Fix miscellaneous lint warnings (#5093)

Summary:
Pull Request resolved: https://github.com/facebookresearch/faiss/pull/5093

Fix remaining miscellaneous lint warnings across 10 files:
- `facebook-hte-MultTypeDeclaration`: Split mixed-type declaration in AutoTune.cpp
- `facebook-hte-IdenticalOperands`: Rename variable in build.cpp to avoid false positive
- `facebook-hte-BadImplicitCast`: Add explicit cast in Index.cpp
- `performance-inefficient-vector-operation`: Add reserve() in IndexBinaryIVF.cpp
- `performance-for-range-copy`: Use const reference in IndexBinaryHash.cpp range-for
- `facebook-hte-UnassignedReleasedUniquePointer`: Capture release() results in IVFlib.cpp, IndexPreTransform.cpp
- `facebook-hte-UnqualifiedCall-sqrt`: Use std::sqrt() in MatrixStats.cpp
- `facebook-unused-include-check`: Remove unused includes in IndexIVF.cpp, IndexNNDescent.cpp, IndexNSG.cpp
- `clang-diagnostic-switch-enum`: Add missing enum cases in IndexAdditiveQuantizer.cpp, IndexIVFAdditiveQuantizer.cpp

Reviewed By: pankajsingh88

Differential Revision: D100592786

fbshipit-source-id: 1d324e30d79e967c345737bae6991e9a443622ee

faiss/AutoTune.cpp

@@ -279,7 +279,8 @@ size_t ParameterSpace::n_combinations() const {
 
 /// get string representation of the combination
 std::string ParameterSpace::combination_name(size_t cno) const {
-    char buf[1000], *wp = buf;
+    char buf[1000];
+    char* wp = buf;
     *wp = 0;
     for (size_t i = 0; i < parameter_ranges.size(); i++) {
         FAISS_THROW_IF_NOT_MSG(

faiss/IVFlib.cpp

@@ -492,7 +492,8 @@ IndexIVFResidualQuantizer* ivf_residual_from_quantizer(
                     faiss::METRIC_L2,
                     rq.search_type));
     index->own_fields = true;
-    rcq.release();
+    // Ownership transferred to index via own_fields = true
+    (void)rcq.release();
     index->by_residual = true;
     index->rq.initialize_from(rq, nlevel);
     index->is_trained = true;

faiss/Index.cpp

@@ -55,7 +55,7 @@ void Index::add_with_ids(
 
 size_t Index::remove_ids(const IDSelector& /*sel*/) {
     FAISS_THROW_MSG("remove_ids not implemented for this type of index");
-    return -1;
+    return static_cast<size_t>(-1);
 }
 
 void Index::reconstruct(idx_t, float*) const {

faiss/IndexBinaryIVF.cpp

@@ -526,6 +526,7 @@ void search_knn_hamming_count(
     idx_t max_codes = params ? params->max_codes : ivf->max_codes;
 
     std::vector<HCounterState<HammingComputer>> cs;
+    cs.reserve(nx);
     for (size_t i = 0; i < nx; ++i) {
         cs.push_back(
                 HCounterState<HammingComputer>(

faiss/IndexIVFAdditiveQuantizer.cpp

@@ -312,6 +312,7 @@ InvertedListScanner* IndexIVFAdditiveQuantizer::get_InvertedListScanner(
             case AdditiveQuantizer::ST_norm_rq2x4:
                 A(ST_norm_cqint8)
 #undef A
+            case AdditiveQuantizer::ST_count:
             default:
                 FAISS_THROW_FMT(
                         "search type %d not supported", aq->search_type);

faiss/IndexNSG.cpp

@@ -18,7 +18,6 @@
 #include <faiss/impl/AuxIndexStructures.h>
 #include <faiss/impl/FaissAssert.h>
 #include <faiss/impl/VisitedTable.h>
-#include <faiss/utils/distances.h>
 
 namespace faiss {
 

faiss/IndexPreTransform.cpp

@@ -129,7 +129,9 @@ const float* IndexPreTransform::apply_chain(idx_t n, const float* x) const {
         del2.swap(del);
         prev_x = xt;
     }
-    del.release();
+    // Intentionally release ownership: caller takes ownership of the returned
+    // buffer
+    (void)del.release();
     return prev_x;
 }
 

faiss/MatrixStats.cpp

@@ -52,7 +52,7 @@ void MatrixStats::PerDimStats::compute_mean_std() {
     if (var < 0) {
         var = 0;
     }
-    stddev = sqrt(var);
+    stddev = std::sqrt(var);
 }
 
 void MatrixStats::do_comment(const char* fmt, ...) {
@@ -163,8 +163,8 @@ MatrixStats::MatrixStats(size_t n_in, size_t d_in, const float* x)
     }
 
     { // norm stats
-        min_norm2 = sqrt(min_norm2);
-        max_norm2 = sqrt(max_norm2);
+        min_norm2 = std::sqrt(min_norm2);
+        max_norm2 = std::sqrt(max_norm2);
         do_comment(
                 "range of L2 norms=[%g, %g] (%zd null vectors)\n",
                 min_norm2,

faiss/build.cpp

@@ -10,14 +10,14 @@
 namespace faiss {
 
 bool has_omp() {
-    int omp = 1;
+    int omp_available = 1;
     // Detect whether OpenMP is enabled by using the 'max' reduction to render
     // the below assignment a no-op. This works:
     //  1) without starting any threads
     //  2) irrespective of the current thread limit
-#pragma omp parallel reduction(max : omp) num_threads(1)
-    omp = 0;
-    return omp != 0;
+#pragma omp parallel reduction(max : omp_available) num_threads(1)
+    omp_available = 0;
+    return omp_available != 0;
 }
 
 } // namespace faiss