[Tooling] Use FixedCompilationDatabase when `compile_flags.txt` is found.

Summary:
This is an alternative to JSONCompilationDatabase for simple projects that
don't use a build system such as CMake.
(You can also drop one in ~, to make your tools use e.g. C++11 by default)

There's no facility for varying flags per-source-file or per-machine.
Possibly this could be accommodated backwards-compatibly using cpp, but even if
not the simplicity seems worthwhile for the cases that are addressed.

Tested with clangd, works great! (requires clangd restart)

Reviewers: klimek

Subscribers: ilya-biryukov, cfe-commits

Differential Revision: https://reviews.llvm.org/D39799

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@317777 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/docs/JSONCompilationDatabase.rst b/docs/JSONCompilationDatabase.rst
index 8631e8365cead5018c446fad7a8a4e7f710d4988..1f3441b033d40dabbc12614c4ce015ebbedf0940 100644 (file)
--- a/docs/JSONCompilationDatabase.rst
+++ b/docs/JSONCompilationDatabase.rst
@@ -91,3 +91,9 @@ The convention is to name the file compile\_commands.json and put it at
 the top of the build directory. Clang tools are pointed to the top of
 the build directory to detect the file and use the compilation database
 to parse C++ code in the source tree.
+
+Alternatives
+============
+For simple projects, Clang tools also recognize a compile_flags.txt file.
+This should contain one flag per line. The same flags will be used to compile
+any file.

diff --git a/include/clang/Tooling/CompilationDatabase.h b/include/clang/Tooling/CompilationDatabase.h
index 28af33a407dcd9e596c7225bc6e49d962ff17506..e2245798edefe1bb16b3db5e9eec2303aedc801d 100644 (file)
--- a/include/clang/Tooling/CompilationDatabase.h
+++ b/include/clang/Tooling/CompilationDatabase.h
@@ -182,6 +182,11 @@ public:
       int &Argc, const char *const *Argv, std::string &ErrorMsg,
       Twine Directory = ".");
 
+  /// Reads flags from the given file, one-per line.
+  /// Returns nullptr and sets ErrorMessage if we can't read the file.
+  static std::unique_ptr<FixedCompilationDatabase>
+  loadFromFile(StringRef Path, std::string &ErrorMsg);
+
   /// \brief Constructs a compilation data base from a specified directory
   /// and command line.
   FixedCompilationDatabase(Twine Directory, ArrayRef<std::string> CommandLine);

diff --git a/lib/Tooling/CompilationDatabase.cpp b/lib/Tooling/CompilationDatabase.cpp
index 0e835579e04ed871e8c47f0c4423f3d84171a35c..f252ef0b722fd4e2c7993dd8aa726fd6833a8eea 100644 (file)
--- a/lib/Tooling/CompilationDatabase.cpp
+++ b/lib/Tooling/CompilationDatabase.cpp
@@ -10,6 +10,9 @@
 //  This file contains implementations of the CompilationDatabase base class
 //  and the FixedCompilationDatabase.
 //
+//  FIXME: Various functions that take a string &ErrorMessage should be upgraded
+//  to Expected.
+//
 //===----------------------------------------------------------------------===//
 
 #include "clang/Tooling/CompilationDatabase.h"
@@ -26,6 +29,7 @@
 #include "llvm/ADT/SmallString.h"
 #include "llvm/Option/Arg.h"
 #include "llvm/Support/Host.h"
+#include "llvm/Support/LineIterator.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/raw_ostream.h"
 #include <sstream>
@@ -302,8 +306,22 @@ FixedCompilationDatabase::loadFromCommandLine(int &Argc,
   std::vector<std::string> StrippedArgs;
   if (!stripPositionalArgs(CommandLine, StrippedArgs, ErrorMsg))
     return nullptr;
-  return std::unique_ptr<FixedCompilationDatabase>(
-      new FixedCompilationDatabase(Directory, StrippedArgs));
+  return llvm::make_unique<FixedCompilationDatabase>(Directory, StrippedArgs);
+}
+
+std::unique_ptr<FixedCompilationDatabase>
+FixedCompilationDatabase::loadFromFile(StringRef Path, std::string &ErrorMsg) {
+  ErrorMsg.clear();
+  llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> File =
+      llvm::MemoryBuffer::getFile(Path);
+  if (std::error_code Result = File.getError()) {
+    ErrorMsg = "Error while opening fixed database: " + Result.message();
+    return nullptr;
+  }
+  std::vector<std::string> Args{llvm::line_iterator(**File),
+                                llvm::line_iterator()};
+  return llvm::make_unique<FixedCompilationDatabase>(
+      llvm::sys::path::parent_path(Path), std::move(Args));
 }
 
 FixedCompilationDatabase::
@@ -334,6 +352,22 @@ FixedCompilationDatabase::getAllCompileCommands() const {
   return std::vector<CompileCommand>();
 }
 
+namespace {
+
+class FixedCompilationDatabasePlugin : public CompilationDatabasePlugin {
+  std::unique_ptr<CompilationDatabase>
+  loadFromDirectory(StringRef Directory, std::string &ErrorMessage) override {
+    SmallString<1024> DatabasePath(Directory);
+    llvm::sys::path::append(DatabasePath, "compile_flags.txt");
+    return FixedCompilationDatabase::loadFromFile(DatabasePath, ErrorMessage);
+  }
+};
+
+static CompilationDatabasePluginRegistry::Add<FixedCompilationDatabasePlugin>
+X("fixed-compilation-database", "Reads plain-text flags file");
+
+} // namespace
+
 namespace clang {
 namespace tooling {
 

diff --git a/test/Tooling/Inputs/fixed-header.h b/test/Tooling/Inputs/fixed-header.h
new file mode 100644 (file)
index 0000000..4ce318f
--- /dev/null
+++ b/test/Tooling/Inputs/fixed-header.h
@@ -0,0 +1 @@
+#define SECRET_SYMBOL 1

diff --git a/test/Tooling/fixed-database.cpp b/test/Tooling/fixed-database.cpp
new file mode 100644 (file)
index 0000000..e0cdb1e
--- /dev/null
+++ b/test/Tooling/fixed-database.cpp
@@ -0,0 +1,18 @@
+// RUN: rm -rf %t
+// RUN: mkdir -p %t/Src
+// RUN: cp "%s" "%t/Src/test.cpp"
+// RUN: mkdir -p %t/Include
+// RUN: cp "%S/Inputs/fixed-header.h" "%t/Include/"
+// -I flag is relative to %t (where compile_flags is), not Src/.
+// RUN: echo '-IInclude/' >> %t/compile_flags.txt
+// RUN: echo "-Dklazz=class" >> %t/compile_flags.txt
+// RUN: echo '-std=c++11' >> %t/compile_flags.txt
+// RUN: clang-check "%t/Src/test.cpp" 2>&1
+// RUN: not clang-check "%s" 2>&1 | FileCheck "%s" -check-prefix=NODB
+
+// NODB: unknown type name 'klazz'
+klazz F{};
+
+// NODB: 'fixed-header.h' file not found
+#include "fixed-header.h"
+static_assert(SECRET_SYMBOL == 1, "");