NoQ created this revision.
NoQ added reviewers: jkorous, t-rasmud, ziqingluo-90, malavikasamak,
aaron.ballman, gribozavr, ymandel, sgatev.
Herald added subscribers: steakhal, martong.
Herald added a project: All.
NoQ requested review of this revision.
Herald added a subscriber: MaskRay.
This patch implements a new clang driver flag `-fsafe-buffer-usage-suggestions`
which allows turning the smart suggestion machine on and off (defaults to off).
This is valuable for stability reasons, as the machine is being rapidly
improved and we don't want accidental breakages to ruin the build for innocent
users. It is also arguably useful in general because it enables separation of
concerns between project contributors: some users will actively update the code
to conform to the programming model, while others simply want to make sure that
they aren't regressing it. Finally, there could be other valid reasons to opt
out of suggestions entirely on some codebases (while continuing to enforce
`-Wunsafe-buffer-usage` warnings), such as lack of access to hardened libc++
(or even to the C++ standard library in general) on the target platform.
When the flag is disabled, the unsafe buffer usage analysis is reduced to an
extremely minimal mode of operation that contains virtually no smarts: not only
it doesn't offer automatic fixits, but also textual suggestions such as "change
the type of this variable to `std::span` to preserve bounds information" are
not displayed*, and in fact the machine doesn't even try to blame specific
variables in the first place, it simply warns on the operations and leaves
everything else to the user. So this flag turns off a lot more of our complex
machinery than what we already turn off in presence of say
`-fno-diagnostic-fixit-info`.
The flag is discoverable: when it's off, the warnings are accompanied by a
`note:` telling the user that there's a flag they can use. (Do we really need
that? Maybe we should somehow throttle it to reduce noise?)
Repository:
rC Clang
https://reviews.llvm.org/D146669
Files:
clang/include/clang/Analysis/Analyses/UnsafeBufferUsage.h
clang/include/clang/Basic/DiagnosticOptions.def
clang/include/clang/Basic/DiagnosticSemaKinds.td
clang/include/clang/Driver/Options.td
clang/lib/Analysis/UnsafeBufferUsage.cpp
clang/lib/Driver/ToolChains/Clang.cpp
clang/lib/Sema/AnalysisBasedWarnings.cpp
clang/test/SemaCXX/unsafe-buffer-usage-diag-type.cpp
clang/test/SemaCXX/warn-unsafe-buffer-usage-fixits-assign-to-array-subscr-on-ptr.cpp
clang/test/SemaCXX/warn-unsafe-buffer-usage-fixits-deref-simple-ptr-arith.cpp
clang/test/SemaCXX/warn-unsafe-buffer-usage-fixits-local-var-span.cpp
clang/test/SemaCXX/warn-unsafe-buffer-usage-function-attr.cpp
clang/test/SemaCXX/warn-unsafe-buffer-usage-pragma-fixit.cpp
clang/test/SemaCXX/warn-unsafe-buffer-usage-pragma.cpp
clang/test/SemaCXX/warn-unsafe-buffer-usage-suggestions-flag.cpp
clang/test/SemaCXX/warn-unsafe-buffer-usage.cpp
Index: clang/test/SemaCXX/warn-unsafe-buffer-usage.cpp
===================================================================
--- clang/test/SemaCXX/warn-unsafe-buffer-usage.cpp
+++ clang/test/SemaCXX/warn-unsafe-buffer-usage.cpp
@@ -1,4 +1,6 @@
-// RUN: %clang_cc1 -std=c++20 -Wno-all -Wunsafe-buffer-usage -fblocks -include %s -verify %s
+// RUN: %clang_cc1 -std=c++20 -Wno-all -Wunsafe-buffer-usage \
+// RUN: -fsafe-buffer-usage-suggestions \
+// RUN: -fblocks -include %s -verify %s
// RUN: %clang -x c++ -fsyntax-only -fblocks -include %s %s 2>&1 | FileCheck --allow-empty %s
// RUN: %clang_cc1 -std=c++11 -fblocks -include %s %s 2>&1 | FileCheck --allow-empty %s
Index: clang/test/SemaCXX/warn-unsafe-buffer-usage-suggestions-flag.cpp
===================================================================
--- /dev/null
+++ clang/test/SemaCXX/warn-unsafe-buffer-usage-suggestions-flag.cpp
@@ -0,0 +1,54 @@
+// Test the -cc1 flag. There's no -fno-... option in -cc1 invocations,
+// just the positive option.
+
+// RUN: %clang_cc1 -std=c++20 -Wunsafe-buffer-usage -verify=OFF %s
+// RUN: %clang_cc1 -std=c++20 -Wunsafe-buffer-usage -verify=ON %s \
+// RUN: -fsafe-buffer-usage-suggestions
+
+// Test driver flags. Now there's both -f... and -fno-... to worry about.
+
+// RUN: %clang -fsyntax-only -std=c++20 -Wunsafe-buffer-usage \
+// RUN: -Xclang -verify=OFF %s
+// RUN: %clang -fsyntax-only -std=c++20 -Wunsafe-buffer-usage \
+// RUN: -fsafe-buffer-usage-suggestions \
+// RUN: -Xclang -verify=ON %s
+// RUN: %clang -fsyntax-only -std=c++20 -Wunsafe-buffer-usage \
+// RUN: -fno-safe-buffer-usage-suggestions \
+// RUN: -Xclang -verify=OFF %s
+
+// In case of driver flags, last flag takes precedence.
+
+// RUN: %clang -fsyntax-only -std=c++20 -Wunsafe-buffer-usage \
+// RUN: -fsafe-buffer-usage-suggestions \
+// RUN: -fno-safe-buffer-usage-suggestions \
+// RUN: -Xclang -verify=OFF %s
+// RUN: %clang -fsyntax-only -std=c++20 -Wunsafe-buffer-usage \
+// RUN: -fno-safe-buffer-usage-suggestions \
+// RUN: -fsafe-buffer-usage-suggestions \
+// RUN: -Xclang -verify=ON %s
+
+// Passing through -Xclang.
+
+// RUN: %clang -fsyntax-only -std=c++20 -Wunsafe-buffer-usage \
+// RUN: -Xclang -fsafe-buffer-usage-suggestions \
+// RUN: -Xclang -verify=ON %s
+
+// -Xclang flags take precedence over driver flags.
+
+// RUN: %clang -fsyntax-only -std=c++20 -Wunsafe-buffer-usage \
+// RUN: -Xclang -fsafe-buffer-usage-suggestions \
+// RUN: -fno-safe-buffer-usage-suggestions \
+// RUN: -Xclang -verify=ON %s
+// RUN: %clang -fsyntax-only -std=c++20 -Wunsafe-buffer-usage \
+// RUN: -fno-safe-buffer-usage-suggestions \
+// RUN: -Xclang -fsafe-buffer-usage-suggestions \
+// RUN: -Xclang -verify=ON %s
+
+void foo(int *x) { // \
+ // ON-warning{{'x' is an unsafe pointer used for buffer access}}
+ // FIXME: Better "OFF" warning?
+ x[5] = 10; // \
+ // ON-note {{used in buffer access here}} \
+ // OFF-warning{{unsafe buffer access}} \
+ // OFF-note {{pass -fsafe-buffer-usage-suggestions to receive code hardening suggestions}}
+}
Index: clang/test/SemaCXX/warn-unsafe-buffer-usage-pragma.cpp
===================================================================
--- clang/test/SemaCXX/warn-unsafe-buffer-usage-pragma.cpp
+++ clang/test/SemaCXX/warn-unsafe-buffer-usage-pragma.cpp
@@ -1,4 +1,6 @@
-// RUN: %clang_cc1 -std=c++20 -Wunsafe-buffer-usage -Wno-unused-value -verify %s
+// RUN: %clang_cc1 -std=c++20 -Wunsafe-buffer-usage \
+// RUN: -fsafe-buffer-usage-suggestions \
+// RUN: -Wno-unused-value -verify %s
void basic(int * x) { // expected-warning{{'x' is an unsafe pointer used for buffer access}}
int *p1 = new int[10]; // not to warn
Index: clang/test/SemaCXX/warn-unsafe-buffer-usage-pragma-fixit.cpp
===================================================================
--- clang/test/SemaCXX/warn-unsafe-buffer-usage-pragma-fixit.cpp
+++ clang/test/SemaCXX/warn-unsafe-buffer-usage-pragma-fixit.cpp
@@ -1,4 +1,6 @@
-// RUN: %clang_cc1 -std=c++20 -Wunsafe-buffer-usage -fdiagnostics-parseable-fixits %s 2>&1 | FileCheck %s
+// RUN: %clang_cc1 -std=c++20 -Wunsafe-buffer-usage \
+// RUN: -fsafe-buffer-usage-suggestions \
+// RUN: -fdiagnostics-parseable-fixits %s 2>&1 | FileCheck %s
void basic(int * x) {
int tmp;
Index: clang/test/SemaCXX/warn-unsafe-buffer-usage-function-attr.cpp
===================================================================
--- clang/test/SemaCXX/warn-unsafe-buffer-usage-function-attr.cpp
+++ clang/test/SemaCXX/warn-unsafe-buffer-usage-function-attr.cpp
@@ -1,4 +1,5 @@
-// RUN: %clang_cc1 -std=c++20 -Wunsafe-buffer-usage -verify %s
+// RUN: %clang_cc1 -std=c++20 -Wunsafe-buffer-usage \
+// RUN: -fsafe-buffer-usage-suggestions -verify %s
[[clang::unsafe_buffer_usage]]
void deprecatedFunction3();
Index: clang/test/SemaCXX/warn-unsafe-buffer-usage-fixits-local-var-span.cpp
===================================================================
--- clang/test/SemaCXX/warn-unsafe-buffer-usage-fixits-local-var-span.cpp
+++ clang/test/SemaCXX/warn-unsafe-buffer-usage-fixits-local-var-span.cpp
@@ -1,4 +1,6 @@
-// RUN: %clang_cc1 -std=c++20 -Wunsafe-buffer-usage -fdiagnostics-parseable-fixits %s 2>&1 | FileCheck %s
+// RUN: %clang_cc1 -std=c++20 -Wunsafe-buffer-usage \
+// RUN: -fsafe-buffer-usage-suggestions \
+// RUN: -fdiagnostics-parseable-fixits %s 2>&1 | FileCheck %s
typedef int * Int_ptr_t;
typedef int Int_t;
Index: clang/test/SemaCXX/warn-unsafe-buffer-usage-fixits-deref-simple-ptr-arith.cpp
===================================================================
--- clang/test/SemaCXX/warn-unsafe-buffer-usage-fixits-deref-simple-ptr-arith.cpp
+++ clang/test/SemaCXX/warn-unsafe-buffer-usage-fixits-deref-simple-ptr-arith.cpp
@@ -1,4 +1,7 @@
-// RUN: %clang_cc1 -std=c++20 -Wunsafe-buffer-usage -fdiagnostics-parseable-fixits -fsyntax-only %s 2>&1 | FileCheck %s
+// RUN: %clang_cc1 -std=c++20 -Wunsafe-buffer-usage \
+// RUN: -fsafe-buffer-usage-suggestions \
+// RUN: -fdiagnostics-parseable-fixits -fsyntax-only \
+// RUN: %s 2>&1 | FileCheck %s
// TODO test we don't mess up vertical whitespace
// TODO test different whitespaces
Index: clang/test/SemaCXX/warn-unsafe-buffer-usage-fixits-assign-to-array-subscr-on-ptr.cpp
===================================================================
--- clang/test/SemaCXX/warn-unsafe-buffer-usage-fixits-assign-to-array-subscr-on-ptr.cpp
+++ clang/test/SemaCXX/warn-unsafe-buffer-usage-fixits-assign-to-array-subscr-on-ptr.cpp
@@ -1,4 +1,6 @@
-// RUN: %clang_cc1 -std=c++20 -Wunsafe-buffer-usage -fdiagnostics-parseable-fixits %s 2>&1 | FileCheck %s
+// RUN: %clang_cc1 -std=c++20 -Wunsafe-buffer-usage \
+// RUN: -fsafe-buffer-usage-suggestions \
+// RUN: -fdiagnostics-parseable-fixits %s 2>&1 | FileCheck %s
// TODO cases where we don't want fixits
Index: clang/test/SemaCXX/unsafe-buffer-usage-diag-type.cpp
===================================================================
--- clang/test/SemaCXX/unsafe-buffer-usage-diag-type.cpp
+++ clang/test/SemaCXX/unsafe-buffer-usage-diag-type.cpp
@@ -1,4 +1,5 @@
-// RUN: %clang_cc1 -std=c++20 -Wno-all -Wunsafe-buffer-usage -verify %s
+// RUN: %clang_cc1 -std=c++20 -Wno-all -Wunsafe-buffer-usage \
+// RUN: -fsafe-buffer-usage-suggestions -verify %s
namespace localVar {
void testRefersPtrLocalVarDecl(int i) {
Index: clang/lib/Sema/AnalysisBasedWarnings.cpp
===================================================================
--- clang/lib/Sema/AnalysisBasedWarnings.cpp
+++ clang/lib/Sema/AnalysisBasedWarnings.cpp
@@ -2156,9 +2156,11 @@
namespace {
class UnsafeBufferUsageReporter : public UnsafeBufferUsageHandler {
Sema &S;
+ bool SuggestSuggestions;
public:
- UnsafeBufferUsageReporter(Sema &S) : S(S) {}
+ UnsafeBufferUsageReporter(Sema &S, bool SuggestSuggestions)
+ : S(S), SuggestSuggestions(SuggestSuggestions) {}
void handleUnsafeOperation(const Stmt *Operation,
bool IsRelatedToDecl) override {
@@ -2197,10 +2199,14 @@
Loc = Operation->getBeginLoc();
Range = Operation->getSourceRange();
}
- if (IsRelatedToDecl)
+ if (IsRelatedToDecl) {
S.Diag(Loc, diag::note_unsafe_buffer_operation) << MsgParam << Range;
- else
+ } else {
S.Diag(Loc, diag::warn_unsafe_buffer_operation) << MsgParam << Range;
+ if (SuggestSuggestions) {
+ S.Diag(Loc, diag::note_safe_buffer_usage_suggestions_disabled);
+ }
+ }
}
// FIXME: rename to handleUnsafeVariable
@@ -2521,11 +2527,12 @@
// Emit unsafe buffer usage warnings and fixits.
if (!Diags.isIgnored(diag::warn_unsafe_buffer_operation, D->getBeginLoc()) ||
!Diags.isIgnored(diag::warn_unsafe_buffer_variable, D->getBeginLoc())) {
- UnsafeBufferUsageReporter R(S);
- checkUnsafeBufferUsage(
- D, R,
- /*EmitFixits=*/S.getDiagnostics().getDiagnosticOptions().ShowFixits &&
- S.getLangOpts().CPlusPlus20);
+ DiagnosticOptions &DiagOpts = S.getDiagnostics().getDiagnosticOptions();
+ bool EmitSuggestions = DiagOpts.ShowSafeBufferUsageSuggestions &&
+ S.getLangOpts().CPlusPlus20;
+ bool EmitFixits = EmitSuggestions && DiagOpts.ShowFixits;
+ UnsafeBufferUsageReporter R(S, /*SuggestSuggestions=*/!EmitSuggestions);
+ checkUnsafeBufferUsage(D, R, EmitSuggestions, EmitFixits);
}
// If none of the previous checks caused a CFG build, trigger one here
Index: clang/lib/Driver/ToolChains/Clang.cpp
===================================================================
--- clang/lib/Driver/ToolChains/Clang.cpp
+++ clang/lib/Driver/ToolChains/Clang.cpp
@@ -7021,6 +7021,9 @@
A->claim();
}
+ Args.addOptInFlag(CmdArgs, options::OPT_fsafe_buffer_usage_suggestions,
+ options::OPT_fno_safe_buffer_usage_suggestions);
+
// Setup statistics file output.
SmallString<128> StatsFile = getStatsFileName(Args, Output, Input, D);
if (!StatsFile.empty()) {
Index: clang/lib/Analysis/UnsafeBufferUsage.cpp
===================================================================
--- clang/lib/Analysis/UnsafeBufferUsage.cpp
+++ clang/lib/Analysis/UnsafeBufferUsage.cpp
@@ -611,7 +611,8 @@
/// Scan the function and return a list of gadgets found with provided kits.
static std::tuple<FixableGadgetList, WarningGadgetList, DeclUseTracker>
-findGadgets(const Decl *D, const UnsafeBufferUsageHandler &Handler) {
+findGadgets(const Decl *D, const UnsafeBufferUsageHandler &Handler,
+ bool EmitSuggestions) {
struct GadgetFinderCallback : MatchFinder::MatchCallback {
FixableGadgetList FixableGadgets;
@@ -665,33 +666,37 @@
// clang-format off
M.addMatcher(
stmt(forEveryDescendant(
- eachOf(
- // A `FixableGadget` matcher and a `WarningGadget` matcher should not disable
- // each other (they could if they were put in the same `anyOf` group).
- // We also should make sure no two `FixableGadget` (resp. `WarningGadget`) matchers
- // match for the same node, so that we can group them
- // in one `anyOf` group (for better performance via short-circuiting).
stmt(anyOf(
-#define FIXABLE_GADGET(x) \
- x ## Gadget::matcher().bind(#x),
-#include "clang/Analysis/Analyses/UnsafeBufferUsageGadgets.def"
- // Also match DeclStmts because we'll need them when fixing
- // their underlying VarDecls that otherwise don't have
- // any backreferences to DeclStmts.
- declStmt().bind("any_ds")
- )),
- stmt(anyOf(
- // Add Gadget::matcher() for every gadget in the registry.
#define WARNING_GADGET(x) \
- allOf(x ## Gadget::matcher().bind(#x), notInSafeBufferOptOut(&Handler)),
+ allOf(x ## Gadget::matcher().bind(#x), notInSafeBufferOptOut(&Handler)),
#include "clang/Analysis/Analyses/UnsafeBufferUsageGadgets.def"
- // In parallel, match all DeclRefExprs so that to find out
- // whether there are any uncovered by gadgets.
- declRefExpr(anyOf(hasPointerType(), hasArrayType()), to(varDecl())).bind("any_dre")
- )))
- )),
- &CB
+ unless(stmt()) // Avoid a hanging comma.
+ ))
+ )), &CB
);
+
+ if (EmitSuggestions) {
+ M.addMatcher(
+ stmt(forEveryDescendant(
+ stmt(anyOf(
+ // It's ok for a FixableGadget to match a node that was previously
+ // matched by a WarningGadget.
+#define FIXABLE_GADGET(x) \
+ x ## Gadget::matcher().bind(#x),
+#include "clang/Analysis/Analyses/UnsafeBufferUsageGadgets.def"
+ // Add Gadget::matcher() for every gadget in the registry.
+ // In parallel, match all DeclRefExprs so that to find out
+ // whether there are any uncovered by gadgets.
+ declRefExpr(anyOf(hasPointerType(), hasArrayType()),
+ to(varDecl())).bind("any_dre"),
+ // Also match DeclStmts because we'll need them when fixing
+ // their underlying VarDecls that otherwise don't have
+ // any backreferences to DeclStmts.
+ declStmt().bind("any_ds")
+ ))
+ )), &CB
+ );
+ }
// clang-format on
M.match(*D->getBody(), D->getASTContext());
@@ -1131,17 +1136,30 @@
void clang::checkUnsafeBufferUsage(const Decl *D,
UnsafeBufferUsageHandler &Handler,
+ bool EmitSuggestions,
bool EmitFixits) {
assert(D && D->getBody());
+ assert(!(EmitFixits && !EmitSuggestions) &&
+ "Unsafe buffer usage fixits requested without suggestions!");
WarningGadgetSets UnsafeOps;
FixableGadgetSets FixablesForUnsafeVars;
DeclUseTracker Tracker;
{
- auto [FixableGadgets, WarningGadgets, TrackerRes] = findGadgets(D, Handler);
- UnsafeOps = groupWarningGadgetsByVar(std::move(WarningGadgets));
- FixablesForUnsafeVars = groupFixablesByVar(std::move(FixableGadgets));
+ auto [FixableGadgets, WarningGadgets, TrackerRes] =
+ findGadgets(D, Handler, EmitSuggestions);
+ if (EmitSuggestions) {
+ UnsafeOps = groupWarningGadgetsByVar(std::move(WarningGadgets));
+ FixablesForUnsafeVars = groupFixablesByVar(std::move(FixableGadgets));
+ } else {
+ // Don't group anything by variable if we aren't suggesting fixes.
+ UnsafeOps.noVar.reserve(WarningGadgets.size());
+ for (std::unique_ptr<WarningGadget> &G : WarningGadgets) {
+ UnsafeOps.noVar.push_back(std::move(G));
+ }
+ WarningGadgets.clear();
+ }
Tracker = std::move(TrackerRes);
}
Index: clang/include/clang/Driver/Options.td
===================================================================
--- clang/include/clang/Driver/Options.td
+++ clang/include/clang/Driver/Options.td
@@ -1560,6 +1560,11 @@
Group<f_Group>, Flags<[CC1Option]>,
HelpText<"Print a template comparison tree for differing templates">,
MarshallingInfoFlag<DiagnosticOpts<"ShowTemplateTree">>;
+defm safe_buffer_usage_suggestions : BoolFOption<"safe-buffer-usage-suggestions",
+ DiagnosticOpts<"ShowSafeBufferUsageSuggestions">, DefaultFalse,
+ PosFlag<SetTrue, [CC1Option],
+ "Display suggestions to update code associated with -Wunsafe-buffer-usage warnings">,
+ NegFlag<SetFalse>>;
def fdiscard_value_names : Flag<["-"], "fdiscard-value-names">, Group<f_clang_Group>,
HelpText<"Discard value names in LLVM IR">, Flags<[NoXarchOption]>;
def fno_discard_value_names : Flag<["-"], "fno-discard-value-names">, Group<f_clang_Group>,
Index: clang/include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -11789,6 +11789,8 @@
"used%select{| in pointer arithmetic| in buffer access}0 here">;
def note_unsafe_buffer_variable_fixit : Note<
"change type of '%0' to '%select{std::span|std::array|std::span::iterator}1' to preserve bounds information">;
+def note_safe_buffer_usage_suggestions_disabled : Note<
+ "pass -fsafe-buffer-usage-suggestions to receive code hardening suggestions">;
def err_loongarch_builtin_requires_la32 : Error<
"this builtin requires target: loongarch32">;
Index: clang/include/clang/Basic/DiagnosticOptions.def
===================================================================
--- clang/include/clang/Basic/DiagnosticOptions.def
+++ clang/include/clang/Basic/DiagnosticOptions.def
@@ -95,6 +95,8 @@
/// Column limit for formatting message diagnostics, or 0 if unused.
VALUE_DIAGOPT(MessageLength, 32, 0)
+DIAGOPT(ShowSafeBufferUsageSuggestions, 1, 0)
+
#undef DIAGOPT
#undef ENUM_DIAGOPT
#undef VALUE_DIAGOPT
Index: clang/include/clang/Analysis/Analyses/UnsafeBufferUsage.h
===================================================================
--- clang/include/clang/Analysis/Analyses/UnsafeBufferUsage.h
+++ clang/include/clang/Analysis/Analyses/UnsafeBufferUsage.h
@@ -54,7 +54,7 @@
// This function invokes the analysis and allows the caller to react to it
// through the handler class.
void checkUnsafeBufferUsage(const Decl *D, UnsafeBufferUsageHandler &Handler,
- bool EmitFixits);
+ bool EmitSuggestions, bool EmitFixits);
namespace internal {
// Tests if any two `FixItHint`s in `FixIts` conflict. Two `FixItHint`s
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
