Compiler: added --error-trace to show a complete error trace.

Hide traces like "Nil trace" and other traces by default, which makes understanding errors much harder, but still allow to show them with a flag.
crystal-lang · Sep 15, 2016 · 611849c · 611849c · asterite · Sep 15, 2016
1 parent f021f1f
commit 611849c
Showing 7 changed files with 30 additions and 9 deletions.
diff --git a/src/compiler/crystal/command.cr b/src/compiler/crystal/command.cr
@@ -304,6 +304,10 @@ class Crystal::Command
         output_format = f
       end
 
+      opts.on("--error-trace", "Show full error trace") do
+        compiler.show_error_trace = true
+      end
+
       opts.on("-h", "--help", "Show this message") do
         puts opts
         exit

diff --git a/src/compiler/crystal/command/spec.cr b/src/compiler/crystal/command/spec.cr
@@ -19,6 +19,9 @@ class Crystal::Command
       opts.on("-D FLAG", "--define FLAG", "Define a compile-time flag") do |flag|
         compiler.flags << flag
       end
+      opts.on("--error-trace", "Show full error trace") do
+        compiler.show_error_trace = true
+      end
       opts.on("--release", "Compile in release mode") do
         compiler.release = true
       end

diff --git a/src/compiler/crystal/compiler.cr b/src/compiler/crystal/compiler.cr
@@ -106,6 +106,9 @@ module Crystal
     # Default standard error to use in a compilation.
     property stderr : IO = STDERR
 
+    # Whether to show error trace
+    property? show_error_trace = false
+
     # Compiles the given *source*, with *output_filename* as the name
     # of the generated executable.
     #
@@ -150,6 +153,7 @@ module Crystal
       program.wants_doc = wants_doc?
       program.color = color?
       program.stdout = stdout
+      program.show_error_trace = show_error_trace?
       program
     end
 

diff --git a/src/compiler/crystal/program.cr b/src/compiler/crystal/program.cr
@@ -103,6 +103,9 @@ module Crystal
     # Default standard output to use in a program, while compiling.
     property stdout : IO = STDOUT
 
+    # Whether to show error trace
+    property? show_error_trace = false
+
     def initialize
       super(self, self, "main")
 

diff --git a/src/compiler/crystal/semantic/bindings.cr b/src/compiler/crystal/semantic/bindings.cr
@@ -35,7 +35,7 @@ module Crystal
       # See if we can find where the mismatched type came from
       if from && !ex.inner && (freeze_type = @freeze_type) && type.is_a?(UnionType) && type.includes_type?(freeze_type) && type.union_types.size == 2
         other_type = type.union_types.find { |type| type != freeze_type }
-        trace = from.find_owner_trace(other_type)
+        trace = from.find_owner_trace(freeze_type.program, other_type)
         ex.inner = trace
       end
 
@@ -50,7 +50,7 @@ module Crystal
       if !freeze_type.includes_type?(invalid_type.program.nil) && invalid_type.includes_type?(invalid_type.program.nil)
         # This means that an instance variable become nil
         if self.is_a?(MetaTypeVar) && (nil_reason = self.nil_reason)
-          inner = MethodTraceException.new(nil, [] of ASTNode, nil_reason)
+          inner = MethodTraceException.new(nil, [] of ASTNode, nil_reason, freeze_type.program.show_error_trace?)
         end
       end
 
@@ -192,7 +192,7 @@ module Crystal
       type
     end
 
-    def find_owner_trace(owner)
+    def find_owner_trace(program, owner)
       owner_trace = [] of ASTNode
       node = self
 
@@ -210,7 +210,7 @@ module Crystal
         end
       end
 
-      MethodTraceException.new(owner, owner_trace, nil_reason)
+      MethodTraceException.new(owner, owner_trace, nil_reason, program.show_error_trace?)
     end
   end
 

diff --git a/src/compiler/crystal/semantic/call_error.cr b/src/compiler/crystal/semantic/call_error.cr
@@ -79,7 +79,7 @@ class Crystal::Call
     if defs.empty?
       check_macro_wrong_number_of_arguments(def_name)
 
-      owner_trace = obj.try &.find_owner_trace(owner)
+      owner_trace = obj.try &.find_owner_trace(owner.program, owner)
       similar_name = owner.lookup_similar_def_name(def_name, self.args.size, block)
 
       error_msg = String.build do |msg|
@@ -213,7 +213,7 @@ class Crystal::Call
     end
 
     if args.size == 1 && args.first.type.includes_type?(program.nil)
-      owner_trace = args.first.find_owner_trace(program.nil)
+      owner_trace = args.first.find_owner_trace(program, program.nil)
     end
 
     arg_names = [] of Array(String)

diff --git a/src/compiler/crystal/semantic/exception.cr b/src/compiler/crystal/semantic/exception.cr
@@ -157,7 +157,7 @@ module Crystal
   end
 
   class MethodTraceException < Exception
-    def initialize(@owner : Type?, @trace : Array(ASTNode), @nil_reason : NilReason?)
+    def initialize(@owner : Type?, @trace : Array(ASTNode), @nil_reason : NilReason?, @show : Bool)
       super(nil)
     end
 
@@ -174,15 +174,22 @@ module Crystal
 
     def append_to_s(source, io)
       has_trace = @trace.any?(&.location)
+      nil_reason = @nil_reason
+
+      if !@show && (has_trace || nil_reason)
+        io.print "Rerun with --error-trace to show a complete error trace."
+        return
+      end
+
       if has_trace
         io.puts ("=" * 80)
-        io << "\n#{@owner} trace:"
+        io.puts
+        io << "#{@owner} trace:"
         @trace.each do |node|
           print_with_location node, io
         end
       end
 
-      nil_reason = @nil_reason
       return unless nil_reason
 
       if has_trace