Patch Dafny to use the system Z3

In previous versions, it was sufficient to just pass /z3exe:/usr/bin/z3
in the dafny launcher script, but now, Dafny looks for its vendored
Z3 (which we don’t install) at runtime and prints a warning if it’s
gone.  Patch that behaviour away, hardcoding /usr/bin/z3 as the Z3
binary location.

3 files changed, 40 insertions, 1 deletions

diff --git a/debian/bin/dafny b/debian/bin/dafny
index 8950cf84..b4173036 100755
--- a/debian/bin/dafny
+++ b/debian/bin/dafny
@@ -1,2 +1,2 @@
 #!/bin/sh
-exec /usr/bin/cli /usr/lib/dafny/Dafny.exe /z3exe:/usr/bin/z3 "$@"
+exec /usr/bin/cli /usr/lib/dafny/Dafny.exe "$@"
diff --git a/debian/patches/series b/debian/patches/series
new file mode 100644
index 00000000..8dec5b79
--- /dev/null
+++ b/debian/patches/series
@@ -0,0 +1 @@
+use_system_z3.diff
diff --git a/debian/patches/use_system_z3.diff b/debian/patches/use_system_z3.diff
new file mode 100644
index 00000000..1e08c80c
--- /dev/null
+++ b/debian/patches/use_system_z3.diff
@@ -0,0 +1,38 @@
+Description: Use system Z3
+ Dafny by default looks for its vendored Z3.  Modify it to look for the system
+ Z3 installation instead.
+Forwarded: not-needed
+Author: Benjamin Barenblat <bbaren@mit.edu>
+--- a/Source/Dafny/DafnyOptions.cs
++++ b/Source/Dafny/DafnyOptions.cs
+@@ -283,29 +283,7 @@ namespace Microsoft.Dafny
+     /// so we vendor a Windows version.

+     /// </summary>

+     private void SetZ3ExecutableName() {

+-      var platform = (int)System.Environment.OSVersion.Platform;

+-

+-      // http://www.mono-project.com/docs/faq/technical/

+-      var isUnix = platform == 4 || platform == 128;

+-      

+-      var z3binName = isUnix ? "z3" : "z3.exe";

+-      var dafnyBinDir = System.IO.Path.GetDirectoryName(System.Reflection.Assembly.GetExecutingAssembly().Location);

+-      var z3BinDir = System.IO.Path.Combine(dafnyBinDir, "z3", "bin");

+-      var z3BinPath = System.IO.Path.Combine(z3BinDir, z3binName);

+-

+-      if (!System.IO.File.Exists(z3BinPath) && !isUnix) {

+-        // This is most likely a Windows user running from source without downloading z3 

+-        // separately; this is ok, since we vendor z3.exe.

+-        z3BinPath = System.IO.Path.Combine(dafnyBinDir, z3binName);

+-      }

+-      

+-      if (!System.IO.File.Exists(z3BinPath) && errorReporter != null) {

+-        var tok = new Bpl.Token(1, 1) { filename = "*** " };

+-        errorReporter.Warning(MessageSource.Other, tok, "Could not find '{0}' in '{1}'.{2}Downloading and extracting a Z3 distribution to Dafny's 'Binaries' folder would solve this issue; for now, we'll rely on Boogie to find Z3.", 

+-          z3binName, z3BinDir, System.Environment.NewLine);

+-      } else {

+-        Z3ExecutablePath = z3BinPath;

+-      }

++      Z3ExecutablePath = "/usr/bin/z3";

+     }

+ 

+     public override void Usage() {