[PATCH] D51729: [Tooling] JSONCompilationDatabasePlugin infers compile commands for missing files

[Sam McCall via Phabricator via cfe-commits]

sammccall created this revision.
sammccall added a reviewer: bkramer.
Herald added subscribers: cfe-commits, kadircet, ioeric, ilya-biryukov.

See the existing InterpolatingCompilationDatabase for details on how this works.
We've been using this in clangd for a while, the heuristics seem to work well.


Repository:
  rC Clang

https://reviews.llvm.org/D51729

Files:
  lib/Tooling/JSONCompilationDatabase.cpp
  test/Tooling/auto-detect-from-source.cpp


Index: test/Tooling/auto-detect-from-source.cpp
===================================================================
--- test/Tooling/auto-detect-from-source.cpp
+++ test/Tooling/auto-detect-from-source.cpp
@@ -1,8 +1,12 @@
 // RUN: rm -rf %t
 // RUN: mkdir %t
-// RUN: echo "[{\"directory\":\".\",\"command\":\"clang++ -c %/t/test.cpp\",\"file\":\"%/t/test.cpp\"}]" | sed -e 's/\\/\\\\/g' > %t/compile_commands.json
+// RUN: echo "[{\"directory\":\".\",\"command\":\"clang++ -DSECRET=XYZZY -c %/t/test.cpp\",\"file\":\"%/t/test.cpp\"}]" | sed -e 's/\\/\\\\/g' > %t/compile_commands.json
 // RUN: cp "%s" "%t/test.cpp"
 // RUN: not clang-check "%t/test.cpp" 2>&1 | FileCheck %s
 
-// CHECK: C++ requires
-invalid;
+// CHECK: XYZZY
+SECRET;
+
+// Copy to a different file, and rely on the command being inferred.
+// RUN: cp "%s" "%t/other.cpp"
+// RUN: not clang-check "%t/other.cpp" 2>&1 | FileCheck %s
Index: lib/Tooling/JSONCompilationDatabase.cpp
===================================================================
--- lib/Tooling/JSONCompilationDatabase.cpp
+++ lib/Tooling/JSONCompilationDatabase.cpp
@@ -157,13 +157,16 @@
   return parser.parse();
 }
 
+// This plugin locates a nearby compile_command.json file, and also infers
+// compile commands for files not present in the database.
 class JSONCompilationDatabasePlugin : public CompilationDatabasePlugin {
   std::unique_ptr<CompilationDatabase>
   loadFromDirectory(StringRef Directory, std::string &ErrorMessage) override {
     SmallString<1024> JSONDatabasePath(Directory);
     llvm::sys::path::append(JSONDatabasePath, "compile_commands.json");
-    return JSONCompilationDatabase::loadFromFile(
+    auto Base = JSONCompilationDatabase::loadFromFile(
         JSONDatabasePath, ErrorMessage, JSONCommandLineSyntax::AutoDetect);
+    return Base ? inferMissingCompileCommands(std::move(Base)) : nullptr;
   }
 };
 


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