Improve warning diagnostics

lib/lrama/warnings/implicit_empty.rb

@@ -20,7 +20,8 @@ def warn(grammar)
 
         grammar.rule_builders.each do |builder|
           if builder.rhs.empty?
-            @logger.warn("warning: empty rule without %empty")
+            lhs = builder.lhs #: Lrama::Lexer::Token::Base
+            @logger.warn(lhs.location.generate_error_message("empty rule for #{lhs.s_value} without %empty").chomp)
           end
         end
       end

lib/lrama/warnings/mixed_references.rb

@@ -24,7 +24,7 @@ def warn(grammar)
         build_grouped_usage(grammar).each do |rule, usage|
           next unless usage[:positional] && usage[:named]
 
-          @logger.warn("warning: rule `#{rule.as_comment}` mixes positional and named references; use named references consistently")
+          @logger.warn("rule `#{rule.as_comment}` mixes positional and named references; use named references consistently")
         end
       end
 

lib/lrama/warnings/name_conflicts.rb

@@ -55,7 +55,7 @@ def check_conflicts(parameterized_rules, symbol_names)
         parameterized_rules.each do |param_rule|
           next unless symbol_names.include?(param_rule.name)
 
-          @logger.warn("warning: parameterized rule name \"#{param_rule.name}\" conflicts with symbol name")
+          @logger.warn("parameterized rule name \"#{param_rule.name}\" conflicts with symbol name")
         end
       end
     end

spec/lrama/warnings/implicit_empty_spec.rb

@@ -19,16 +19,20 @@
     end
 
     context "when warnings true" do
-      it "has warns for parameterized rule redefined" do
+      it "warns with the rule location" do
         grammar = Lrama::Parser.new(y, "states/empty.y").parse
         grammar.prepare
         grammar.validate!
         states = Lrama::States.new(grammar, Lrama::Tracer.new(Lrama::Logger.new))
         states.compute
-        logger = Lrama::Logger.new
-        allow(logger).to receive(:warn)
+        out = StringIO.new
+        logger = Lrama::Logger.new(out)
         Lrama::Warnings.new(logger, true).warn(grammar, states)
-        expect(logger).to have_received(:warn).with("warning: empty rule without %empty")
+        expect(out.string).to eq(<<~WARNING)
+          warning: states/empty.y:9:0: empty rule for program without %empty
+             9 | program: /* empty */
+               | ^~~~~~~
+        WARNING
       end
     end
 
@@ -42,7 +46,7 @@
         logger = Lrama::Logger.new
         allow(logger).to receive(:warn)
         Lrama::Warnings.new(logger, false).warn(grammar, states)
-        expect(logger).not_to have_received(:warn).with("warning: empty rule without %empty")
+        expect(logger).not_to have_received(:warn)
       end
     end
   end

spec/lrama/warnings/mixed_references_spec.rb

@@ -32,7 +32,7 @@
 
         Lrama::Warnings.new(logger, true).warn(grammar, states)
 
-        expect(logger).to have_received(:warn).with("warning: rule `expr: NUM NUM` mixes positional and named references; use named references consistently")
+        expect(logger).to have_received(:warn).with("rule `expr: NUM NUM` mixes positional and named references; use named references consistently")
       end
 
       it "does not warn when named references are used consistently" do
@@ -100,7 +100,7 @@
 
         Lrama::Warnings.new(logger, true).warn(grammar, states)
 
-        expect(logger).to have_received(:warn).with(/warning: rule `expr: .*` mixes positional and named references; use named references consistently/).once
+        expect(logger).to have_received(:warn).with(/rule `expr: .*` mixes positional and named references; use named references consistently/).once
       end
 
       it "does not warn when positional references are used consistently" do
@@ -165,7 +165,7 @@
 
         Lrama::Warnings.new(logger, true).warn(grammar, states)
 
-        expect(logger).to have_received(:warn).with("warning: rule `expr: NUM` mixes positional and named references; use named references consistently")
+        expect(logger).to have_received(:warn).with("rule `expr: NUM` mixes positional and named references; use named references consistently")
       end
 
       it "warns when mixing address-of location references and named value references" do
@@ -198,7 +198,7 @@
 
         Lrama::Warnings.new(logger, true).warn(grammar, states)
 
-        expect(logger).to have_received(:warn).with("warning: rule `expr: NUM NUM` mixes positional and named references; use named references consistently")
+        expect(logger).to have_received(:warn).with("rule `expr: NUM NUM` mixes positional and named references; use named references consistently")
       end
 
       it "warns when mixing index and named value references" do
@@ -231,7 +231,7 @@
 
         Lrama::Warnings.new(logger, true).warn(grammar, states)
 
-        expect(logger).to have_received(:warn).with("warning: rule `expr: NUM` mixes positional and named references; use named references consistently")
+        expect(logger).to have_received(:warn).with("rule `expr: NUM` mixes positional and named references; use named references consistently")
       end
 
       it "does not warn when using only special and positional index references" do
@@ -296,7 +296,7 @@
 
         Lrama::Warnings.new(logger, true).warn(grammar, states)
 
-        expect(logger).to have_received(:warn).with("warning: rule `expr: NUM` mixes positional and named references; use named references consistently")
+        expect(logger).to have_received(:warn).with("rule `expr: NUM` mixes positional and named references; use named references consistently")
       end
 
       it "does not warn when mixing special LHS and positional references" do
@@ -458,7 +458,7 @@
 
         Lrama::Warnings.new(logger, true).warn(grammar, states)
 
-        expect(logger).to have_received(:warn).with("warning: rule `expr: LEFT tPLUS RIGHT` mixes positional and named references; use named references consistently")
+        expect(logger).to have_received(:warn).with("rule `expr: LEFT tPLUS RIGHT` mixes positional and named references; use named references consistently")
       end
 
       it "warns when mixing tagged LHS alias and positional references" do
@@ -490,7 +490,7 @@
 
         Lrama::Warnings.new(logger, true).warn(grammar, states)
 
-        expect(logger).to have_received(:warn).with("warning: rule `expr: NUM` mixes positional and named references; use named references consistently")
+        expect(logger).to have_received(:warn).with("rule `expr: NUM` mixes positional and named references; use named references consistently")
       end
     end
 

spec/lrama/warnings/name_conflicts_spec.rb

@@ -31,7 +31,7 @@
           logger = Lrama::Logger.new
           allow(logger).to receive(:warn)
           Lrama::Warnings.new(logger, true).warn(grammar, states)
-          expect(logger).to have_received(:warn).with('warning: parameterized rule name "option" conflicts with symbol name')
+          expect(logger).to have_received(:warn).with('parameterized rule name "option" conflicts with symbol name')
         end
       end
 
@@ -78,7 +78,7 @@
           logger = Lrama::Logger.new
           allow(logger).to receive(:warn)
           Lrama::Warnings.new(logger, true).warn(grammar, states)
-          expect(logger).to have_received(:warn).with('warning: parameterized rule name "program" conflicts with symbol name')
+          expect(logger).to have_received(:warn).with('parameterized rule name "program" conflicts with symbol name')
         end
       end
 
@@ -193,8 +193,8 @@
           logger = Lrama::Logger.new
           allow(logger).to receive(:warn)
           Lrama::Warnings.new(logger, true).warn(grammar, states)
-          expect(logger).to have_received(:warn).with('warning: parameterized rule name "option" conflicts with symbol name')
-          expect(logger).to have_received(:warn).with('warning: parameterized rule name "separated" conflicts with symbol name')
+          expect(logger).to have_received(:warn).with('parameterized rule name "option" conflicts with symbol name')
+          expect(logger).to have_received(:warn).with('parameterized rule name "separated" conflicts with symbol name')
         end
       end
     end