VS: Generate a custom command only in the least dependent target

If a custom command is assigned to multiple targets, generate the build
rule only in the least-dependent `.vcxproj` file.  Otherwise MSBuild
will run the command on the first build of a dependent target even if
its dependencies already brought the command up to date (in order to
populates its build log).

Generate targets in least-to-most-dependent order, and assign a custom
command to the least dependent target.

Added cmLocalVisualStudio10Generator::GenerateTargetsDepthFirst to call
cmVisualStudio10TargetGenerator::Generate in least-dependent order.

Moved SourcesVisited from cmVisualStudio10TargetGenerator to
cmLocalVisualStudio10Generator to avoid attaching a custom command to
multiple targets among the local generator.

Fixes: #16767

1 files changed, 39 insertions, 13 deletions

diff --git a/Source/cmLocalVisualStudio10Generator.cxx b/Source/cmLocalVisualStudio10Generator.cxx
index 2803d4a..5b6e781 100644
--- a/Source/cmLocalVisualStudio10Generator.cxx
+++ b/Source/cmLocalVisualStudio10Generator.cxx
@@ -62,21 +62,47 @@ cmLocalVisualStudio10Generator::~cmLocalVisualStudio10Generator()
 {
 }
 
+void cmLocalVisualStudio10Generator::GenerateTargetsDepthFirst(
+  cmGeneratorTarget* target, std::vector<cmGeneratorTarget*>& remaining)
+{
+  if (target->GetType() == cmStateEnums::INTERFACE_LIBRARY) {
+    return;
+  }
+  // Find this target in the list of remaining targets.
+  auto it = std::find(remaining.begin(), remaining.end(), target);
+  if (it == remaining.end()) {
+    // This target was already handled.
+    return;
+  }
+  // Remove this target from the list of remaining targets because
+  // we are handling it now.
+  *it = nullptr;
+  auto& deps = this->GlobalGenerator->GetTargetDirectDepends(target);
+  for (auto& d : deps) {
+    // FIXME: Revise CreateSingleVCProj so we do not have to drop `const` here.
+    auto dependee = const_cast<cmGeneratorTarget*>(&*d);
+    GenerateTargetsDepthFirst(dependee, remaining);
+    // Take the union of visited source files of custom commands
+    auto visited = GetSourcesVisited(dependee);
+    GetSourcesVisited(target).insert(visited.begin(), visited.end());
+  }
+  if (static_cast<cmGlobalVisualStudioGenerator*>(this->GlobalGenerator)
+        ->TargetIsFortranOnly(target)) {
+    this->CreateSingleVCProj(target->GetName(), target);
+  } else {
+    cmVisualStudio10TargetGenerator tg(
+      target, static_cast<cmGlobalVisualStudio10Generator*>(
+                this->GetGlobalGenerator()));
+    tg.Generate();
+  }
+}
+
 void cmLocalVisualStudio10Generator::Generate()
 {
-  const std::vector<cmGeneratorTarget*>& tgts = this->GetGeneratorTargets();
-  for (cmGeneratorTarget* l : tgts) {
-    if (l->GetType() == cmStateEnums::INTERFACE_LIBRARY) {
-      continue;
-    }
-    if (static_cast<cmGlobalVisualStudioGenerator*>(this->GlobalGenerator)
-          ->TargetIsFortranOnly(l)) {
-      this->CreateSingleVCProj(l->GetName(), l);
-    } else {
-      cmVisualStudio10TargetGenerator tg(
-        l, static_cast<cmGlobalVisualStudio10Generator*>(
-             this->GetGlobalGenerator()));
-      tg.Generate();
+  std::vector<cmGeneratorTarget*> remaining = this->GetGeneratorTargets();
+  for (auto& t : remaining) {
+    if (t) {
+      GenerateTargetsDepthFirst(t, remaining);
     }
   }
   this->WriteStampFiles();