uses: restore formula-level exception handler

This is a temporary measure until:

- #1862 is merged
- I can a test on `brew uses` against every formula in the official
  taps to verify that exceptions are no longer raised.

1 files changed, 42 insertions, 37 deletions

diff --git a/Library/Homebrew/cmd/uses.rb b/Library/Homebrew/cmd/uses.rb
index f9af36754..20fc146bf 100644
--- a/Library/Homebrew/cmd/uses.rb
+++ b/Library/Homebrew/cmd/uses.rb
@@ -47,49 +47,54 @@ module Homebrew
 
     uses = formulae.select do |f|
       used_formulae.all? do |ff|
-        if recursive
-          deps = f.recursive_dependencies do |dependent, dep|
-            if dep.recommended?
-              Dependency.prune if ignores.include?("recommended?") || dependent.build.without?(dep)
-            elsif dep.optional?
-              Dependency.prune if !includes.include?("optional?") && !dependent.build.with?(dep)
-            elsif dep.build?
-              Dependency.prune unless includes.include?("build?")
-            end
+        begin
+          if recursive
+            deps = f.recursive_dependencies do |dependent, dep|
+              if dep.recommended?
+                Dependency.prune if ignores.include?("recommended?") || dependent.build.without?(dep)
+              elsif dep.optional?
+                Dependency.prune if !includes.include?("optional?") && !dependent.build.with?(dep)
+              elsif dep.build?
+                Dependency.prune unless includes.include?("build?")
+              end
 
-            # If a tap isn't installed, we can't find the dependencies of one
-            # its formulae, and an exception will be thrown if we try.
-            if dep.is_a?(TapDependency) && !dep.tap.installed?
-              Dependency.keep_but_prune_recursive_deps
+              # If a tap isn't installed, we can't find the dependencies of one
+              # its formulae, and an exception will be thrown if we try.
+              if dep.is_a?(TapDependency) && !dep.tap.installed?
+                Dependency.keep_but_prune_recursive_deps
+              end
             end
-          end
-          reqs = f.recursive_requirements do |dependent, req|
-            if req.recommended?
-              Requirement.prune if ignores.include?("recommended?") || dependent.build.without?(req)
-            elsif req.optional?
-              Requirement.prune if !includes.include?("optional?") && !dependent.build.with?(req)
-            elsif req.build?
-              Requirement.prune unless includes.include?("build?")
+            reqs = f.recursive_requirements do |dependent, req|
+              if req.recommended?
+                Requirement.prune if ignores.include?("recommended?") || dependent.build.without?(req)
+              elsif req.optional?
+                Requirement.prune if !includes.include?("optional?") && !dependent.build.with?(req)
+              elsif req.build?
+                Requirement.prune unless includes.include?("build?")
+              end
+            end
+          else
+            deps = f.deps.reject do |dep|
+              ignores.any? { |ignore| dep.send(ignore) } && !includes.any? { |include| dep.send(include) }
+            end
+            reqs = f.requirements.reject do |req|
+              ignores.any? { |ignore| req.send(ignore) } && !includes.any? { |include| req.send(include) }
             end
           end
-        else
-          deps = f.deps.reject do |dep|
-            ignores.any? { |ignore| dep.send(ignore) } && !includes.any? { |include| dep.send(include) }
-          end
-          reqs = f.requirements.reject do |req|
-            ignores.any? { |ignore| req.send(ignore) } && !includes.any? { |include| req.send(include) }
-          end
-        end
-        next true if deps.any? do |dep|
-          begin
-            dep.to_formula.full_name == ff.full_name
-          rescue
-            dep.name == ff.name
+          next true if deps.any? do |dep|
+            begin
+              dep.to_formula.full_name == ff.full_name
+            rescue
+              dep.name == ff.name
+            end
           end
-        end
 
-        reqs.any? do |req|
-          req.name == ff.name || [ff.name, ff.full_name].include?(req.default_formula)
+          reqs.any? do |req|
+            req.name == ff.name || [ff.name, ff.full_name].include?(req.default_formula)
+          end
+        rescue FormulaUnavailableError
+          # Silently ignore this case as we don't care about things used in
+          # taps that aren't currently tapped.
         end
       end
     end