Fix warnings for referenced non-hoisted functions.

Fixes #1034

Also added `expect_warnings` functionality to test framework.

3 files changed, 167 insertions, 2 deletions

diff --git a/lib/compress.js b/lib/compress.js
index d42f84d1..e47be97b 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -801,7 +801,9 @@ merge(Compressor.prototype, {
     };
 
     function extract_declarations_from_unreachable_code(compressor, stat, target) {
-        compressor.warn("Dropping unreachable code [{file}:{line},{col}]", stat.start);
+        if (!(stat instanceof AST_Defun)) {
+            compressor.warn("Dropping unreachable code [{file}:{line},{col}]", stat.start);
+        }
         stat.walk(new TreeWalker(function(node){
             if (node instanceof AST_Definitions) {
                 compressor.warn("Declarations in unreachable code! [{file}:{line},{col}]", node.start);
diff --git a/test/compress/issue-1034.js b/test/compress/issue-1034.js
new file mode 100644
index 00000000..039af2ed
--- /dev/null
+++ b/test/compress/issue-1034.js
@@ -0,0 +1,137 @@
+non_hoisted_function_after_return: {
+    options = {
+        hoist_funs: false, dead_code: true, conditionals: true, comparisons: true,
+        evaluate: true, booleans: true, loops: true, unused: true, keep_fargs: true,
+        if_return: true, join_vars: true, cascade: true, side_effects: true
+    }
+    input: {
+        function foo(x) {
+            if (x) {
+                return bar();
+                not_called1();
+            } else {
+                return baz();
+                not_called2();
+            }
+            function bar() { return 7; }
+            return not_reached;
+            function UnusedFunction() {}
+            function baz() { return 8; }
+        }
+    }
+    expect: {
+        function foo(x) {
+            return x ? bar() : baz();
+            function bar() { return 7 }
+            function baz() { return 8 }
+        }
+    }
+    expect_warnings: [
+        'WARN: Dropping unreachable code [test/compress/issue-1034.js:11,16]',
+        "WARN: Dropping unreachable code [test/compress/issue-1034.js:14,16]",
+        "WARN: Dropping unreachable code [test/compress/issue-1034.js:17,12]",
+        "WARN: Dropping unused function UnusedFunction [test/compress/issue-1034.js:18,21]"
+    ]
+}
+
+non_hoisted_function_after_return_2a: {
+    options = {
+        hoist_funs: false, dead_code: true, conditionals: true, comparisons: true,
+        evaluate: true, booleans: true, loops: true, unused: true, keep_fargs: true,
+        if_return: true, join_vars: true, cascade: true, side_effects: true,
+        collapse_vars: false
+    }
+    input: {
+        function foo(x) {
+            if (x) {
+                return bar(1);
+                var a = not_called(1);
+            } else {
+                return bar(2);
+                var b = not_called(2);
+            }
+            var c = bar(3);
+            function bar(x) { return 7 - x; }
+            function nope() {}
+            return b || c;
+        }
+    }
+    expect: {
+        // NOTE: Output is correct, but suboptimal. Not a regression. Can be improved in future.
+        //       This output is run through non_hoisted_function_after_return_2b with same flags.
+        function foo(x) {
+            if (x) {
+                return bar(1);
+            } else {
+                return bar(2);
+                var b;
+            }
+            var c = bar(3);
+            function bar(x) {
+                return 7 - x;
+            }
+            return b || c;
+        }
+    }
+    expect_warnings: [
+        "WARN: Dropping unreachable code [test/compress/issue-1034.js:48,16]",
+        "WARN: Declarations in unreachable code! [test/compress/issue-1034.js:48,16]",
+        "WARN: Dropping unreachable code [test/compress/issue-1034.js:51,16]",
+        "WARN: Declarations in unreachable code! [test/compress/issue-1034.js:51,16]",
+        "WARN: Dropping unused variable a [test/compress/issue-1034.js:48,20]",
+        "WARN: Dropping unused function nope [test/compress/issue-1034.js:55,21]"
+    ]
+}
+
+non_hoisted_function_after_return_2b: {
+    options = {
+        hoist_funs: false, dead_code: true, conditionals: true, comparisons: true,
+        evaluate: true, booleans: true, loops: true, unused: true, keep_fargs: true,
+        if_return: true, join_vars: true, cascade: true, side_effects: true,
+        collapse_vars: false
+    }
+    input: {
+        // Note: output of test non_hoisted_function_after_return_2a run through compress again
+        function foo(x) {
+            if (x) {
+                return bar(1);
+            } else {
+                return bar(2);
+                var b;
+            }
+            var c = bar(3);
+            function bar(x) {
+                return 7 - x;
+            }
+            return b || c;
+        }
+    }
+    expect: {
+        // the output we would have liked to see from non_hoisted_function_after_return_2a
+        function foo(x) {
+            return bar(x ? 1 : 2);
+            function bar(x) { return 7 - x; }
+        }
+    }
+    expect_warnings: [
+        // Notice that some warnings are repeated by multiple compress passes.
+        // Not a regression. There is room for improvement here.
+        // Warnings should be cached and only output if unique.
+        "WARN: Dropping unreachable code [test/compress/issue-1034.js:100,16]",
+        "WARN: Declarations in unreachable code! [test/compress/issue-1034.js:100,16]",
+        "WARN: Dropping unreachable code [test/compress/issue-1034.js:100,16]",
+        "WARN: Declarations in unreachable code! [test/compress/issue-1034.js:100,16]",
+        "WARN: Dropping unreachable code [test/compress/issue-1034.js:100,16]",
+        "WARN: Declarations in unreachable code! [test/compress/issue-1034.js:100,16]",
+        "WARN: Dropping unreachable code [test/compress/issue-1034.js:100,16]",
+        "WARN: Declarations in unreachable code! [test/compress/issue-1034.js:100,16]",
+        "WARN: Dropping unreachable code [test/compress/issue-1034.js:102,12]",
+        "WARN: Declarations in unreachable code! [test/compress/issue-1034.js:102,12]",
+        "WARN: Dropping unreachable code [test/compress/issue-1034.js:106,12]",
+        "WARN: Dropping unreachable code [test/compress/issue-1034.js:100,16]",
+        "WARN: Declarations in unreachable code! [test/compress/issue-1034.js:100,16]",
+        "WARN: Dropping unused variable b [test/compress/issue-1034.js:100,20]",
+        "WARN: Dropping unused variable c [test/compress/issue-1034.js:102,16]"
+    ]
+}
+
diff --git a/test/run-tests.js b/test/run-tests.js
index fcb1b375..b4333b7a 100755
--- a/test/run-tests.js
+++ b/test/run-tests.js
@@ -88,6 +88,14 @@ function run_compress_tests() {
             var options = U.defaults(test.options, {
                 warnings: false
             });
+            var warnings_emitted = [];
+            var original_warn_function = U.AST_Node.warn_function;
+            if (test.expect_warnings) {
+                U.AST_Node.warn_function = function(text) {
+                    warnings_emitted.push("WARN: " + text);
+                };
+                options.warnings = true;
+            }
             var cmp = new U.Compressor(options, true);
             var output_options = test.beautify || {};
             var expect;
@@ -117,6 +125,24 @@ function run_compress_tests() {
                 failures++;
                 failed_files[file] = 1;
             }
+            else if (test.expect_warnings) {
+                U.AST_Node.warn_function = original_warn_function;
+                var expected_warnings = make_code(test.expect_warnings, {
+                    beautify: false,
+                    quote_style: 2, // force double quote to match JSON
+                });
+                var actual_warnings = JSON.stringify(warnings_emitted);
+                actual_warnings = actual_warnings.split(process.cwd() + "/").join("");
+                if (expected_warnings != actual_warnings) {
+                    log("!!! failed\n---INPUT---\n{input}\n---EXPECTED WARNINGS---\n{expected_warnings}\n---ACTUAL WARNINGS---\n{actual_warnings}\n\n", {
+                        input: input_code,
+                        expected_warnings: expected_warnings,
+                        actual_warnings: actual_warnings,
+                    });
+                    failures++;
+                    failed_files[file] = 1;
+                }
+            }
         }
         var tests = parse_test(path.resolve(dir, file));
         for (var i in tests) if (tests.hasOwnProperty(i)) {
@@ -168,7 +194,7 @@ function parse_test(file) {
             }
             if (node instanceof U.AST_LabeledStatement) {
                 assert.ok(
-                    node.label.name == "input" || node.label.name == "expect" || node.label.name == "expect_exact",
+                    ["input", "expect", "expect_exact", "expect_warnings"].indexOf(node.label.name) >= 0,
                     tmpl("Unsupported label {name} [{line},{col}]", {
                         name: node.label.name,
                         line: node.label.start.line,