[Lex] Fix suggested spelling of /usr/bin/../include/foo

Since D60873 we remove dotdots from the search path entries, but not the
filenames we're matching against, so do the latter too.

Since this also removes (single) dots, drop the logic to skip over them.
(Some of this was already dead, some is newly dead).

See D138676 for motivation.

Differential Revision: https://reviews.llvm.org/D138677

2 files changed, 17 insertions, 17 deletions

diff --git a/clang/lib/Lex/HeaderSearch.cpp b/clang/lib/Lex/HeaderSearch.cpp
index e6af122..0615002 100644
--- a/clang/lib/Lex/HeaderSearch.cpp
+++ b/clang/lib/Lex/HeaderSearch.cpp
@@ -1928,32 +1928,24 @@ std::string HeaderSearch::suggestPathToFileForDiagnostics(
     llvm::StringRef File, llvm::StringRef WorkingDir, llvm::StringRef MainFile,
     bool *IsSystem) {
   using namespace llvm::sys;
+  
+  llvm::SmallString<32> FilePath = File;
+  path::remove_dots(FilePath, /*remove_dot_dot=*/true);
+  File = FilePath;
 
   unsigned BestPrefixLength = 0;
   // Checks whether `Dir` is a strict path prefix of `File`. If so 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());
+  auto CheckDir = [&](llvm::SmallString<32> Dir) -> bool {
     if (!WorkingDir.empty() && !path::is_absolute(Dir))
-      fs::make_absolute(WorkingDir, DirPath);
-    path::remove_dots(DirPath, /*remove_dot_dot=*/true);
-    Dir = DirPath;
+      fs::make_absolute(WorkingDir, Dir);
+    path::remove_dots(Dir, /*remove_dot_dot=*/true);
     for (auto NI = path::begin(File), NE = path::end(File),
               DI = path::begin(Dir), DE = path::end(Dir);
-         /*termination condition in loop*/; ++NI, ++DI) {
-      // '.' components in File are ignored.
-      while (NI != NE && *NI == ".")
-        ++NI;
-      if (NI == NE)
-        break;
-
-      // '.' components in Dir are ignored.
-      while (DI != DE && *DI == ".")
-        ++DI;
+         NI != NE; ++NI, ++DI) {
       if (DI == DE) {
-        // Dir is a prefix of File, up to '.' components and choice of path
-        // separators.
+        // Dir is a prefix of File, up to choice of path separators.
         unsigned PrefixLength = NI - path::begin(File);
         if (PrefixLength > BestPrefixLength) {
           BestPrefixLength = PrefixLength;
diff --git a/clang/unittests/Lex/HeaderSearchTest.cpp b/clang/unittests/Lex/HeaderSearchTest.cpp
index 5024f0d..939f5a7 100644
--- a/clang/unittests/Lex/HeaderSearchTest.cpp
+++ b/clang/unittests/Lex/HeaderSearchTest.cpp
@@ -150,6 +150,14 @@ TEST_F(HeaderSearchTest, DotDotsWithAbsPath) {
             "z");
 }
 
+TEST_F(HeaderSearchTest, BothDotDots) {
+  addSearchDir("/x/../y/");
+  EXPECT_EQ(Search.suggestPathToFileForDiagnostics("/x/../y/z",
+                                                   /*WorkingDir=*/"",
+                                                   /*MainFile=*/""),
+            "z");
+}
+
 TEST_F(HeaderSearchTest, IncludeFromSameDirectory) {
   EXPECT_EQ(Search.suggestPathToFileForDiagnostics("/y/z/t.h",
                                                    /*WorkingDir=*/"",