1 //===--- TransProtectedScope.cpp - Transformations to ARC mode ------------===//
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 // Adds brackets in case statements that "contain" initialization of retaining
11 // variable, thus emitting the "switch case is in protected scope" error.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "Transforms.h"
16 #include "Internals.h"
17 #include "clang/Sema/SemaDiagnostic.h"
18 #include "clang/AST/ASTContext.h"
19 
20 using namespace clang;
21 using namespace arcmt;
22 using namespace trans;
23 
24 namespace {
25 
26 class LocalRefsCollector : public RecursiveASTVisitor<LocalRefsCollector> {
27   SmallVectorImpl<DeclRefExpr *> &Refs;
28 
29 public:
30   LocalRefsCollector(SmallVectorImpl<DeclRefExpr *> &refs)
31     : Refs(refs) { }
32 
33   bool VisitDeclRefExpr(DeclRefExpr *E) {
34     if (ValueDecl *D = E->getDecl())
35       if (D->getDeclContext()->getRedeclContext()->isFunctionOrMethod())
36         Refs.push_back(E);
37     return true;
38   }
39 };
40 
41 struct CaseInfo {
42   SwitchCase *SC;
43   SourceRange Range;
44   enum {
45     St_Unchecked,
46     St_CannotFix,
47     St_Fixed
48   } State;
49 
50   CaseInfo() : SC(0), State(St_Unchecked) {}
51   CaseInfo(SwitchCase *S, SourceRange Range)
52     : SC(S), Range(Range), State(St_Unchecked) {}
53 };
54 
55 class CaseCollector : public RecursiveASTVisitor<CaseCollector> {
56   ParentMap &PMap;
57   llvm::SmallVectorImpl<CaseInfo> &Cases;
58 
59 public:
60   CaseCollector(ParentMap &PMap, llvm::SmallVectorImpl<CaseInfo> &Cases)
61     : PMap(PMap), Cases(Cases) { }
62 
63   bool VisitSwitchStmt(SwitchStmt *S) {
64     SwitchCase *Curr = S->getSwitchCaseList();
65     if (!Curr)
66       return true;
67     Stmt *Parent = getCaseParent(Curr);
68     Curr = Curr->getNextSwitchCase();
69     // Make sure all case statements are in the same scope.
70     while (Curr) {
71       if (getCaseParent(Curr) != Parent)
72         return true;
73       Curr = Curr->getNextSwitchCase();
74     }
75 
76     SourceLocation NextLoc = S->getLocEnd();
77     Curr = S->getSwitchCaseList();
78     // We iterate over case statements in reverse source-order.
79     while (Curr) {
80       Cases.push_back(CaseInfo(Curr,SourceRange(Curr->getLocStart(), NextLoc)));
81       NextLoc = Curr->getLocStart();
82       Curr = Curr->getNextSwitchCase();
83     }
84     return true;
85   }
86 
87   Stmt *getCaseParent(SwitchCase *S) {
88     Stmt *Parent = PMap.getParent(S);
89     while (Parent && (isa<SwitchCase>(Parent) || isa<LabelStmt>(Parent)))
90       Parent = PMap.getParent(Parent);
91     return Parent;
92   }
93 };
94 
95 class ProtectedScopeFixer {
96   MigrationPass &Pass;
97   SourceManager &SM;
98   SmallVector<CaseInfo, 16> Cases;
99   SmallVector<DeclRefExpr *, 16> LocalRefs;
100 
101 public:
102   ProtectedScopeFixer(BodyContext &BodyCtx)
103     : Pass(BodyCtx.getMigrationContext().Pass),
104       SM(Pass.Ctx.getSourceManager()) {
105 
106     CaseCollector(BodyCtx.getParentMap(), Cases)
107         .TraverseStmt(BodyCtx.getTopStmt());
108     LocalRefsCollector(LocalRefs).TraverseStmt(BodyCtx.getTopStmt());
109 
110     SourceRange BodyRange = BodyCtx.getTopStmt()->getSourceRange();
111     const CapturedDiagList &DiagList = Pass.getDiags();
112     CapturedDiagList::iterator I = DiagList.begin(), E = DiagList.end();
113     while (I != E) {
114       if (I->getID() == diag::err_switch_into_protected_scope &&
115           isInRange(I->getLocation(), BodyRange)) {
116         handleProtectedScopeError(I, E);
117         continue;
118       }
119       ++I;
120     }
121   }
122 
123   void handleProtectedScopeError(CapturedDiagList::iterator &DiagI,
124                                  CapturedDiagList::iterator DiagE) {
125     Transaction Trans(Pass.TA);
126     assert(DiagI->getID() == diag::err_switch_into_protected_scope);
127     SourceLocation ErrLoc = DiagI->getLocation();
128     bool handledAllNotes = true;
129     ++DiagI;
130     for (; DiagI != DiagE && DiagI->getLevel() == DiagnosticsEngine::Note;
131          ++DiagI) {
132       if (!handleProtectedNote(*DiagI))
133         handledAllNotes = false;
134     }
135 
136     if (handledAllNotes)
137       Pass.TA.clearDiagnostic(diag::err_switch_into_protected_scope, ErrLoc);
138   }
139 
140   bool handleProtectedNote(const StoredDiagnostic &Diag) {
141     assert(Diag.getLevel() == DiagnosticsEngine::Note);
142 
143     for (unsigned i = 0; i != Cases.size(); i++) {
144       CaseInfo &info = Cases[i];
145       if (isInRange(Diag.getLocation(), info.Range)) {
146 
147         if (info.State == CaseInfo::St_Unchecked)
148           tryFixing(info);
149         assert(info.State != CaseInfo::St_Unchecked);
150 
151         if (info.State == CaseInfo::St_Fixed) {
152           Pass.TA.clearDiagnostic(Diag.getID(), Diag.getLocation());
153           return true;
154         }
155         return false;
156       }
157     }
158 
159     return false;
160   }
161 
162   void tryFixing(CaseInfo &info) {
163     assert(info.State == CaseInfo::St_Unchecked);
164     if (hasVarReferencedOutside(info)) {
165       info.State = CaseInfo::St_CannotFix;
166       return;
167     }
168 
169     Pass.TA.insertAfterToken(info.SC->getColonLoc(), " {");
170     Pass.TA.insert(info.Range.getEnd(), "}\n");
171     info.State = CaseInfo::St_Fixed;
172   }
173 
174   bool hasVarReferencedOutside(CaseInfo &info) {
175     for (unsigned i = 0, e = LocalRefs.size(); i != e; ++i) {
176       DeclRefExpr *DRE = LocalRefs[i];
177       if (isInRange(DRE->getDecl()->getLocation(), info.Range) &&
178           !isInRange(DRE->getLocation(), info.Range))
179         return true;
180     }
181     return false;
182   }
183 
184   bool isInRange(SourceLocation Loc, SourceRange R) {
185     if (Loc.isInvalid())
186       return false;
187     return !SM.isBeforeInTranslationUnit(Loc, R.getBegin()) &&
188             SM.isBeforeInTranslationUnit(Loc, R.getEnd());
189   }
190 };
191 
192 } // anonymous namespace
193 
194 void ProtectedScopeTraverser::traverseBody(BodyContext &BodyCtx) {
195   ProtectedScopeFixer Fix(BodyCtx);
196 }
197