juliac: Add rudimentary Windows support

This was essentially working as-is, except for our reliance on a C
compiler.

Author: topolarity

contrib/Artifacts.toml

@@ -0,0 +1,19 @@
+[[mingw-w64]]
+arch = "x86_64"
+git-tree-sha1 = "b17bda08a19173572926f43a48aad5ef3d845e7c"
+os = "windows"
+lazy = true
+
+    [[mingw-w64.download]]
+    sha256 = "53645e06775a55733580426341395c67dda20a664af83bcda76a1d052b618b59"
+    url = "https://github.com/JuliaLang/PackageCompiler.jl/releases/download/v2.1.24/x86_64-14.2.0-release-posix-seh-msvcrt-rt_v12-rev0.tar.gz"
+
+[[mingw-w64]]
+arch = "i686"
+git-tree-sha1 = "76b9f278e7de1d7dfdfe3a786afbe9c1e29003ea"
+os = "windows"
+lazy = true
+
+    [[mingw-w64.download]]
+    sha256 = "d049bd771e01b02f2ca9274435f0e6f9f4f295bf2af72a8059dd851c52144910"
+    url = "https://github.com/JuliaLang/PackageCompiler.jl/releases/download/v2.1.24/i686-14.2.0-release-posix-dwarf-msvcrt-rt_v12-rev0.tar.gz"

contrib/juliac.jl

@@ -1,6 +1,8 @@
 # Julia compiler wrapper script
 # NOTE: The interface and location of this script are considered unstable/experimental
 
+using LazyArtifacts
+
 module JuliaConfig
     include(joinpath(@__DIR__, "julia-config.jl"))
 end
@@ -28,6 +30,57 @@ if help !== nothing
     exit(0)
 end
 
+# Copied from PackageCompiler
+# https://github.com/JuliaLang/PackageCompiler.jl/blob/1c35331d8ef81494f054bbc71214811253101993/src/PackageCompiler.jl#L147-L190
+function get_compiler_cmd(; cplusplus::Bool=false)
+    cc = get(ENV, "JULIA_CC", nothing)
+    path = nothing
+    @static if Sys.iswindows()
+        path = joinpath(LazyArtifacts.artifact"mingw-w64",
+                        "extracted_files",
+                        (Int==Int64 ? "mingw64" : "mingw32"),
+                        "bin",
+                        cplusplus ? "g++.exe" : "gcc.exe")
+        compiler_cmd = `$path`
+    end
+    if cc !== nothing
+        compiler_cmd = Cmd(Base.shell_split(cc))
+        path = nothing
+    elseif !Sys.iswindows()
+        compilers_cpp = ("g++", "clang++")
+        compilers_c = ("gcc", "clang")
+        found_compiler = false
+        if cplusplus
+            for compiler in compilers_cpp
+                if Sys.which(compiler) !== nothing
+                    compiler_cmd = `$compiler`
+                    found_compiler = true
+                    break
+                end
+            end
+        end
+        if !found_compiler
+            for compiler in compilers_c
+                if Sys.which(compiler) !== nothing
+                    compiler_cmd = `$compiler`
+                    found_compiler = true
+                    if cplusplus && !WARNED_CPP_COMPILER[]
+                        @warn "could not find a c++ compiler (g++ or clang++), falling back to $compiler, this might cause link errors"
+                        WARNED_CPP_COMPILER[] = true
+                    end
+                    break
+                end
+            end
+        end
+        found_compiler || error("could not find a compiler, looked for ",
+            join(((cplusplus ? compilers_cpp : ())..., compilers_c...), ", ", " and "))
+    end
+    if path !== nothing
+        compiler_cmd = addenv(compiler_cmd, "PATH" => string(ENV["PATH"], ";", dirname(path)))
+    end
+    return compiler_cmd
+end
+
 # arguments to forward to julia compilation process
 julia_args = []
 
@@ -77,6 +130,7 @@ function get_rpath(; relative::Bool = false)
     end
 end
 
+cc = get_compiler_cmd()
 absfile = abspath(file)
 cflags = JuliaConfig.cflags(; framework=false)
 cflags = Base.shell_split(cflags)
@@ -90,7 +144,6 @@ init_path = joinpath(tmpdir, "init.a")
 img_path = joinpath(tmpdir, "img.a")
 bc_path = joinpath(tmpdir, "img-bc.a")
 
-
 function precompile_env()
     # Pre-compile the environment
     # (otherwise obscure error messages will occur)
@@ -123,7 +176,7 @@ function compile_products()
                   }
                   """)
     end
-    run(`cc $(cflags) -g -c -o $init_path $initsrc_path`)
+    run(`$(cc) $(cflags) -g -c -o $init_path $initsrc_path`)
 end
 
 function link_products()
@@ -139,11 +192,11 @@ function link_products()
     julia_libs = Base.shell_split(Base.isdebugbuild() ? "-ljulia-debug -ljulia-internal-debug" : "-ljulia -ljulia-internal")
     try
         if output_type == "--output-lib"
-            cmd2 = `cc $(allflags) $(rpath) -o $outname -shared -Wl,$(Base.Linking.WHOLE_ARCHIVE) $img_path  -Wl,$(Base.Linking.NO_WHOLE_ARCHIVE) $init_path  $(julia_libs)`
+            cmd2 = `$(cc) $(allflags) $(rpath) -o $outname -shared -Wl,$(Base.Linking.WHOLE_ARCHIVE) $img_path  -Wl,$(Base.Linking.NO_WHOLE_ARCHIVE) $init_path  $(julia_libs)`
         elseif output_type == "--output-sysimage"
-            cmd2 = `cc $(allflags) $(rpath) -o $outname -shared -Wl,$(Base.Linking.WHOLE_ARCHIVE) $img_path  -Wl,$(Base.Linking.NO_WHOLE_ARCHIVE)             $(julia_libs)`
+            cmd2 = `$(cc) $(allflags) $(rpath) -o $outname -shared -Wl,$(Base.Linking.WHOLE_ARCHIVE) $img_path  -Wl,$(Base.Linking.NO_WHOLE_ARCHIVE)             $(julia_libs)`
         else
-            cmd2 = `cc $(allflags) $(rpath) -o $outname -Wl,$(Base.Linking.WHOLE_ARCHIVE) $img_path -Wl,$(Base.Linking.NO_WHOLE_ARCHIVE) $init_path $(julia_libs)`
+            cmd2 = `$(cc) $(allflags) $(rpath) -o $outname -Wl,$(Base.Linking.WHOLE_ARCHIVE) $img_path -Wl,$(Base.Linking.NO_WHOLE_ARCHIVE) $init_path $(julia_libs)`
         end
         verbose && println("Running: $cmd2")
         run(cmd2)