assert_writeln_magic: Report filename on error (instead of magic.d) (#3227)

* assert_writeln_magic: Report filename on error (instead of `magic.d`)

Pass the current file path to libdparse s.t. error messages point to the
actual file instead of `magic.d`.

* preprocessor: Ensure that error messages are not interleaved

Using a single call ensures that parallel builds won't mess up the output

Author: MoonlightSentinel

ddoc/source/assert_writeln_magic.d

@@ -178,7 +178,7 @@ private:
     Out fl;
 }
 
-void parseString(Visitor)(ubyte[] sourceCode, Visitor visitor)
+void parseString(Visitor)(const string filepath, ubyte[] sourceCode, Visitor visitor)
 {
     import dparse.lexer;
     import dparse.parser : parseModule, ParserConfig;
@@ -189,28 +189,28 @@ void parseString(Visitor)(ubyte[] sourceCode, Visitor visitor)
     const(Token)[] tokens = getTokensForParser(sourceCode, config, &cache).array;
 
     RollbackAllocator rba;
-    auto m = parseModule(ParserConfig(tokens, "magic.d", &rba));
+    auto m = parseModule(ParserConfig(tokens, filepath, &rba));
     visitor.visit(m);
 }
 
-private auto assertWritelnModuleImpl(string fileText)
+private auto assertWritelnModuleImpl(const string filepath, string fileText)
 {
     import std.string : representation;
     auto fl = FileLines(fileText);
     scope visitor = new TestVisitor!(typeof(fl))(fl);
     // libdparse doesn't allow to work on immutable source code
-    parseString(cast(ubyte[]) fileText.representation, visitor);
+    parseString(filepath, cast(ubyte[]) fileText.representation, visitor);
     return fl;
 }
 
-auto assertWritelnModule(string fileText)
+auto assertWritelnModule(const string filepath, string fileText)
 {
-    return assertWritelnModuleImpl(fileText).buildLines;
+    return assertWritelnModuleImpl(filepath, fileText).buildLines;
 }
-auto assertWritelnBlock(string fileText)
+auto assertWritelnBlock(const string filepath, string fileText)
 {
     auto source = "unittest{\n" ~ fileText ~ "}\n";
-    auto fl = assertWritelnModuleImpl(source);
+    auto fl = assertWritelnModuleImpl(filepath, source);
     auto app = appender!string;
     foreach (line; fl.lines[1 .. $ - 2])
     {
@@ -275,7 +275,7 @@ version(unittest)
         import std.string : representation;
         auto mock = FileLinesMock(sourceCode.split("\n"));
         scope visitor = new TestVisitor!(typeof(mock))(mock);
-        parseString(sourceCode.representation.dup, visitor);
+        parseString("unittest.d", sourceCode.representation.dup, visitor);
         return mock;
     }
 }

ddoc/source/preprocessor.d

@@ -66,7 +66,7 @@ All unknown options are passed to the compiler.
 
     // Phobos index.d should have been named index.dd
     if (inputFile.endsWith(".d") && !inputFile.endsWith("index.d"))
-        text = assertWritelnModule(text);
+        text = assertWritelnModule(inputFile, text);
 
     string[string] macros;
     macros["SRC_FILENAME"] = "%s\n".format(inputFile.buildNormalizedPath);
@@ -114,10 +114,13 @@ auto compile(R)(R buffer, string[] arguments, string inputFile, string[string] m
     auto ret = execute(args);
     if (ret.status != 0)
     {
-        stderr.writeln("File content:");
-        stderr.writeln(buffer);
-        stderr.writeln("----------------------------------------");
-        stderr.writeln(ret.output);
+        stderr.writeln(
+            "\n------------- File content -------------\n",
+            buffer,
+            "\n------------ Compiler output -----------\n",
+            ret.output,
+            "\n----------------------------------------\n",
+        );
     }
     return ret.status;
 }

dpl-docs/source/ddox_main.d

@@ -129,7 +129,7 @@ int cmdFilterDocs(string[] args)
 						writefln("Warning: Cannot add documented unit test %s to %s, which is not documented.", name, last_decl["name"].opt!string);
 					} else {
 					    import assert_writeln_magic;
-                        auto rewrittenSource = assertWritelnBlock(source);
+                        auto rewrittenSource = assertWritelnBlock(mod["file"].get!string(), source);
                         last_decl["comment"] ~= format("Example:\n%s$(DDOX_UNITTEST_HEADER %s)\n---\n%s\n---\n$(DDOX_UNITTEST_FOOTER %s)\n", comment.strip, name, rewrittenSource, name);
 					}
 				} catch (Exception e) {