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[PROTOTYPE] Add analyzer-only ABSL_ANALYZER_ASSUME primitive and consume it in the nullability checker #1159

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[PROTOTYPE] Add analyzer-only ABSL_ANALYZER_ASSUME primitive and consume it in the nullability checker #1159

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44 changes: 32 additions & 12 deletions gloop/util/status/ret_check.h
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Original file line number Diff line number Diff line change
Expand Up @@ -256,18 +256,38 @@ inline unsigned long long GetReferenceableValue(unsigned long long t) {
rhs) \
RET_CHECK((lhs)op(rhs))
#else
#define UTIL_TASK_CONTRIB_STATUS_MACROS_INTERNAL_RET_CHECK_OP(name, op, lhs, \
rhs) \
while ( \
std::string* _result = \
::util::internal_status_macros_ret_check::Check_##name##Impl( \
::util::internal_status_macros_ret_check::GetReferenceableValue( \
lhs), \
::util::internal_status_macros_ret_check::GetReferenceableValue( \
rhs), \
#lhs " " #op " " #rhs)) \
return ::util::internal_status_macros_ret_check::RetCheckFailSlowPath( \
::absl::SourceLocation::current(), _result)
// On the success path, additionally feed the comparison fact to Clang
// dataflow-based analyses via the shared `ABSL_ANALYZER_ASSUME` primitive (see
// "absl/base/optimization.h"), so they learn `lhs op rhs` (e.g.
// `p != nullptr`) from one shared vocabulary instead of per-analysis
// special-casing of the `Check_*Impl` helpers. `ABSL_ANALYZER_ASSUME` expands
// to nothing outside a static analyzer, so this single definition serves both
// production and analysis builds. `GetReferenceableValue` is kept on the real
// `Check_##name##Impl` call for ODR-safety of header-only integral constants;
// the assume reads the operands by value (`(lhs) op (rhs)`), so it never
// ODR-uses them. The failure path stays in the textually-last `else` so the
// returned `StatusBuilder` still chains `<< msg`, `.With(...)`, and
// `.SetNoLogging()`. The `switch (0) case 0: default:` blocker keeps the whole
// expansion a single, dangling-else-safe statement.
// NOLINTBEGIN(readability/braces)
#define UTIL_TASK_CONTRIB_STATUS_MACROS_INTERNAL_RET_CHECK_OP(name, op, lhs, \
rhs) \
switch (0) \
case 0: \
default: \
if (std::string* _result = \
::util::internal_status_macros_ret_check::Check_##name##Impl( \
::util::internal_status_macros_ret_check:: \
GetReferenceableValue(lhs), \
::util::internal_status_macros_ret_check:: \
GetReferenceableValue(rhs), \
#lhs " " #op " " #rhs); \
_result == nullptr) { \
ABSL_ANALYZER_ASSUME((lhs)op(rhs)); \
} else \
return ::util::internal_status_macros_ret_check::RetCheckFailSlowPath( \
::absl::SourceLocation::current(), _result)
// NOLINTEND(readability/braces)
#endif

#define RET_CHECK_EQ(lhs, rhs) \
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