1 //===--- ExplicitMakePairCheck.cpp - clang-tidy -----------------*- C++ -*-===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "ExplicitMakePairCheck.h"
11 #include "clang/AST/ASTContext.h"
12 #include "clang/ASTMatchers/ASTMatchFinder.h"
13 #include "clang/ASTMatchers/ASTMatchers.h"
14 
15 using namespace clang::ast_matchers;
16 
17 namespace clang {
18 namespace {
19 AST_MATCHER(DeclRefExpr, hasExplicitTemplateArgs) {
20   return Node.hasExplicitTemplateArgs();
21 }
22 } // namespace
23 
24 namespace tidy {
25 namespace google {
26 namespace build {
27 
28 void ExplicitMakePairCheck::registerMatchers(
29     ast_matchers::MatchFinder *Finder) {
30   // Only register the matchers for C++; the functionality currently does not
31   // provide any benefit to other languages, despite being benign.
32   if (!getLangOpts().CPlusPlus)
33     return;
34 
35   // Look for std::make_pair with explicit template args. Ignore calls in
36   // templates.
37   Finder->addMatcher(
38       callExpr(unless(isInTemplateInstantiation()),
39                callee(expr(ignoringParenImpCasts(
40                    declRefExpr(hasExplicitTemplateArgs(),
41                                to(functionDecl(hasName("::std::make_pair"))))
42                        .bind("declref")))))
43           .bind("call"),
44       this);
45 }
46 
47 void ExplicitMakePairCheck::check(const MatchFinder::MatchResult &Result) {
48   const auto *Call = Result.Nodes.getNodeAs<CallExpr>("call");
49   const auto *DeclRef = Result.Nodes.getNodeAs<DeclRefExpr>("declref");
50 
51   // Sanity check: The use might have overriden ::std::make_pair.
52   if (Call->getNumArgs() != 2)
53     return;
54 
55   const Expr *Arg0 = Call->getArg(0)->IgnoreParenImpCasts();
56   const Expr *Arg1 = Call->getArg(1)->IgnoreParenImpCasts();
57 
58   // If types don't match, we suggest replacing with std::pair and explicit
59   // template arguments. Otherwise just remove the template arguments from
60   // make_pair.
61   if (Arg0->getType() != Call->getArg(0)->getType() ||
62       Arg1->getType() != Call->getArg(1)->getType()) {
63     diag(Call->getLocStart(), "for C++11-compatibility, use pair directly")
64         << FixItHint::CreateReplacement(
65                SourceRange(DeclRef->getLocStart(), DeclRef->getLAngleLoc()),
66                "std::pair<");
67   } else {
68     diag(Call->getLocStart(),
69          "for C++11-compatibility, omit template arguments from make_pair")
70         << FixItHint::CreateRemoval(
71                SourceRange(DeclRef->getLAngleLoc(), DeclRef->getRAngleLoc()));
72   }
73 }
74 
75 } // namespace build
76 } // namespace google
77 } // namespace tidy
78 } // namespace clang
79