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Add a static_assert to enforce that parameters to llvm::format() are not totally unsafe 

Summary:
I had for the second time today a bug where llvm::format("%s", Str)
was called with Str being a StringRef. The Linux and MacOS bots were
fine, but windows having different calling convention, it printed
garbage.

Instead we can catch this at compile-time: it is never expected to
call a C vararg printf-like function with non scalar type I believe.

Reviewers: bogner, Bigcheese, dexonsmith

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D25266

llvm-svn: 283509
This commit is contained in:
Mehdi Amini 2016-10-06 23:26:29 +00:00
parent e15a370084
commit a7e893f638
2 changed files with 15 additions and 2 deletions
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14
llvm/include/llvm/Support/Format.h
View File

@ -75,6 +75,16 @@ public:
/// printed, this synthesizes the string into a temporary buffer provided and
/// returns whether or not it is big enough.
// Helper to validate that format() parameters are scalars or pointers.
template <typename... Args> struct validate_format_parameters;
template <typename Arg, typename... Args>
struct validate_format_parameters<Arg, Args...> {
static_assert(std::is_scalar<Arg>::value,
"format can't be used with non fundamental / non pointer type");
validate_format_parameters() { validate_format_parameters<Args...>(); }
};
template <> struct validate_format_parameters<> {};
template <typename... Ts>
class format_object final : public format_object_base {
std::tuple<Ts...> Vals;
@ -91,7 +101,9 @@ class format_object final : public format_object_base {
public:
format_object(const char *fmt, const Ts &... vals)
: format_object_base(fmt), Vals(vals...) {}
: format_object_base(fmt), Vals(vals...) {
validate_format_parameters<Ts...>();
}
int snprint(char *Buffer, unsigned BufferSize) const override {
return snprint_tuple(Buffer, BufferSize, index_sequence_for<Ts...>());

3
llvm/lib/Target/PowerPC/PPCVSXSwapRemoval.cpp
View File

@ -962,7 +962,8 @@ void PPCVSXSwapRemoval::dumpSwapVector() {
DEBUG(dbgs() << format("%6d", ID));
DEBUG(dbgs() << format("%6d", EC->getLeaderValue(ID)));
DEBUG(dbgs() << format(" BB#%3d", MI->getParent()->getNumber()));
DEBUG(dbgs() << format(" %14s ", TII->getName(MI->getOpcode())));
DEBUG(dbgs() << format(" %14s ",
TII->getName(MI->getOpcode()).str().c_str()));
if (SwapVector[EntryIdx].IsLoad)
DEBUG(dbgs() << "load ");