[clang-format] support header deletion in cleanupAroundReplacemnts.

Summary:
- If a replacement has offset UINT_MAX, length 0, and a replacement text
  that is an #include directive, this will insert the #include into the
  correct block in the \p Code.
- If a replacement has offset UINT_MAX, length 1, and a replacement text
  that is the name of the header to be removed, the header will be removed
  from \p Code if it exists.

Reviewers: djasper

Subscribers: cfe-commits, klimek

Differential Revision: https://reviews.llvm.org/D24829

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@282253 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 93 insertions, 6 deletions

diff --git a/include/clang/Format/Format.h b/include/clang/Format/Format.h
index 858989182b..ac1c9687ad 100644
--- a/include/clang/Format/Format.h
+++ b/include/clang/Format/Format.h
@@ -783,8 +783,13 @@ formatReplacements(StringRef Code, const tooling::Replacements &Replaces,
 /// \brief Returns the replacements corresponding to applying \p Replaces and
 /// cleaning up the code after that on success; otherwise, return an llvm::Error
 /// carrying llvm::StringError.
-/// This also inserts a C++ #include directive into the correct block if the
-/// replacement corresponding to the header insertion has offset UINT_MAX.
+/// This also supports inserting/deleting C++ #include directives:
+/// - If a replacement has offset UINT_MAX, length 0, and a replacement text
+///   that is an #include directive, this will insert the #include into the
+///   correct block in the \p Code.
+/// - If a replacement has offset UINT_MAX, length 1, and a replacement text
+///   that is the name of the header to be removed, the header will be removed
+///   from \p Code if it exists.
 llvm::Expected<tooling::Replacements>
 cleanupAroundReplacements(StringRef Code, const tooling::Replacements &Replaces,
                           const FormatStyle &Style);
diff --git a/lib/Format/Format.cpp b/lib/Format/Format.cpp
index d799eb2e82..4fd6c2a8d7 100644
--- a/lib/Format/Format.cpp
+++ b/lib/Format/Format.cpp
@@ -1504,10 +1504,14 @@ formatReplacements(StringRef Code, const tooling::Replacements &Replaces,
 namespace {
 
 inline bool isHeaderInsertion(const tooling::Replacement &Replace) {
-  return Replace.getOffset() == UINT_MAX &&
+  return Replace.getOffset() == UINT_MAX && Replace.getLength() == 0 &&
          llvm::Regex(IncludeRegexPattern).match(Replace.getReplacementText());
 }
 
+inline bool isHeaderDeletion(const tooling::Replacement &Replace) {
+  return Replace.getOffset() == UINT_MAX && Replace.getLength() == 1;
+}
+
 void skipComments(Lexer &Lex, Token &Tok) {
   while (Tok.is(tok::comment))
     if (Lex.LexFromRawLexer(Tok))
@@ -1548,6 +1552,12 @@ unsigned getOffsetAfterHeaderGuardsAndComments(StringRef FileName,
   return AfterComments;
 }
 
+bool isDeletedHeader(llvm::StringRef HeaderName,
+                     const std::set<llvm::StringRef> HeadersToDelete) {
+  return HeadersToDelete.find(HeaderName) != HeadersToDelete.end() ||
+         HeadersToDelete.find(HeaderName.trim("\"<>")) != HeadersToDelete.end();
+}
+
 // FIXME: we also need to insert a '\n' at the end of the code if we have an
 // insertion with offset Code.size(), and there is no '\n' at the end of the
 // code.
@@ -1561,12 +1571,15 @@ fixCppIncludeInsertions(StringRef Code, const tooling::Replacements &Replaces,
     return Replaces;
 
   tooling::Replacements HeaderInsertions;
+  std::set<llvm::StringRef> HeadersToDelete;
   tooling::Replacements Result;
   for (const auto &R : Replaces) {
     if (isHeaderInsertion(R)) {
       // Replacements from \p Replaces must be conflict-free already, so we can
       // simply consume the error.
       llvm::consumeError(HeaderInsertions.add(R));
+    } else if (isHeaderDeletion(R)) {
+      HeadersToDelete.insert(R.getReplacementText());
     } else if (R.getOffset() == UINT_MAX) {
       llvm::errs() << "Insertions other than header #include insertion are "
                       "not supported! "
@@ -1575,7 +1588,7 @@ fixCppIncludeInsertions(StringRef Code, const tooling::Replacements &Replaces,
       llvm::consumeError(Result.add(R));
     }
   }
-  if (HeaderInsertions.empty())
+  if (HeaderInsertions.empty() && HeadersToDelete.empty())
     return Replaces;
 
   llvm::Regex IncludeRegex(IncludeRegexPattern);
@@ -1605,6 +1618,7 @@ fixCppIncludeInsertions(StringRef Code, const tooling::Replacements &Replaces,
   for (auto Line : Lines) {
     NextLineOffset = std::min(Code.size(), Offset + Line.size() + 1);
     if (IncludeRegex.match(Line, &Matches)) {
+      // The header name with quotes or angle brackets.
       StringRef IncludeName = Matches[2];
       ExistingIncludes.insert(IncludeName);
       int Category = Categories.getIncludePriority(
@@ -1612,6 +1626,19 @@ fixCppIncludeInsertions(StringRef Code, const tooling::Replacements &Replaces,
       CategoryEndOffsets[Category] = NextLineOffset;
       if (FirstIncludeOffset < 0)
         FirstIncludeOffset = Offset;
+      if (isDeletedHeader(IncludeName, HeadersToDelete)) {
+        // If this is the last line without trailing newline, we need to make
+        // sure we don't delete across the file boundary.
+        unsigned Length = std::min(Line.size() + 1, Code.size() - Offset);
+        llvm::Error Err =
+            Result.add(tooling::Replacement(FileName, Offset, Length, ""));
+        if (Err) {
+          // Ignore the deletion on conflict.
+          llvm::errs() << "Failed to add header deletion replacement for "
+                       << IncludeName << ": " << llvm::toString(std::move(Err))
+                       << "\n";
+        }
+      }
     }
     Offset = NextLineOffset;
   }
diff --git a/unittests/Format/CleanupTest.cpp b/unittests/Format/CleanupTest.cpp
index 6072b226e4..c3e297f797 100644
--- a/unittests/Format/CleanupTest.cpp
+++ b/unittests/Format/CleanupTest.cpp
@@ -247,8 +247,12 @@ protected:
     return tooling::Replacement(FileName, Offset, Length, Text);
   }
 
-  tooling::Replacement createInsertion(StringRef HeaderName) {
-    return createReplacement(UINT_MAX, 0, HeaderName);
+  tooling::Replacement createInsertion(StringRef IncludeDirective) {
+    return createReplacement(UINT_MAX, 0, IncludeDirective);
+  }
+
+  tooling::Replacement createDeletion(StringRef HeaderName) {
+    return createReplacement(UINT_MAX, 1, HeaderName);
   }
 
   inline std::string apply(StringRef Code,
@@ -740,6 +744,57 @@ TEST_F(CleanUpReplacementsTest, AddIncludesWithDifferentForms) {
   EXPECT_EQ(Expected, apply(Code, Replaces));
 }
 
+TEST_F(CleanUpReplacementsTest, SimpleDeleteIncludes) {
+  std::string Code = "#include \"abc.h\"\n"
+                     "#include \"xyz.h\" // comment\n"
+                     "#include \"xyz\"\n"
+                     "int x;\n";
+  std::string Expected = "#include \"xyz\"\n"
+                         "int x;\n";
+  tooling::Replacements Replaces =
+      toReplacements({createDeletion("abc.h"), createDeletion("xyz.h")});
+  EXPECT_EQ(Expected, apply(Code, Replaces));
+}
+
+TEST_F(CleanUpReplacementsTest, DeleteAllCode) {
+  std::string Code = "#include \"xyz.h\"\n"
+                     "#include <xyz.h>";
+  std::string Expected = "";
+  tooling::Replacements Replaces = toReplacements({createDeletion("xyz.h")});
+  EXPECT_EQ(Expected, apply(Code, Replaces));
+}
+
+TEST_F(CleanUpReplacementsTest, DeleteAllIncludesWithSameNameIfNoType) {
+  std::string Code = "#include \"xyz.h\"\n"
+                     "#include \"xyz\"\n"
+                     "#include <xyz.h>\n";
+  std::string Expected = "#include \"xyz\"\n";
+  tooling::Replacements Replaces = toReplacements({createDeletion("xyz.h")});
+  EXPECT_EQ(Expected, apply(Code, Replaces));
+}
+
+TEST_F(CleanUpReplacementsTest, OnlyDeleteHeaderWithType) {
+  std::string Code = "#include \"xyz.h\"\n"
+                     "#include \"xyz\"\n"
+                     "#include <xyz.h>";
+  std::string Expected = "#include \"xyz.h\"\n"
+                         "#include \"xyz\"\n";
+  tooling::Replacements Replaces = toReplacements({createDeletion("<xyz.h>")});
+  EXPECT_EQ(Expected, apply(Code, Replaces));
+}
+
+TEST_F(CleanUpReplacementsTest, InsertionAndDeleteHeader) {
+  std::string Code = "#include \"a.h\"\n"
+                     "\n"
+                     "#include <vector>\n";
+  std::string Expected = "#include \"a.h\"\n"
+                         "\n"
+                         "#include <map>\n";
+  tooling::Replacements Replaces = toReplacements(
+      {createDeletion("<vector>"), createInsertion("#include <map>")});
+  EXPECT_EQ(Expected, apply(Code, Replaces));
+}
+
 } // end namespace
 } // end namespace format
 } // end namespace clang