[clang][HeaderSearch] Shorten paths for includes in mainfile's directory

Summary:
Currently HeaderSearch only looks at SearchDir's passed into it, but in
addition to those paths headers can be relative to including file's directory.

This patch makes sure that is taken into account.

Reviewers: gribozavr

Subscribers: jkorous, arphaman, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D63295

llvm-svn: 365005

1 files changed, 28 insertions, 16 deletions

diff --git a/clang/lib/Lex/HeaderSearch.cpp b/clang/lib/Lex/HeaderSearch.cpp
index 3ad0e1e5e83..ca94883ebec 100644
--- a/clang/lib/Lex/HeaderSearch.cpp
+++ b/clang/lib/Lex/HeaderSearch.cpp
@@ -1665,28 +1665,25 @@ void HeaderSearch::loadSubdirectoryModuleMaps(DirectoryLookup &SearchDir) {
   SearchDir.setSearchedAllModuleMaps(true);
 }
 
-std::string HeaderSearch::suggestPathToFileForDiagnostics(const FileEntry *File,
-                                                          bool *IsSystem) {
+std::string HeaderSearch::suggestPathToFileForDiagnostics(
+    const FileEntry *File, llvm::StringRef MainFile, bool *IsSystem) {
   // FIXME: We assume that the path name currently cached in the FileEntry is
   // the most appropriate one for this analysis (and that it's spelled the
   // same way as the corresponding header search path).
-  return suggestPathToFileForDiagnostics(File->getName(), /*BuildDir=*/"",
-                                         IsSystem);
+  return suggestPathToFileForDiagnostics(File->getName(), /*WorkingDir=*/"",
+                                         MainFile, IsSystem);
 }
 
 std::string HeaderSearch::suggestPathToFileForDiagnostics(
-    llvm::StringRef File, llvm::StringRef WorkingDir, bool *IsSystem) {
+    llvm::StringRef File, llvm::StringRef WorkingDir, llvm::StringRef MainFile,
+    bool *IsSystem) {
   using namespace llvm::sys;
 
   unsigned BestPrefixLength = 0;
-  unsigned BestSearchDir;
-
-  for (unsigned I = 0; I != SearchDirs.size(); ++I) {
-    // FIXME: Support this search within frameworks and header maps.
-    if (!SearchDirs[I].isNormalDir())
-      continue;
-
-    StringRef Dir = SearchDirs[I].getDir()->getName();
+  // Checks whether Dir and File shares a common prefix, if they do and that's
+  // the longest prefix we've seen so for it returns true and updates the
+  // BestPrefixLength accordingly.
+  auto CheckDir = [&](llvm::StringRef Dir) -> bool {
     llvm::SmallString<32> DirPath(Dir.begin(), Dir.end());
     if (!WorkingDir.empty() && !path::is_absolute(Dir))
       fs::make_absolute(WorkingDir, DirPath);
@@ -1710,7 +1707,7 @@ std::string HeaderSearch::suggestPathToFileForDiagnostics(
         unsigned PrefixLength = NI - path::begin(File);
         if (PrefixLength > BestPrefixLength) {
           BestPrefixLength = PrefixLength;
-          BestSearchDir = I;
+          return true;
         }
         break;
       }
@@ -1723,9 +1720,24 @@ std::string HeaderSearch::suggestPathToFileForDiagnostics(
       if (*NI != *DI)
         break;
     }
+    return false;
+  };
+
+  for (unsigned I = 0; I != SearchDirs.size(); ++I) {
+    // FIXME: Support this search within frameworks and header maps.
+    if (!SearchDirs[I].isNormalDir())
+      continue;
+
+    StringRef Dir = SearchDirs[I].getDir()->getName();
+    if (CheckDir(Dir) && IsSystem)
+      *IsSystem = BestPrefixLength ? I >= SystemDirIdx : false;
   }
 
-  if (IsSystem)
-    *IsSystem = BestPrefixLength ? BestSearchDir >= SystemDirIdx : false;
+  // Try to shorten include path using TUs directory, if we couldn't find any
+  // suitable prefix in include search paths.
+  if (!BestPrefixLength && CheckDir(path::parent_path(MainFile)) && IsSystem)
+    *IsSystem = false;
+
+
   return path::convert_to_slash(File.drop_front(BestPrefixLength));
 }