[clangd] Make config::Provider::combine non-owning. NFC

This is a prerequisite for having ClangdLSPServer inject its own.

Author: sam-mccall

clang-tools-extra/clangd/ConfigProvider.cpp

@@ -193,9 +193,9 @@ Provider::fromAncestorRelativeYAMLFiles(llvm::StringRef RelPath,
 }
 
 std::unique_ptr<Provider>
-Provider::combine(std::vector<std::unique_ptr<Provider>> Providers) {
+Provider::combine(std::vector<const Provider *> Providers) {
   struct CombinedProvider : Provider {
-    std::vector<std::unique_ptr<Provider>> Providers;
+    std::vector<const Provider *> Providers;
 
     std::vector<CompiledFragment>
     getFragments(const Params &P, DiagnosticCallback DC) const override {

clang-tools-extra/clangd/ConfigProvider.h

@@ -76,8 +76,7 @@ class Provider {
 
   /// A provider that includes fragments from all the supplied providers.
   /// Order is preserved; later providers take precedence over earlier ones.
-  static std::unique_ptr<Provider>
-      combine(std::vector<std::unique_ptr<Provider>>);
+  static std::unique_ptr<Provider> combine(std::vector<const Provider *>);
 
   /// Build a config based on this provider.
   Config getConfig(const Params &, DiagnosticCallback) const;

clang-tools-extra/clangd/tool/ClangdMain.cpp

@@ -703,9 +703,9 @@ clangd accepts flags on the commandline, and in the CLANGD_FLAGS environment var
   CCOpts.RunParser = CodeCompletionParse;
 
   RealThreadsafeFS TFS;
+  std::vector<std::unique_ptr<config::Provider>> ProviderStack;
   std::unique_ptr<config::Provider> Config;
   if (EnableConfig) {
-    std::vector<std::unique_ptr<config::Provider>> ProviderStack;
     ProviderStack.push_back(
         config::Provider::fromAncestorRelativeYAMLFiles(".clangd", TFS));
     llvm::SmallString<256> UserConfig;
@@ -716,7 +716,10 @@ clangd accepts flags on the commandline, and in the CLANGD_FLAGS environment var
     } else {
       elog("Couldn't determine user config file, not loading");
     }
-    Config = config::Provider::combine(std::move(ProviderStack));
+    std::vector<const config::Provider *> ProviderPointers;
+    for (const auto& P : ProviderStack)
+      ProviderPointers.push_back(P.get());
+    Config = config::Provider::combine(std::move(ProviderPointers));
     Opts.ConfigProvider = Config.get();
   }
 

clang-tools-extra/clangd/unittests/ConfigProviderTests.cpp

@@ -57,10 +57,9 @@ std::vector<std::string> getAddedArgs(Config &C) {
 // cache their results.
 TEST(ProviderTest, Combine) {
   CapturedDiags Diags;
-  std::vector<std::unique_ptr<Provider>> Providers;
-  Providers.push_back(std::make_unique<FakeProvider>("foo"));
-  Providers.push_back(std::make_unique<FakeProvider>("bar"));
-  auto Combined = Provider::combine(std::move(Providers));
+  FakeProvider Foo("foo");
+  FakeProvider Bar("bar");
+  auto Combined = Provider::combine({&Foo, &Bar});
   Config Cfg = Combined->getConfig(Params(), Diags.callback());
   EXPECT_THAT(Diags.Diagnostics,
               ElementsAre(DiagMessage("foo"), DiagMessage("bar")));