Build fix: PrometheusExporter::Collect was made const. (#428)

jupp0r/prometheus-cpp#323

Also format with newer version of cmake-format.

Author: g-easy

opencensus/common/internal/CMakeLists.txt

@@ -26,8 +26,8 @@ opencensus_lib(
 opencensus_lib(common_stats_object DEPS absl::time)
 
 # Define NOMINMAX to fix build errors when compiling with MSVC.
-target_compile_definitions(opencensus_common_stats_object INTERFACE
-                           $<$<CXX_COMPILER_ID:MSVC>:NOMINMAX>)
+target_compile_definitions(opencensus_common_stats_object
+                           INTERFACE $<$<CXX_COMPILER_ID:MSVC>:NOMINMAX>)
 
 opencensus_lib(common_string_vector_hash DEPS absl::hash)
 

opencensus/exporters/stats/prometheus/internal/prometheus_exporter.cc

@@ -25,7 +25,7 @@ namespace opencensus {
 namespace exporters {
 namespace stats {
 
-std::vector<prometheus::MetricFamily> PrometheusExporter::Collect() {
+std::vector<prometheus::MetricFamily> PrometheusExporter::Collect() const {
   const auto data = opencensus::stats::StatsExporter::GetViewData();
   std::vector<prometheus::MetricFamily> output(data.size());
   for (int i = 0; i < data.size(); ++i) {

opencensus/exporters/stats/prometheus/prometheus_exporter.h

@@ -41,7 +41,7 @@ namespace stats {
 // PrometheusExporter is thread-safe.
 class PrometheusExporter final : public ::prometheus::Collectable {
  public:
-  std::vector<prometheus::MetricFamily> Collect() override;
+  std::vector<prometheus::MetricFamily> Collect() const override;
 };
 
 }  // namespace stats

opencensus/stats/CMakeLists.txt

@@ -57,8 +57,8 @@ opencensus_lib(
   absl::span)
 
 # Define NOMINMAX to fix build errors when compiling with MSVC.
-target_compile_definitions(opencensus_stats_core PUBLIC
-                           $<$<CXX_COMPILER_ID:MSVC>:NOMINMAX>)
+target_compile_definitions(opencensus_stats_core
+                           PUBLIC $<$<CXX_COMPILER_ID:MSVC>:NOMINMAX>)
 
 opencensus_lib(
   stats_recording

opencensus/trace/CMakeLists.txt

@@ -50,8 +50,8 @@ opencensus_lib(
   absl::span)
 
 # Define NOMINMAX to fix build errors when compiling with MSVC.
-target_compile_definitions(opencensus_trace PUBLIC
-                           $<$<CXX_COMPILER_ID:MSVC>:NOMINMAX>)
+target_compile_definitions(opencensus_trace
+                           PUBLIC $<$<CXX_COMPILER_ID:MSVC>:NOMINMAX>)
 
 opencensus_lib(
   trace_b3