cmTestGenerator,cmInstallGenerator: Factor out BUILD_DEPENDS entry resolution

Move the resolution of a single `BUILD_DEPENDS` entry to a target or file
into a local helper in `cmTestGenerator::EvaluateBuildDependencies` and
`cmInstallGenerator::ResolveBuildDepends`, in preparation for also using
it on values evaluated from generator expressions.  No change in behavior.

Source/cmInstallGenerator.cxx

@@ -288,10 +288,12 @@ bool cmInstallGenerator::ResolveBuildDepends(
                          return gg->FindArtifactOwningTarget(file, config);
                        });
   };
-  for (std::string const& name : names) {
+  // Resolve a name to a target or a file.
+  auto const resolve = [this, lg, gg, &signature, &entries,
+                        &isArtifact](std::string const& name) -> bool {
     if (cmGeneratorTarget const* target = lg->FindGeneratorTargetToUse(name)) {
       entries.Targets.push_back(target);
-      continue;
+      return true;
     }
     // A relative path is interpreted with respect to the current source
     // directory if the file exists there, and otherwise the current binary
@@ -300,13 +302,19 @@ bool cmInstallGenerator::ResolveBuildDepends(
     if (gg->IsGeneratedByBuild(file) || isArtifact(file) ||
         cmSystemTools::FileExists(file)) {
       entries.Files.push_back(std::move(file));
-    } else {
-      lg->IssueMessage(
-        MessageType::FATAL_ERROR,
-        cmStrCat("install(", signature, ") BUILD_DEPENDS entry \"", name,
-                 "\" is neither a target nor a file that exists or is "
-                 "generated by the build."),
-        this->GetBacktrace());
+      return true;
+    }
+    lg->IssueMessage(
+      MessageType::FATAL_ERROR,
+      cmStrCat("install(", signature, ") BUILD_DEPENDS entry \"", name,
+               "\" is neither a target nor a file that exists or is "
+               "generated by the build."),
+      this->GetBacktrace());
+    return false;
+  };
+
+  for (std::string const& name : names) {
+    if (!resolve(name)) {
       return false;
     }
   }

Source/cmTestGenerator.cxx

@@ -132,21 +132,25 @@ bool cmTestGenerator::EvaluateBuildDependencies(
   }
 
   // Add dependencies from BUILD_DEPENDS keyword
-  for (std::string const& depName : buildDepends) {
-    if (depName.empty()) {
-      continue;
-    }
+  cmGlobalGenerator* gg = lg->GetGlobalGenerator();
+  auto addBuildDependency = [lg, gg, &dependencies,
+                             &info](std::string const& depName) {
     cmGeneratorTarget* depTarget = lg->FindGeneratorTargetToUse(depName);
     if (!depTarget) {
-      cmGlobalGenerator* gg = lg->GetGlobalGenerator();
       BuildDependencies::FileDependency file;
       file.Path = lg->GetRealFileDependency(depName);
       file.Owner = gg->FindOutputOwningTarget(file.Path);
       file.Generated = gg->IsGeneratedByBuild(file.Path);
       info.Files.push_back(std::move(file));
-      continue;
+      return;
     }
     dependencies.insert(depTarget);
+  };
+  for (std::string const& depName : buildDepends) {
+    if (depName.empty()) {
+      continue;
+    }
+    addBuildDependency(depName);
   }
 
   for (cmGeneratorTarget* gt : dependencies) {