Use double brace as should be in C++11

test/gtest_factor_gnss_tdcp.cpp

@@ -152,30 +152,30 @@ void setUpProblem()
     cap_k->addStateBlock("T", std::make_shared<StateBlock>(clock_drift_k, false), prb);
 
     // features r
-    obsd_t obs1_r{0};
+    obsd_t obs1_r{{0}};
     obs1_r.L[0] = prange1_r.prange;
     ftr1_r = FeatureBase::emplace<FeatureGnssSatellite>(cap_r, obs1_r, sat1_r, prange1_r);
-    obsd_t obs2_r{0};
+    obsd_t obs2_r{{0}};
     obs2_r.L[0] = prange2_r.prange;
     ftr2_r = FeatureBase::emplace<FeatureGnssSatellite>(cap_r, obs2_r, sat2_r, prange2_r);
-    obsd_t obs3_r{0};
+    obsd_t obs3_r{{0}};
     obs3_r.L[0] = prange3_r.prange;
     ftr3_r = FeatureBase::emplace<FeatureGnssSatellite>(cap_r, obs3_r, sat3_r, prange3_r);
-    obsd_t obs4_r{0};
+    obsd_t obs4_r{{0}};
     obs4_r.L[0] = prange4_r.prange;
     ftr4_r = FeatureBase::emplace<FeatureGnssSatellite>(cap_r, obs4_r, sat4_r, prange4_r);
 
     // features k
-    obsd_t obs1_k{0};
+    obsd_t obs1_k{{0}};
     obs1_k.L[0] = prange1_k.prange;
     ftr1_k = FeatureBase::emplace<FeatureGnssSatellite>(cap_k, obs1_k, sat1_k, prange1_k);
-    obsd_t obs2_k{0};
+    obsd_t obs2_k{{0}};
     obs2_k.L[0] = prange2_k.prange;
     ftr2_k = FeatureBase::emplace<FeatureGnssSatellite>(cap_k, obs2_k, sat2_k, prange2_k);
-    obsd_t obs3_k{0};
+    obsd_t obs3_k{{0}};
     obs3_k.L[0] = prange3_k.prange;
     ftr3_k = FeatureBase::emplace<FeatureGnssSatellite>(cap_k, obs3_k, sat3_k, prange3_k);
-    obsd_t obs4_k{0};
+    obsd_t obs4_k{{0}};
     obs4_k.L[0] = prange4_k.prange;
     ftr4_k = FeatureBase::emplace<FeatureGnssSatellite>(cap_k, obs4_k, sat4_k, prange4_k);