mir/libreoffice
2
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Extend loplugin:passstuffbyref to handle lambdas

Browse Source 
...even if it is known to be dangerous

Change-Id: Ied96284e33b966bf072d0961054479ec7f891dea
This commit is contained in:
Stephan Bergmann
2015-02-05 16:53:30 +01:00
parent 846d340d6a
commit 0a1c6d4554
2 changed files with 57 additions and 29 deletions
Download Patch File Download Diff File Expand all files Collapse all files

84
compilerplugins/clang/passstuffbyref.cxx
View File

@@ -16,6 +16,12 @@
// It's not very efficient, because we generally end up copying it twice - once into the parameter and
// again into the destination.
// They should rather be passed by reference.
//
// Generally recommending lambda capture by-ref rather than by-copy is even more
// problematic than with function parameters, as a lambda instance can easily
// outlive a referrenced variable. So once lambdas start to get used in more
// sophisticated ways than passing them into standard algorithms, this plugin's
// advice, at least for explicit captures, will need to be revisited.
namespace {
@@ -28,6 +34,11 @@ public:
virtual void run() override { TraverseDecl(compiler.getASTContext().getTranslationUnitDecl()); }
bool VisitFunctionDecl(const FunctionDecl * decl);
bool VisitLambdaExpr(const LambdaExpr * expr);
private:
bool isFat(QualType type, std::string * name);
};
bool PassStuffByRef::VisitFunctionDecl(const FunctionDecl * functionDecl) {
@@ -49,41 +60,58 @@ bool PassStuffByRef::VisitFunctionDecl(const FunctionDecl * functionDecl) {
unsigned n = functionDecl->getNumParams();
for (unsigned i = 0; i != n; ++i) {
const ParmVarDecl * pvDecl = functionDecl->getParamDecl(i);
QualType t1 { pvDecl->getType() };
if (!t1->isClassType()) {
continue;
}
string typeName = t1.getUnqualifiedType().getCanonicalType().getAsString();
bool bFound = false;
if (typeName == "class rtl::OUString" ||
typeName == "class rtl::OString" ||
typeName.find("class com::sun::star::uno::Sequence") == 0) {
bFound = true;
}
if (!bFound && !t1->isIncompleteType()) {
const clang::Type* type = t1.getTypePtrOrNull();
if (type != nullptr) {
clang::CharUnits size = compiler.getASTContext().getTypeSizeInChars(type);
if (size.getQuantity() > 64) {
bFound = true;
}
}
}
if (bFound) {
std::string name;
if (isFat(pvDecl->getType(), &name)) {
report(
DiagnosticsEngine::Warning,
"passing " + typeName + " by value, rather pass by reference .e.g. 'const " + typeName + "&'",
pvDecl->getSourceRange().getBegin())
<< pvDecl->getSourceRange();
("passing '%0' by value, rather pass by reference, e.g., '%0"
" const &'"),
pvDecl->getLocation())
<< name << pvDecl->getSourceRange();
}
}
return true;
}
bool PassStuffByRef::VisitLambdaExpr(const LambdaExpr * expr) {
if (ignoreLocation(expr)) {
return true;
}
for (auto const & i: expr->captures()) {
if (i.getCaptureKind() == LambdaCaptureKind::LCK_ByCopy) {
std::string name;
if (isFat(i.getCapturedVar()->getType(), &name)) {
report(
DiagnosticsEngine::Warning,
("%0 capture of '%1' variable by copy, rather use capture"
" by reference---UNLESS THE LAMBDA OUTLIVES THE VARIABLE"),
i.getLocation())
<< (i.isImplicit() ? "implicit" : "explicit") << name
<< expr->getSourceRange();
}
}
}
return true;
}
bool PassStuffByRef::isFat(QualType type, std::string * name) {
if (!type->isClassType()) {
return false;
}
*name = type.getUnqualifiedType().getCanonicalType().getAsString();
if (*name == "class rtl::OUString" || *name == "class rtl::OString"
|| name->find("class com::sun::star::uno::Sequence") == 0)
{
return true;
}
if (type->isIncompleteType()) {
return false;
}
Type const * t2 = type.getTypePtrOrNull();
return t2 != nullptr
&& compiler.getASTContext().getTypeSizeInChars(t2).getQuantity() > 64;
}
loplugin::Plugin::Registration< PassStuffByRef > X("passstuffbyref");
}