1 //===--- IncludeOrderCheck.cpp - clang-tidy -------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include "IncludeOrderCheck.h"
10 #include "clang/Frontend/CompilerInstance.h"
11 #include "clang/Lex/PPCallbacks.h"
12 #include "clang/Lex/Preprocessor.h"
13 
14 #include <map>
15 
16 namespace clang {
17 namespace tidy {
18 namespace llvm_check {
19 
20 namespace {
21 class IncludeOrderPPCallbacks : public PPCallbacks {
22 public:
23   explicit IncludeOrderPPCallbacks(ClangTidyCheck &Check,
24                                    const SourceManager &SM)
25       : LookForMainModule(true), Check(Check), SM(SM) {}
26 
27   void InclusionDirective(SourceLocation HashLoc, const Token &IncludeTok,
28                           StringRef FileName, bool IsAngled,
29                           CharSourceRange FilenameRange, const FileEntry *File,
30                           StringRef SearchPath, StringRef RelativePath,
31                           const Module *Imported,
32                           SrcMgr::CharacteristicKind FileType) override;
33   void EndOfMainFile() override;
34 
35 private:
36   struct IncludeDirective {
37     SourceLocation Loc;    ///< '#' location in the include directive
38     CharSourceRange Range; ///< SourceRange for the file name
39     std::string Filename;  ///< Filename as a string
40     bool IsAngled;         ///< true if this was an include with angle brackets
41     bool IsMainModule;     ///< true if this was the first include in a file
42   };
43 
44   typedef std::vector<IncludeDirective> FileIncludes;
45   std::map<clang::FileID, FileIncludes> IncludeDirectives;
46   bool LookForMainModule;
47 
48   ClangTidyCheck &Check;
49   const SourceManager &SM;
50 };
51 } // namespace
52 
53 void IncludeOrderCheck::registerPPCallbacks(const SourceManager &SM,
54                                             Preprocessor *PP,
55                                             Preprocessor *ModuleExpanderPP) {
56   PP->addPPCallbacks(::std::make_unique<IncludeOrderPPCallbacks>(*this, SM));
57 }
58 
59 static int getPriority(StringRef Filename, bool IsAngled, bool IsMainModule) {
60   // We leave the main module header at the top.
61   if (IsMainModule)
62     return 0;
63 
64   // LLVM and clang headers are in the penultimate position.
65   if (Filename.startswith("llvm/") || Filename.startswith("llvm-c/") ||
66       Filename.startswith("clang/") || Filename.startswith("clang-c/"))
67     return 2;
68 
69   // System headers are sorted to the end.
70   if (IsAngled || Filename.startswith("gtest/") ||
71       Filename.startswith("gmock/"))
72     return 3;
73 
74   // Other headers are inserted between the main module header and LLVM headers.
75   return 1;
76 }
77 
78 void IncludeOrderPPCallbacks::InclusionDirective(
79     SourceLocation HashLoc, const Token &IncludeTok, StringRef FileName,
80     bool IsAngled, CharSourceRange FilenameRange, const FileEntry *File,
81     StringRef SearchPath, StringRef RelativePath, const Module *Imported,
82     SrcMgr::CharacteristicKind FileType) {
83   // We recognize the first include as a special main module header and want
84   // to leave it in the top position.
85   IncludeDirective ID = {HashLoc, FilenameRange, std::string(FileName),
86                          IsAngled, false};
87   if (LookForMainModule && !IsAngled) {
88     ID.IsMainModule = true;
89     LookForMainModule = false;
90   }
91 
92   // Bucket the include directives by the id of the file they were declared in.
93   IncludeDirectives[SM.getFileID(HashLoc)].push_back(std::move(ID));
94 }
95 
96 void IncludeOrderPPCallbacks::EndOfMainFile() {
97   LookForMainModule = true;
98   if (IncludeDirectives.empty())
99     return;
100 
101   // TODO: find duplicated includes.
102 
103   // Form blocks of includes. We don't want to sort across blocks. This also
104   // implicitly makes us never reorder over #defines or #if directives.
105   // FIXME: We should be more careful about sorting below comments as we don't
106   // know if the comment refers to the next include or the whole block that
107   // follows.
108   for (auto &Bucket : IncludeDirectives) {
109     auto &FileDirectives = Bucket.second;
110     std::vector<unsigned> Blocks(1, 0);
111     for (unsigned I = 1, E = FileDirectives.size(); I != E; ++I)
112       if (SM.getExpansionLineNumber(FileDirectives[I].Loc) !=
113           SM.getExpansionLineNumber(FileDirectives[I - 1].Loc) + 1)
114         Blocks.push_back(I);
115     Blocks.push_back(FileDirectives.size()); // Sentinel value.
116 
117     // Get a vector of indices.
118     std::vector<unsigned> IncludeIndices;
119     for (unsigned I = 0, E = FileDirectives.size(); I != E; ++I)
120       IncludeIndices.push_back(I);
121 
122     // Sort the includes. We first sort by priority, then lexicographically.
123     for (unsigned BI = 0, BE = Blocks.size() - 1; BI != BE; ++BI)
124       std::sort(IncludeIndices.begin() + Blocks[BI],
125                 IncludeIndices.begin() + Blocks[BI + 1],
126                 [&FileDirectives](unsigned LHSI, unsigned RHSI) {
127                   IncludeDirective &LHS = FileDirectives[LHSI];
128                   IncludeDirective &RHS = FileDirectives[RHSI];
129 
130                   int PriorityLHS =
131                       getPriority(LHS.Filename, LHS.IsAngled, LHS.IsMainModule);
132                   int PriorityRHS =
133                       getPriority(RHS.Filename, RHS.IsAngled, RHS.IsMainModule);
134 
135                   return std::tie(PriorityLHS, LHS.Filename) <
136                          std::tie(PriorityRHS, RHS.Filename);
137                 });
138 
139     // Emit a warning for each block and fixits for all changes within that
140     // block.
141     for (unsigned BI = 0, BE = Blocks.size() - 1; BI != BE; ++BI) {
142       // Find the first include that's not in the right position.
143       unsigned I, E;
144       for (I = Blocks[BI], E = Blocks[BI + 1]; I != E; ++I)
145         if (IncludeIndices[I] != I)
146           break;
147 
148       if (I == E)
149         continue;
150 
151       // Emit a warning.
152       auto D = Check.diag(FileDirectives[I].Loc,
153                           "#includes are not sorted properly");
154 
155       // Emit fix-its for all following includes in this block.
156       for (; I != E; ++I) {
157         if (IncludeIndices[I] == I)
158           continue;
159         const IncludeDirective &CopyFrom = FileDirectives[IncludeIndices[I]];
160 
161         SourceLocation FromLoc = CopyFrom.Range.getBegin();
162         const char *FromData = SM.getCharacterData(FromLoc);
163         unsigned FromLen = std::strcspn(FromData, "\n");
164 
165         StringRef FixedName(FromData, FromLen);
166 
167         SourceLocation ToLoc = FileDirectives[I].Range.getBegin();
168         const char *ToData = SM.getCharacterData(ToLoc);
169         unsigned ToLen = std::strcspn(ToData, "\n");
170         auto ToRange =
171             CharSourceRange::getCharRange(ToLoc, ToLoc.getLocWithOffset(ToLen));
172 
173         D << FixItHint::CreateReplacement(ToRange, FixedName);
174       }
175     }
176   }
177 
178   IncludeDirectives.clear();
179 }
180 
181 } // namespace llvm_check
182 } // namespace tidy
183 } // namespace clang
184