[GitHub] [arrow] jonkeane commented on a diff in pull request #11666: ARROW-14638: [C++][R] Unknown C compiler / ccache on Arch Linux

[GitBox <gi...@apache.org>]

jonkeane commented on code in PR #11666:
URL: https://github.com/apache/arrow/pull/11666#discussion_r854575316


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r/tools/nixlibs.R:
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@@ -301,8 +301,10 @@ build_libarrow <- function(src_dir, dst_dir) {
     # EXTRA_CMAKE_FLAGS will often be "", but it's convenient later to have it defined
     EXTRA_CMAKE_FLAGS = Sys.getenv("EXTRA_CMAKE_FLAGS"),
     # Make sure we build with the same compiler settings that R is using
-    CC = R_CMD_config("CC"),
-    CXX = paste(R_CMD_config("CXX11"), R_CMD_config("CXX11STD")),
+    # but we remove ccache, since `ARROW_USE_CCACHE` does that for our dependencies, and
+    # having ccache here as well leads to compile errors
+    CC = gsub("^.*ccache", "", R_CMD_config("CC")),
+    CXX = paste(gsub("^.*ccache", "", R_CMD_config("CXX11")), R_CMD_config("CXX11STD")),

Review Comment:
   I'm not 100% sure this is what we should do, but it _does_ work. 
   
   Our dependencies + builds should use ccache by default if it's available:
   
   https://github.com/apache/arrow/blob/83cc5727571c6291dad513e5a2cab15e6182b569/cpp/CMakeLists.txt#L195-L207
   
   So we shouldn't need to _also_ specify ccache before g++, etc. and that seems to be what has been causing issues for some folks.



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