From 6a1377178a143b288275c6d61ff21259bba40ee5 Mon Sep 17 00:00:00 2001
From: Justin Ethier <justin.ethier@gmail.com>
Date: Mon, 28 Sep 2020 13:32:13 -0400
Subject: [PATCH] Issue #412 - Fix expand within a cond-expand

Allow these dependencies to be recognized by Cyclone.
---
 CHANGELOG.md                           |  3 +++
 cyclone.scm                            |  4 ++--
 examples/game-of-life/example/grid.sld |  3 +++
 examples/game-of-life/example/life.sld | 18 +++++++-----------
 scheme/cyclone/libraries.sld           | 11 +++++++----
 5 files changed, 22 insertions(+), 17 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index abf9c5b7..3655d32d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,9 @@
 Bug Fixes
 
 - The compiler now displays a helpful error message to the user when compilation of a program fails due to an error building a dependent library.
+- Enhanced `cond-expand` support in a library declaration to
+  - Properly handle cases where there is more than one `cond-expand` sub-expression. EG: two `begin` expressions, a `begin` / `import`, etc.
+  - Properly handle the case where `export` is defined by `cond-expand`. Previously such exports would not be recognized by code importing the library.
 
 ## 0.21 - September 17, 2020
 
diff --git a/cyclone.scm b/cyclone.scm
index a2030c48..45248a58 100644
--- a/cyclone.scm
+++ b/cyclone.scm
@@ -182,7 +182,7 @@
       (report:elapsed "imports:")
       (trace:info "imports:")
       (trace:info imports)
-      (set! imported-vars (lib:imports->idb imports append-dirs prepend-dirs))
+      (set! imported-vars (lib:imports->idb imports append-dirs prepend-dirs (base-expander)))
       (report:elapsed "resolved imports:")
       (trace:info "resolved imports:")
       (trace:info imported-vars)
@@ -245,7 +245,7 @@
             (set! imports (append imports (car program:imports/code)))
             (trace:info "imports:")
             (trace:info imports)
-            (set! imported-vars (lib:imports->idb imports append-dirs prepend-dirs))
+            (set! imported-vars (lib:imports->idb imports append-dirs prepend-dirs (base-expander)))
             (report:elapsed "resolved imports:")
             (trace:info "resolved imports:")
             (trace:info imported-vars)
diff --git a/examples/game-of-life/example/grid.sld b/examples/game-of-life/example/grid.sld
index cfefb242..52a9431a 100644
--- a/examples/game-of-life/example/grid.sld
+++ b/examples/game-of-life/example/grid.sld
@@ -1,7 +1,10 @@
 ; Example from draft 6 of R7RS
 (define-library (example grid)
+  (cond-expand
+   (cyclone
     (export make rows cols ref each
             put!) ;(rename put! set!))
+   ))
     (import (scheme base))
     (begin
       ;; Create an NxM grid.
diff --git a/examples/game-of-life/example/life.sld b/examples/game-of-life/example/life.sld
index 86780dd0..0b87f0cc 100644
--- a/examples/game-of-life/example/life.sld
+++ b/examples/game-of-life/example/life.sld
@@ -1,21 +1,17 @@
 (define-library (example life)
-  (import (except (scheme base) set!)
-         ; (scheme write)
-         ; (example grid)
-          )
+  (import (except (scheme base) set!))
   (cond-expand
     (cyclone
      (import (scheme write))
-;     ))
-;  (cond-expand
-;    (cyclone
      (import (example grid))
-           ))
+     
+     ))
            
-  ;(cond-expand
-  ;  (cyclone
+  (cond-expand
+    (cyclone
   (export life)
-  ;))
+  ))
+
   (cond-expand
     (cyclone
     (begin
diff --git a/scheme/cyclone/libraries.sld b/scheme/cyclone/libraries.sld
index 8d690bf7..ef73f487 100644
--- a/scheme/cyclone/libraries.sld
+++ b/scheme/cyclone/libraries.sld
@@ -440,12 +440,15 @@
     " "))
 
 ;; Read export list for a given import
-(define (lib:import->export-list import append-dirs prepend-dirs)
+(define (lib:import->export-list import append-dirs prepend-dirs expander)
   (let* ((lib-name (lib:import->library-name import))
          (dir (string-append (lib:import->filename lib-name ".sld" append-dirs prepend-dirs)))
          (fp (open-input-file dir))
          (lib (read-all fp))
-         (exports (lib:exports (car lib))))
+         (lib* (if expander
+                   (list (lib:cond-expand (car lib) expander))
+                   lib))
+         (exports (lib:exports (car lib*))))
     (close-input-port fp)
     (lib:import-set/exports->imports import exports)))
 
@@ -551,7 +554,7 @@
 ;;
 ;; TODO: convert this to use a hashtable. Initially a-lists
 ;; will be used to prove out the concept, but this is inefficient
-(define (lib:imports->idb imports append-dirs prepend-dirs)
+(define (lib:imports->idb imports append-dirs prepend-dirs expander)
  (apply
    append
    (map 
@@ -563,7 +566,7 @@
               (cons id lib-name)
               ids))
           '()
-           (lib:import->export-list import-set append-dirs prepend-dirs))))
+           (lib:import->export-list import-set append-dirs prepend-dirs expander))))
      (map lib:list->import-set imports))))
 
 ;; Convert from the import DB to a list of identifiers that are imported.