CRAN does want these lines. See RcppCore/RcppParallel#194 (comment)

aadler · aadler · commit e3a4ca2a3e87 · 2023-01-31T15:41:56.000-05:00
diff --git a/src/Makevars b/src/Makevars
@@ -1 +1,2 @@
+CXX_STD = CXX17
 PKG_LIBS += $(shell ${R_HOME}/bin/Rscript -e "RcppParallel::RcppParallelLibs()")
diff --git a/src/Makevars.win b/src/Makevars.win
@@ -1,3 +1,4 @@
+CXX_STD = CXX17
 PKG_CXXFLAGS += -DRCPP_PARALLEL_USE_TBB=1
 
 PKG_LIBS += $(shell "${R_HOME}/bin${R_ARCH_BIN}/Rscript.exe" \

Original file line number	Diff line number	Diff line change
`@@ -1 +1,2 @@`
	`1`	`+CXX_STD = CXX17`
`1`	`2`	`PKG_LIBS += $(shell ${R_HOME}/bin/Rscript -e "RcppParallel::RcppParallelLibs()")`
Original file line number	Diff line number	Diff line change
`@@ -1,3 +1,4 @@`
	`1`	`+CXX_STD = CXX17`
`1`	`2`	`PKG_CXXFLAGS += -DRCPP_PARALLEL_USE_TBB=1`
`2`	`3`
`3`	`4`	`PKG_LIBS += $(shell "${R_HOME}/bin${R_ARCH_BIN}/Rscript.exe" \`