[clangd] Always try to build absolute path

[kadircet]

Summary

This only changes behavior in cases when the file itself is a symlink.

When canonicalizing paths do not look at tryGetRealPathName, which
contains the resolved path for files that are symlinks. Instead first build the
absolute path even if it contains some symlinks on the path. Then resolve only
the symlinks on the path and leave it as it is if the file itself is a symlink.

[ilya-biryukov]

LGTM
NIT: a typo in the change description: s/smylinks/symlinks

Maybe also add a separate sentence to the description that this should not affect the behavior if file is not a symlink, e.g. something like

This only changes behavior in cases when the file itself is a symlink.

This information is present in the change description, but a little hard to find.

clang-tools-extra/trunk/clangd/SourceCode.cpp

for (const auto &R : Repls)
     Edits.push_back(replacementToEdit(Code, R));
   return Edits;
 }
 
 Optional<std::string> getCanonicalPath(const FileEntry *F,
                                        const SourceManager &SourceMgr) {
   if (!F)
     return None;
-  // Ideally, we get the real path from the FileEntry object.
-  SmallString<128> FilePath = F->tryGetRealPathName();
-  if (!FilePath.empty() && sys::path::is_absolute(FilePath))
-    return FilePath.str().str();
-
-  // Otherwise, we try to compute ourselves.
-  FilePath = F->getName();
-  vlog("FileEntry for {0} did not contain the real path.", FilePath);
 
+  SmallString<128> FilePath = F->getName();
   if (!sys::path::is_absolute(FilePath)) {
     if (auto EC =
             SourceMgr.getFileManager().getVirtualFileSystem()->makeAbsolute(
                 FilePath)) {
       elog("Could not turn relative path '{0}' to absolute: {1}", FilePath,
            EC.message());
       return None;
     }