[R-SIG-Mac] Installing svglite in R-devel

[Duncan Murdoch]

I'm trying to install the svglite package in R-devel on my M3 Mac 
running Sonoma 14.7.1, and getting these results:

>> install.packages("svglite")
> --- Please select a CRAN mirror for use in this session ---
> trying URL 'https://cloud.r-project.org/src/contrib/svglite_2.2.1.tar.gz'
> Content type 'application/x-gzip' length 134155 bytes (131 KB)
> ==================================================
> downloaded 131 KB
> 
> * installing *source* package ‘svglite’ ...
> ** this is package ‘svglite’ version ‘2.2.1’
> ** package ‘svglite’ successfully unpacked and MD5 sums checked
> ** using staged installation
> ** libs
> using C++ compiler: ‘Apple clang version 16.0.0 (clang-1600.0.26.6)’
> using SDK: ‘MacOSX15.2.sdk’
> clang++ -std=gnu++17 -I"/Users/murdoch/R/R-devel/include" -DNDEBUG  -I'/Users/murdoch/R/R-devel/library/cpp11/include' -I'/Users/murdoch/R/R-devel/library/systemfonts/include' -I'/Users/murdoch/R/R-devel/library/textshaping/include' -isystem /opt/R/arm64/include    -fPIC  -g -O2   -c SvgStream.cpp -o SvgStream.o
> clang++ -std=gnu++17 -I"/Users/murdoch/R/R-devel/include" -DNDEBUG  -I'/Users/murdoch/R/R-devel/library/cpp11/include' -I'/Users/murdoch/R/R-devel/library/systemfonts/include' -I'/Users/murdoch/R/R-devel/library/textshaping/include' -isystem /opt/R/arm64/include    -fPIC  -g -O2   -c cpp11.cpp -o cpp11.o
> clang++ -std=gnu++17 -I"/Users/murdoch/R/R-devel/include" -DNDEBUG  -I'/Users/murdoch/R/R-devel/library/cpp11/include' -I'/Users/murdoch/R/R-devel/library/systemfonts/include' -I'/Users/murdoch/R/R-devel/library/textshaping/include' -isystem /opt/R/arm64/include    -fPIC  -g -O2   -c devSVG.cpp -o devSVG.o
> clang++ -std=gnu++17 -dynamiclib -Wl,-headerpad_max_install_names -undefined dynamic_lookup -L/Users/murdoch/R/R-devel/lib -L/usr/local/lib -o svglite.so SvgStream.o cpp11.o devSVG.o -lpng -lz -L/Users/murdoch/R/R-devel/lib -lR
> ld: library 'png' not found
> clang++: error: linker command failed with exit code 1 (use -v to see invocation)
> make: *** [svglite.so] Error 1
> ERROR: compilation failed for package ‘svglite’
> * removing ‘/Users/murdoch/R/R-devel/library/svglite’

I do have libpng installed:

> murdoch using djmair4 /opt/R/arm64/lib
> $ ls -l libpng*
> lrwxr-xr-x  1 root  admin       10 30 Mar 18:58 libpng.a@ -> libpng16.a
> lrwxr-xr-x  1 root  admin       11 30 Mar 18:58 libpng.la@ -> libpng16.la
> -rw-r--r--  1 root  admin  1094008 30 Mar 18:58 libpng16.a
> -rwxr-xr-x  1 root  admin      895 30 Mar 18:58 libpng16.la*

I have a config.site file in the R-devel-src folder, modified with these 
changes:

> Index: config.site
> ===================================================================
> --- config.site	(revision 88220)
> +++ config.site	(working copy)
> @@ -45,7 +45,7 @@
>  ## It is also necessary to set the architecture here, e.g. 'gcc -m32'.
>  ## If this is a wrapper it should pass on --version to the real compiler.
>  ## This will be replaced by CC23 (see below) if a C23 compiler is found.
> -## CC=
> +CC=clang
>  
>  ## Debugging and optimization options for the C compiler.
>  ## Use this to specify CFLAGS for the version of the C compiler
> @@ -111,12 +111,12 @@
>  ## options (such as defines) for the C preprocessor and compiler.
>  ## If unset defaults to '-I/usr/local/include', with '-I/sw/include'
>  ## prepended on systems using Fink with root '/sw'.
> -## CPPFLAGS=
> +CPPFLAGS='-isystem /opt/R/arm64/include'
>  
>  ## The command which runs the Fortran compiler.
>  ## Used for both fixed-form and free-form Fortran
>  ## If this is a wrapper it should pass on --version to the real compiler.
> -## FC=
> +FC="/opt/gfortran/bin/gfortran -mtune=native"
>  
>  ## Options for the Fortran compiler.
>  ## Use this to specify comilation flags for fixed-form Fortran.
> @@ -223,7 +223,7 @@
>  ## and then looks under the names 'c++', 'g++', 'CC' and more OS-specific
>  ## names (from autoconf).
>  ## If this is a wrapper it should pass on --version to the real compiler.
> -## CXX=
> +CXX=clang++
>  
>  ## Options for the C++ compiler.
>  ## CXXFLAGS=
> @@ -255,7 +255,7 @@
>  
>  ## Objective-C(++), mainly for macOS
>  ## On macOS, Apple clang with additional gcc flag -fobjc-exceptions
> -## OBJC=
> +OBJC=$CC
>  ## OBJCFLAGS=
>  ## OBJC_LIBS-
>  ## Objective-C compiler, usually the same as $CXX $CXXSTD

Can anyone spot what needs fixing?

Duncan Murdoch