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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at */
#include "ScopeChecker.h"
#include "CustomMatchers.h"
void ScopeChecker::registerMatchers(MatchFinder *AstMatcher) {
AstMatcher->addMatcher(varDecl().bind("node"), this);
AstMatcher->addMatcher(cxxNewExpr().bind("node"), this);
callExpr(callee(functionDecl(heapAllocator()))).bind("node"), this);
// These enum variants determine whether an allocation has occured in the code.
enum AllocationVariety {
// XXX Currently the Decl* in the AutomaticTemporaryMap is unused, but it
// probably will be used at some point in the future, in order to produce better
// error messages.
typedef DenseMap<const MaterializeTemporaryExpr *, const Decl *>
AutomaticTemporaryMap AutomaticTemporaries;
void ScopeChecker::check(const MatchFinder::MatchResult &Result) {
// There are a variety of different reasons why something could be allocated
AllocationVariety Variety = AV_None;
SourceLocation Loc;
QualType T;
bool IsStaticLocal = false;
if (const ParmVarDecl *D = Result.Nodes.getNodeAs<ParmVarDecl>("node")) {
if (D->hasUnparsedDefaultArg() || D->hasUninstantiatedDefaultArg()) {
if (const Expr *Default = D->getDefaultArg()) {
if (const MaterializeTemporaryExpr *E =
dyn_cast<MaterializeTemporaryExpr>(Default)) {
// We have just found a ParmVarDecl which has, as its default argument,
// a MaterializeTemporaryExpr. We mark that MaterializeTemporaryExpr as
// automatic, by adding it to the AutomaticTemporaryMap.
// Reporting on this type will occur when the MaterializeTemporaryExpr
// is matched against.
AutomaticTemporaries[E] = D;
// Determine the type of allocation which we detected
if (const VarDecl *D = Result.Nodes.getNodeAs<VarDecl>("node")) {
if (D->hasGlobalStorage()) {
Variety = AV_Global;
} else {
Variety = AV_Automatic;
T = D->getType();
Loc = D->getBeginLoc();
IsStaticLocal = D->isStaticLocal();
} else if (const CXXNewExpr *E = Result.Nodes.getNodeAs<CXXNewExpr>("node")) {
// New allocates things on the heap.
// We don't consider placement new to do anything, as it doesn't actually
// allocate the storage, and thus gives us no useful information.
if (!isPlacementNew(E)) {
Variety = AV_Heap;
T = E->getAllocatedType();
Loc = E->getBeginLoc();
} else if (const MaterializeTemporaryExpr *E =
Result.Nodes.getNodeAs<MaterializeTemporaryExpr>("node")) {
// Temporaries can actually have varying storage durations, due to temporary
// lifetime extension. We consider the allocation variety of this temporary
// to be the same as the allocation variety of its lifetime.
// XXX We maybe should mark these lifetimes as being due to a temporary
// which has had its lifetime extended, to improve the error messages.
switch (E->getStorageDuration()) {
case SD_FullExpression: {
// Check if this temporary is allocated as a default argument!
// if it is, we want to pretend that it is automatic.
AutomaticTemporaryMap::iterator AutomaticTemporary =
if (AutomaticTemporary != AutomaticTemporaries.end()) {
Variety = AV_Automatic;
} else {
Variety = AV_Temporary;
} break;
case SD_Automatic:
Variety = AV_Automatic;
case SD_Thread:
case SD_Static:
Variety = AV_Global;
case SD_Dynamic:
assert(false && "I don't think that this ever should occur...");
Variety = AV_Heap;
T = E->getType().getUnqualifiedType();
Loc = E->getBeginLoc();
} else if (const CallExpr *E = Result.Nodes.getNodeAs<CallExpr>("node")) {
T = E->getType()->getPointeeType();
if (!T.isNull()) {
// This will always allocate on the heap, as the heapAllocator() check
// was made in the matcher
Variety = AV_Heap;
Loc = E->getBeginLoc();
// Error messages for incorrect allocations.
const char *Stack = "variable of type %0 only valid on the stack";
const char *Global = "variable of type %0 only valid as global";
const char *Heap = "variable of type %0 only valid on the heap";
const char *NonHeap = "variable of type %0 is not valid on the heap";
const char *NonTemporary = "variable of type %0 is not valid in a temporary";
const char *Temporary = "variable of type %0 is only valid as a temporary";
const char *StaticLocal = "variable of type %0 is only valid as a static "
const char *StackNote =
"value incorrectly allocated in an automatic variable";
const char *GlobalNote = "value incorrectly allocated in a global variable";
const char *HeapNote = "value incorrectly allocated on the heap";
const char *TemporaryNote = "value incorrectly allocated in a temporary";
// Report errors depending on the annotations on the input types.
switch (Variety) {
case AV_None:
case AV_Global:
StackClass.reportErrorIfPresent(*this, T, Loc, Stack, GlobalNote);
HeapClass.reportErrorIfPresent(*this, T, Loc, Heap, GlobalNote);
TemporaryClass.reportErrorIfPresent(*this, T, Loc, Temporary, GlobalNote);
if (!IsStaticLocal) {
StaticLocalClass.reportErrorIfPresent(*this, T, Loc, StaticLocal,
case AV_Automatic:
GlobalClass.reportErrorIfPresent(*this, T, Loc, Global, StackNote);
HeapClass.reportErrorIfPresent(*this, T, Loc, Heap, StackNote);
TemporaryClass.reportErrorIfPresent(*this, T, Loc, Temporary, StackNote);
StaticLocalClass.reportErrorIfPresent(*this, T, Loc, StaticLocal,
case AV_Temporary:
GlobalClass.reportErrorIfPresent(*this, T, Loc, Global, TemporaryNote);
HeapClass.reportErrorIfPresent(*this, T, Loc, Heap, TemporaryNote);
NonTemporaryClass.reportErrorIfPresent(*this, T, Loc, NonTemporary,
StaticLocalClass.reportErrorIfPresent(*this, T, Loc, StaticLocal,
case AV_Heap:
GlobalClass.reportErrorIfPresent(*this, T, Loc, Global, HeapNote);
StackClass.reportErrorIfPresent(*this, T, Loc, Stack, HeapNote);
NonHeapClass.reportErrorIfPresent(*this, T, Loc, NonHeap, HeapNote);
TemporaryClass.reportErrorIfPresent(*this, T, Loc, Temporary, HeapNote);
StaticLocalClass.reportErrorIfPresent(*this, T, Loc, StaticLocal, HeapNote);