CompilerSelector: raise when no compatible compiler

This replaces the old behaviour of falling back to the original
compiler with no messaging.

Fixes Homebrew/homebrew#19170.
Fixes mistydemeo/tigerbrew#45.

1 files changed, 8 insertions, 1 deletions

diff --git a/Library/Homebrew/compilers.rb b/Library/Homebrew/compilers.rb
index b871e1aeb..37ce6cdb2 100644
--- a/Library/Homebrew/compilers.rb
+++ b/Library/Homebrew/compilers.rb
@@ -53,11 +53,18 @@ class CompilerSelector
     end
   end
 
+  # Attempts to select an appropriate alternate compiler, but
+  # if none can be found raises CompilerError instead
   def compiler
     begin
       cc = @compilers.pop
     end while @f.fails_with?(cc)
-    cc.nil? ? @old_compiler : cc.name
+
+    if cc.nil?
+      raise CompilerSelectionError
+    else
+      cc.name
+    end
   end
 
   private