Support #fmt precision for bools, with same rules as strings

Not totally confident this is desirable. The alternative would be to make it a
compile error.

2 files changed, 14 insertions, 2 deletions

diff --git a/src/lib/ExtFmt.rs b/src/lib/ExtFmt.rs
index bbcb14bd..4be03858 100644
--- a/src/lib/ExtFmt.rs
+++ b/src/lib/ExtFmt.rs
@@ -358,11 +358,15 @@ mod RT {
     }
 
     fn conv_bool(&conv cv, bool b) -> str {
+        auto s;
         if (b) {
-            ret pad(cv, "true");
+            s = "true";
         } else {
-            ret pad(cv, "false");
+            s = "false";
         }
+        // Run the boolean conversion through the string conversion logic,
+        // giving it the same rules for precision, etc.
+        ret conv_str(cv, s);
     }
 
     fn conv_char(&conv cv, char c) -> str {
diff --git a/src/test/run-pass/syntax-extension-fmt.rs b/src/test/run-pass/syntax-extension-fmt.rs
index 935c87c1..5c66b17a 100644
--- a/src/test/run-pass/syntax-extension-fmt.rs
+++ b/src/test/run-pass/syntax-extension-fmt.rs
@@ -104,4 +104,12 @@ fn main() {
   test(#fmt("%.5x", 127u), "0007f");
   test(#fmt("%.5t", 3u), "00011");
   test(#fmt("%.5c", 'A'), "A");
+
+  // Bool precision. I'm not sure if it's good or bad to have bool
+  // conversions support precision - it's not standard printf so we
+  // can do whatever. For now I'm making it behave the same as string
+  // conversions.
+  test(#fmt("%.b", true), "");
+  test(#fmt("%.0b", true), "");
+  test(#fmt("%.1b", true), "t");
 }