diff --git a/nongnu/packages/mono.scm b/nongnu/packages/mono.scm
index 023cb95..5dc2201 100644
--- a/nongnu/packages/mono.scm
+++ b/nongnu/packages/mono.scm
@@ -328,3 +328,281 @@ command line interface.")
(description "")
;; TODO: License?
(license license:expat))))
+
+;; TODO: Make fetcher.
+(define* (nuget-fetch #:key name version url sha256)
+ (if name
+ (origin
+ (method url-fetch)
+ (uri url)
+ (file-name (string-append name "-" version))
+ (sha256
+ (base32 sha256)))
+ (origin
+ (method url-fetch)
+ (uri url)
+ (sha256
+ (base32 sha256)))))
+
+(define-public msbuild
+ (let ((date "2019.07.26.14.57")
+ ;; (bootstrap-version "0.08")
+ )
+ (package
+ (name "msbuild")
+ (version "16.3")
+ (source
+ (origin
+ (method url-fetch)
+ (uri (string-append
+ "https://download.mono-project.com/sources/msbuild/msbuild-"
+ version "+xamarinxplat." date ".tar.xz")) ;
+ ;; (file-name (git-file-name name version))
+ (sha256
+ (base32
+ "1zcdfx4xsh62wj3g1jc2an0lppsfs691lz4dv05xbgi01aq1hk6a"))))
+ (build-system gnu-build-system)
+ (inputs
+ `(("mono" ,mono-6)))
+ (native-inputs
+ `(("dotnet-sdk" ,dotnet-sdk)
+ ("nuget" ,nuget)
+ ("unzip" ,unzip)
+ ("xplat" ,(origin
+ (method url-fetch)
+ ;; (uri "https://github.com/mono/msbuild/releases/download/0.07/mono_msbuild_xplat-master-8f608e49.zip")
+ (uri (string-append "https://github.com/mono/msbuild/releases/download/0.07/mono_msbuild_xplat-master-8f608e49.zip"))
+ ;; (file-name "mono_msbuild_6.4.0.208.zip")
+ (sha256
+ (base32
+ "1jxq3fk9a6q2a8i9zacxaz3fkvc22i9qvzlpa7wbb95h42g0ffhq"))))
+ ;; ("microsoft.build"
+ ;; ,(nuget-fetch #:version "14.3.0"
+ ;; #:url "https://www.nuget.org/api/v2/package/microsoft.build/14.3.0"
+ ;; #:sha256 "1zamn3p8xxi0wsjlpln0y71ncb977f3fp08mvaz4wmbmi76nr0rz"))
+ ("microsoft.dotnet.arcade.sdk"
+ ,(nuget-fetch #:version "1.0.0-beta.19372.10"
+ #:url (string-append "https://dotnetfeed.blob.core.windows.net/dotnet-core/"
+ "flatcontainer/microsoft.dotnet.arcade.sdk/1.0.0-beta.19372.10/"
+ "microsoft.dotnet.arcade.sdk.1.0.0-beta.19372.10.nupkg")
+ #:sha256 "1lii0yg4fbsma80mmvw2zwplc26abb46q6gkxwbsbkyszkw128hv"))
+ ("sn"
+ ,(nuget-fetch #:version "1.0.0"
+ #:url (string-append "https://dotnetfeed.blob.core.windows.net/dotnet-core/"
+ "flatcontainer/sn/1.0.0/sn.1.0.0.nupkg")
+ #:sha256 "1012fcdc6vq2355v86h434s6p2nnqgpdapb7p25l4h39g5q8p1qs"))
+ ("microbuild.core"
+ ,(nuget-fetch #:name "microbuild.core"
+ #:version "0.2.0"
+ #:url "https://www.nuget.org/api/v2/package/microbuild.core/0.2.0"
+ #:sha256 "0q4s45jskbyxfx4ay6znnvv94zma2wd85b8rwmwszd2nb0xl3194"))
+ ("microbuild.core.sentinel"
+ ,(nuget-fetch #:version "1.0.0"
+ #:url (string-append
+ "https://dotnetfeed.blob.core.windows.net/"
+ "dotnet-core/flatcontainer/microbuild.core.sentinel/"
+ "1.0.0/microbuild.core.sentinel.1.0.0.nupkg")
+ #:sha256 "035kqx5fkapql108n222lz8psvxk04mv3dy1qg3h08i4b8j3dy8i"))
+ ("vswhere"
+ ,(nuget-fetch #:name "vswhere"
+ #:version "2.6.7"
+ #:url "https://www.nuget.org/api/v2/package/vswhere/2.6.7"
+ #:sha256 "0h4k5i96p7633zzf4xsv7615f9x72rr5qr7b9934ri2y6gshfcwk"))
+ ("microsoft.diasymreader.pdb2pdb"
+ ,(nuget-fetch #:version "1.1.0-beta1-62506-02"
+ #:url (string-append
+ "https://dotnetfeed.blob.core.windows.net/dotnet-core/"
+ "flatcontainer/microsoft.diasymreader.pdb2pdb/"
+ "1.1.0-beta1-62506-02/"
+ "microsoft.diasymreader.pdb2pdb.1.1.0-beta1-62506-02.nupkg")
+ #:sha256 "1dkhpmq5aw34nndvb4xc370866vf33x70zrjhgvnpwwspb6vb0zh"))
+ ("microsoft.dotnet.signtool"
+ ,(nuget-fetch #:version "1.0.0-beta.19372.10"
+ #:url (string-append
+ "https://dotnetfeed.blob.core.windows.net/dotnet-core/"
+ "flatcontainer/microsoft.dotnet.signtool/"
+ "1.0.0-beta.19372.10/"
+ "microsoft.dotnet.signtool.1.0.0-beta.19372.10.nupkg")
+ #:sha256 "1f2im2lilw10zslfclxh49knr542jy7q09p009flxsgn68riy0j6"))))
+ (arguments
+ `(#:phases
+ (modify-phases %standard-phases
+ (delete 'configure)
+ (replace 'build
+ (lambda* (#:key inputs #:allow-other-keys)
+ (let* ((unzip (string-append (assoc-ref inputs "unzip") "/bin/unzip"))
+ (xplat (assoc-ref inputs "xplat"))
+ (nuget (string-append (assoc-ref inputs "nuget") "/bin/nuget"))
+ (dotnet-sdk (assoc-ref inputs "dotnet-sdk"))
+ (libhostfxr (string-append dotnet-sdk "/host/fxr/3.1.1/libhostfxr.so"))
+ (microsoft.dotnet.arcade.sdk (assoc-ref inputs "microsoft.dotnet.arcade.sdk")))
+ ;; Set up nuget packages.
+ (setenv "HOME" (string-append (getcwd) "/fake-home"))
+ (for-each
+ (lambda (mono-dep)
+ (invoke nuget "add" (assoc-ref inputs mono-dep) "-Source" "guix"))
+ '("microsoft.dotnet.arcade.sdk"
+ "sn"
+ "microbuild.core"
+ "microbuild.core.sentinel"
+ "vswhere"
+ "microsoft.diasymreader.pdb2pdb"
+ "microsoft.dotnet.signtool"))
+ (invoke nuget "sources" "Disable" "-Name" "nuget.org")
+ (invoke nuget "sources" "Add" "-Name" "guix" "-Source" (string-append (getcwd) "/guix"))
+ ;; Extract bootstrap.
+ (mkdir-p "artifacts")
+ (invoke unzip xplat "-d" "artifacts")
+ (rename-file ;; (string-append "artifacts/msbuild-" ,bootstrap-version)
+ "artifacts/msbuild" "artifacts/mono-msbuild")
+ (chmod "artifacts/mono-msbuild/MSBuild.dll" #o755)
+ (symlink libhostfxr
+ (string-append
+ "artifacts/mono-msbuild/SdkResolvers/Microsoft.DotNet.MSBuildSdkResolver/"
+ (basename libhostfxr)))
+ ;; Prevent installer from running.
+ (with-output-to-file "eng/common/dotnet-install.sh"
+ (lambda _
+ (format #t "#!~a~%" (which "bash"))))
+ ;; msbuild response files to use only our source
+ (with-output-to-file "artifacts/mono-msbuild/MSBuild.rsp"
+ (lambda _
+ (display "/p:RestoreSources=guix\n")))
+ (with-output-to-file "src/MSBuild/MSBuild.rsp"
+ (lambda _
+ (display "/p:RestoreSources=guix\n")))
+
+ (substitute* "./eng/cibuild_bootstrapped_msbuild.sh"
+ (("\t/bin/bash") (string-append "\t" (which "bash"))))
+ (pk 'BUILDING)
+ (invoke "./eng/cibuild_bootstrapped_msbuild.sh"
+ "--host_type" "mono"
+ "--configuration" "Release"
+ ;; TODO there are some (many?) failing tests
+ "--skip_tests" "/p:DisableNerdbankVersioning=true")))))))
+ (supported-systems '("x86_64-linux"))
+ (home-page "https://github.com/mono/msbuild")
+ (synopsis "Implementation of the Microsoft build system for Mono")
+ (description "This is the Mono version of Microsoft Build Engine, the
+build platform for .NET, and Visual Studio.")
+ (license license:expat))))
+
+;; (define-public msbuild
+;; (let ((date "2020.01.10.05.36"))
+;; (package
+;; (name "msbuild")
+;; (version "16.5")
+;; (source
+;; (origin
+;; (method git-fetch)
+;; (uri (git-reference
+;; (url "https://github.com/mono/linux-packaging-msbuild")
+;; (commit (string-append "upstream/" version "+xamarinxplat." date))))
+;; (file-name (git-file-name name version))
+;; (sha256
+;; (base32
+;; "1knircr25qxvmm5v3mar3xfvcycrbn4l03kyhfx8jmyzjxf5slcg"))))
+;; (build-system gnu-build-system)
+;; (inputs
+;; `(("mono" ,mono)))
+;; (native-inputs
+;; `(("dotnet-sdk" ,dotnet-sdk)
+;; ("unzip" ,unzip)))
+;; (arguments
+;; `(#:phases
+;; (modify-phases %standard-phases
+;; (delete 'configure)
+;; (replace 'build
+;; (lambda _
+;; ;; TODO there are some (many?) failing tests
+;; (invoke "./eng/cibuild_bootstrapped_msbuild.sh"
+;; "--host_type" "mono"
+;; "--configuration" "Release"
+;; "--skip_tests" "/p:DisableNerdbankVersioning=true"))))))
+;; (supported-systems '("x86_64-linux"))
+;; (home-page "https://github.com/mono/msbuild;")
+;; (synopsis "Implementation of the Microsoft build system for Mono")
+;; (description "This is the Mono version of Microsoft Build Engine, the
+;; build platform for .NET, and Visual Studio.")
+;; (license license:expat))))
+
+;; (define-public msbuild
+;; (let ((date "2020.01.10.05.36")
+;; (bootstrap-version "0.08"))
+;; (package
+;; (name "msbuild")
+;; (version "16.5")
+;; (source
+;; (origin
+;; (method url-fetch)
+;; (uri (string-append
+;; "https://download.mono-project.com/sources/msbuild/msbuild-"
+;; version "+xamarinxplat." date ".tar.xz")) ;
+;; ;; (file-name (git-file-name name version))
+;; (sha256
+;; (base32
+;; "19ki9ch4wxkh0l9jnsjr5fc7zx6lmpkmdklk3wxwsgmdakn3jws8"
+;; ;; "1knircr25qxvmm5v3mar3xfvcycrbn4l03kyhfx8jmyzjxf5slcg"
+;; ))))
+;; (build-system gnu-build-system)
+;; (inputs
+;; `(("mono" ,mono)))
+;; (native-inputs
+;; `(("dotnet-sdk" ,dotnet-sdk)
+;; ("unzip" ,unzip)
+;; ("xplat" ,(origin
+;; (method url-fetch)
+;; ;; (uri "https://github.com/mono/msbuild/releases/download/0.07/mono_msbuild_xplat-master-8f608e49.zip")
+;; (uri (string-append "https://github.com/mono/msbuild/releases/download/"
+;; bootstrap-version "/mono_msbuild_6.4.0.208.zip"))
+;; ;; (file-name "mono_msbuild_6.4.0.208.zip")
+;; (sha256
+;; (base32
+;; "0w9x1sj8nrsfghf7qm7dbcbc4yxhnzyhsrpl5slblfiyrwddm3xk"
+;; ;; "1jxq3fk9a6q2a8i9zacxaz3fkvc22i9qvzlpa7wbb95h42g0ffhq"
+;; ))))))
+;; (arguments
+;; `(#:phases
+;; (modify-phases %standard-phases
+;; (delete 'configure)
+;; (replace 'build
+;; (lambda* (#:key inputs #:allow-other-keys)
+;; (let* ((unzip (string-append (assoc-ref inputs "unzip") "/bin/unzip"))
+;; (xplat (assoc-ref inputs "xplat"))
+;; (dotnet-sdk (assoc-ref inputs "dotnet-sdk"))
+;; (libhostfxr (string-append dotnet-sdk "/host/fxr/3.1.1/libhostfxr.so")))
+;; (mkdir-p "artifacts")
+;; (invoke unzip xplat "-d" "artifacts")
+;; (rename-file ;; (string-append "artifacts/msbuild-" ,bootstrap-version)
+;; "artifacts/msbuild" "artifacts/mono-msbuild")
+;; (chmod "artifacts/mono-msbuild/MSBuild.dll" #o755)
+;; (symlink libhostfxr
+;; (string-append
+;; "artifacts/mono-msbuild/SdkResolvers/Microsoft.DotNet.MSBuildSdkResolver/"
+;; (basename libhostfxr)))
+;; ;; Prevent installer from running.
+;; (with-output-to-file "eng/common/dotnet-install.sh"
+;; (lambda _
+;; (format #t "#!~a/bin/bash~%" (which "bash"))))
+;; ;; msbuild response files to use only our source
+;; (with-output-to-file "artifacts/mono-msbuild/MSBuild.rsp"
+;; (lambda _
+;; (display "/p:RestoreSources=guix\n")))
+;; (with-output-to-file "src/MSBuild/MSBuild.rsp"
+;; (lambda _
+;; (display "/p:RestoreSources=guix\n")))
+
+;; (substitute* "./eng/cibuild_bootstrapped_msbuild.sh"
+;; (("\t/bin/bash") (string-append "\t" (which "bash"))))
+;; (pk 'BUILDING)
+;; (invoke "./eng/cibuild_bootstrapped_msbuild.sh"
+;; "--host_type" "mono"
+;; "--configuration" "Release"
+;; ;; TODO there are some (many?) failing tests
+;; "--skip_tests" "/p:DisableNerdbankVersioning=true")))))))
+;; (supported-systems '("x86_64-linux"))
+;; (home-page "https://github.com/mono/msbuild;")
+;; (synopsis "Implementation of the Microsoft build system for Mono")
+;; (description "This is the Mono version of Microsoft Build Engine, the
+;; build platform for .NET, and Visual Studio.")
+;; (license license:expat))))