();
-                   }),
-    this->Impl.Libraries.end());
-}
-
-void ComputeLinkImplTransitive(cmGeneratorTarget const* self,
-                               std::string const& config,
-                               cmLinkImplementation& impl)
-{
-  TransitiveLinkImpl transitiveLinkImpl(self, config, impl);
-  transitiveLinkImpl.Compute();
-}
-}
-
 void cmGeneratorTarget::ComputeLinkImplementationLibraries(
   const std::string& config, cmOptionalLinkImplementation& impl,
   cmGeneratorTarget const* head) const
@@ -8182,11 +8035,6 @@ void cmGeneratorTarget::ComputeLinkImplementationLibraries(
     cge->GetMaxLanguageStandard(this, this->MaxLanguageStandards);
   }
 
-  // Update the list of direct link dependencies from usage requirements.
-  if (head == this) {
-    ComputeLinkImplTransitive(this, config, impl);
-  }
-
   // Get the list of configurations considered to be DEBUG.
   std::vector<std::string> debugConfigs =
     this->Makefile->GetCMakeInstance()->GetDebugConfigs();