lib.licenses: add compound licenses

ci/OWNERS

@@ -268,7 +268,7 @@ pkgs/development/python-modules/buildcatrust/ @ajs124 @lukegb @mweinelt
 /pkgs/applications/editors/jetbrains @leona-ya @theCapypara
 
 # Licenses
-/lib/licenses.nix @alyssais @emilazy @jopejoe1
+/lib/licenses @alyssais @emilazy @jopejoe1
 
 # Qt
 /pkgs/development/libraries/qt-5 @K900 @NickCao @SuperSandro2000 @ttuegel

lib/default.nix

@@ -73,7 +73,7 @@ let
       types = callLibs ./types.nix;
 
       # constants
-      licenses = callLibs ./licenses.nix;
+      licenses = callLibs ./licenses;
       sourceTypes = callLibs ./source-types.nix;
       systems = callLibs ./systems;
 

lib/licenses/default.nix

@@ -0,0 +1,7 @@
+{ lib }:
+let
+  licenses = import ./licenses.nix { inherit lib; };
+  operators = import ./operators.nix;
+  helpers = import ./helpers.nix { inherit lib; };
+in
+licenses // operators // helpers

lib/licenses/helpers.nix

@@ -0,0 +1,152 @@
+{ lib }:
+rec {
+  /**
+    Evaluate a license expression for a given predicate.
+
+    # Example
+
+    ```nix
+    evaluateProperty (x: x.free) true (with lib.licenses; AND [ ncsa (WITH asl20 llvm-exception) ])
+    ```
+    # Type
+
+    ```
+    evaluateProperty :: Function -> Bool -> AttrSet -> Bool
+    ```
+
+    # Arguments
+
+    - [predicate] checks for each license included in the license expression
+    - [permissive] whether to apply checks permissive or reciprocal
+    - [license] license expression to check
+  */
+  evaluateProperty =
+    predicate: permissive: license:
+    let
+      OR = if permissive then lib.any else lib.all;
+      AND = if permissive then lib.all else lib.any;
+    in
+    if license.licenseType == "simple" then
+      predicate license
+    else if license.licenseType == "compound" then
+      if license.operator == "OR" then
+        OR (x: evaluateProperty predicate permissive x) license.licenses
+      else if license.operator == "AND" then
+        AND (x: evaluateProperty predicate permissive x) license.licenses
+      else
+        throw "Unknown license operator"
+    else if license.licenseType == "exception" then
+      AND (x: evaluateProperty predicate permissive x) [
+        license.license
+        license.exception
+      ]
+    else if license.licenseType == "plus" then
+      evaluateProperty predicate permissive license.license
+    else
+      throw "Unknown license type or legacy license";
+
+  /**
+    Check whether a license expression is free.
+
+    # Example
+
+    ```nix
+    isFree (with lib.licenses; (AND [ ncsa (WITH asl20 llvm-exception) ]))
+    => true
+    ```
+
+    # Type
+
+    ```
+    isFree :: AttrSet -> Bool
+    ```
+
+    # Arguments
+
+    - [license] License expression to check if free
+  */
+  isFree = evaluateProperty (x: x.free) true;
+
+  /**
+    Check whether a license expression is redistributable.
+
+    # Example
+
+    ```nix
+    isRedistributable (with lib.licenses; (AND [ ncsa (WITH asl20 llvm-exception) ]))
+    => true
+    ```
+
+    # Type
+
+    ```
+    isRedistributable :: AttrSet -> Bool
+    ```
+
+    # Arguments
+
+    - [license] License expression to check if redistributable
+  */
+  isRedistributable = evaluateProperty (x: x.redistributable) true;
+
+  /**
+    Check whether any of the given licenses is required in the license expression.
+
+    # Example
+
+    ```nix
+    containsLicenses [ lib.licenses.asl20 ] (with lib.licenses; (AND [ ncsa (WITH asl20 llvm-exception) ]))
+    => true
+    ```
+
+    # Type
+
+    ```
+    containsLicenses :: List -> AttrSet -> Bool
+    ```
+
+    # Arguments
+
+    - [licenses] List of licenses to look
+    - [license] License expression to check
+  */
+  containsLicenses = licenses: evaluateProperty (x: lib.lists.elem x licenses) false;
+
+  /**
+    Convert a license expression to an SPDX license expression string.
+
+    # Example
+
+    ```nix
+    toSPDX (with lib.licenses; AND [ ncsa (WITH asl20 llvm-exception) ])
+    => "NCSA AND (Apache-2.0 WITH LLVM-exception)"
+    ```
+
+    # Type
+
+    ```
+    toSPDX :: AttrSet -> String
+    ```
+
+    # Arguments
+
+    - [license] License expression which to convert to spdx expression
+  */
+  toSPDX =
+    license:
+    let
+      mkBracket =
+        x:
+        if x.licenseType == "compound" || x.licenseType == "exception" then "(${toSPDX x})" else toSPDX x;
+    in
+    if license.licenseType == "simple" then
+      license.spdxId or "LicenseRef-nixos-${license.shortName}"
+    else if license.licenseType == "compound" then
+      lib.concatMapStringsSep " ${license.operator} " (x: mkBracket x) license.licenses
+    else if license.licenseType == "exception" then
+      "${mkBracket license.license} ${license.operator} ${mkBracket license.exception}"
+    else if license.licenseType == "plus" then
+      "${mkBracket license.license}${license.operator}"
+    else
+      throw "Unknown license type";
+}

lib/licenses/licenses.nix

@@ -21,6 +21,7 @@ let
         deprecated
         redistributable
         ;
+      licenseType = "simple";
     }
     // optionalAttrs (attrs ? spdxId) {
       inherit spdxId;

lib/licenses/operators.nix

@@ -0,0 +1,110 @@
+{
+  /**
+    This should be used when there is a choice of which license expression to use.
+    This is a disjunctive binary "OR" operator.
+
+    # Example
+
+    ```nix
+    OR [ lib.licenses.mit lib.licenses.asl20 ]
+    => { licenseType = "compound"; operator = "OR"; licenses = [ lib.licenses.mit lib.licenses.asl20 ] };
+    ```
+
+    # Type
+
+    ```
+    OR :: List -> AttrSet
+    ```
+
+    # Arguments
+
+    - [licenses] Possible licenses to choose from
+  */
+  OR = licenses: {
+    licenseType = "compound";
+    operator = "OR";
+    inherit licenses;
+  };
+
+  /**
+     Create a compound licenses where the user needs to follow both licenses,
+     eqivialent of spdx `and` modifier.
+
+    # Example
+
+    ```nix
+    AND [ lib.licenses.mit lib.licenses.asl20 ]
+    => { licenseType = "compound"; operator = "AND"; licenses = [ lib.licenses.mit lib.licenses.asl20 ] };
+    ```
+
+    # Type
+
+    ```
+    AND :: List -> AttrSet
+    ```
+
+    # Arguments
+
+    - [licenses] Licenses required to use
+  */
+  AND = licenses: {
+    licenseType = "compound";
+    operator = "AND";
+    inherit licenses;
+  };
+
+  /**
+     Create a licenses exception where a license has a license exception,
+     eqivialent of spdx `with` modifier.
+
+    # Example
+
+    ```nix
+    WITH lib.licenses.lgpl21Only lib.licenses.ocamlLgplLinkingException
+    => { licenseType = "exception"; operator = "WITH"; license = lib.licenses.lgpl21Only; exception = lib.licenses.ocamlLgplLinkingException; };
+    ```
+
+    # Type
+
+    ```
+    WITH :: AttrSet -> AttrSet -> AttrSet
+    ```
+
+    # Arguments
+
+    - [license] License to which the exception applies
+    - [exception] Exception to apply
+  */
+  WITH = license: exception: {
+    licenseType = "compound";
+    operator = "WITH";
+    inherit license exception;
+  };
+
+  /**
+     Create a licenses which can be upgraded to any later version of itself,
+     eqivialent of spdx `+` modifier
+
+    # Example
+
+    ```nix
+    PLUS lib.licenses.lgpl21Only
+    => { licenseType = "plus"; operator = "+"; license = lib.licenses.lgpl21Only; };
+    ```
+
+    # Type
+
+    ```
+    PLUS :: AttrSet -> AttrSet
+    ```
+
+    # Arguments
+
+    - [license] License to wich apply an exception
+  */
+  PLUS = license: {
+    licenseType = "plus";
+    operator = "+";
+    inherit license;
+  };
+}

pkgs/stdenv/generic/check-meta.nix

@@ -90,6 +90,8 @@ let
       && (
         if isList attrs.meta.license then
           any (l: elem l list) attrs.meta.license
+        else if attrs.meta.license ? "type" then
+          lib.licenses.containsLicenses list attrs.meta.license
         else
           elem attrs.meta.license list
       );
@@ -103,7 +105,9 @@ let
 
   isUnfree =
     licenses:
-    if isAttrs licenses then
+    if isAttrs licenses && licenses ? "type" then
+      !(lib.licenses.isFree licenses)
+    else if isAttrs licenses then
       !(licenses.free or true)
     # TODO: Returning false in the case of a string is a bug that should be fixed.
     # In a previous implementation of this function the function body