Prevent empty statements at the end of --eval or --loop code

rdmd.d

@@ -17,7 +17,7 @@
 import std.algorithm, std.array, core.stdc.stdlib, std.datetime,
     std.digest.md, std.exception, std.file, std.getopt,
     std.parallelism, std.path, std.process, std.range, std.regex,
-    std.stdio, std.string, std.typetuple;
+    std.stdio, std.string, std.typecons, std.typetuple;
 
 version (Posix)
 {
@@ -180,18 +180,14 @@ int main(string[] args)
     {
         enforce(programPos == args.length, "Cannot have both --loop and a " ~
                 "program file ('" ~ args[programPos] ~ "').");
-        root = makeEvalFile(importWorld ~ "void main(char[][] args) { "
-                ~ "foreach (line; std.stdio.stdin.byLine()) {\n"
-                ~ std.string.join(loop, "\n")
-                ~ ";\n} }");
+        root = makeEvalFile(makeEvalCode(loop, Yes.loop));
         argsBeforeProgram ~= "-d";
     }
     else if (eval.ptr)
     {
         enforce(programPos == args.length, "Cannot have both --eval and a " ~
                 "program file ('" ~ args[programPos] ~ "').");
-        root = makeEvalFile(importWorld ~ "void main(char[][] args) {\n"
-                ~ std.string.join(eval, "\n") ~ ";\n}");
+        root = makeEvalFile(makeEvalCode(eval, No.loop));
         argsBeforeProgram ~= "-d";
     }
     else if (programPos < args.length)
@@ -839,6 +835,101 @@ import std.stdio, std.algorithm, std.array, std.ascii, std.base64,
     std.zlib;
 ";
 
+/**
+Joins together the code provided via an `--eval` or `--loop`
+flag, ensuring a trailing `;` is added if not already provided
+by the user
+
+Params:
+    eval = array of strings generated by the `--eval`
+           or `--loop` rdmd flags
+
+Returns:
+    string of code to be evaluated, corresponding to the
+    inner code of either the program or the loop
+*/
+string innerEvalCode(string[] eval)
+{
+    import std.string : join, stripRight;
+    // assumeSafeAppend just to avoid unnecessary reallocation
+    string code = eval.join("\n").stripRight.assumeSafeAppend;
+    if (code.length > 0 && code[$ - 1] != ';')
+        code ~= ';';
+    return code;
+}
+
+unittest
+{
+    assert(innerEvalCode([`writeln("Hello!")`]) == `writeln("Hello!");`);
+    assert(innerEvalCode([`writeln("Hello!");`]) == `writeln("Hello!");`);
+
+    // test with trailing whitespace
+    assert(innerEvalCode([`writeln("Hello!")  `]) == `writeln("Hello!");`);
+    assert(innerEvalCode([`writeln("Hello!");  `]) == `writeln("Hello!");`);
+
+    // test with multiple entries
+    assert(innerEvalCode([`writeln("Hello!");  `, `writeln("You!")  `])
+           == "writeln(\"Hello!\");  \nwriteln(\"You!\");");
+    assert(innerEvalCode([`writeln("Hello!");  `, `writeln("You!"); `])
+           == "writeln(\"Hello!\");  \nwriteln(\"You!\");");
+}
+
+/**
+Formats the code provided via `--eval` or `--loop` flags into a
+string of complete program code that can be written to a file
+and then compiled
+
+Params:
+    eval = array of strings generated by the `--eval` or
+           `--loop` rdmd flags
+    loop = set to `Yes.loop` if this code comes from a
+           `--loop` flag, `No.loop` if it comes from an
+           `--eval` flag
+
+Returns:
+    string of code to be evaluated, corresponding to the
+    inner code of either the program or the loop
+*/
+string makeEvalCode(string[] eval, Flag!"loop" loop)
+{
+    import std.format : format;
+    immutable codeFormat = importWorld
+        ~ "void main(char[][] args) {%s%s\n%s}";
+
+    immutable innerCodeOpening =
+        loop ? " foreach (line; std.stdio.stdin.byLine()) {\n"
+             : "\n";
+
+    immutable innerCodeClosing = loop ? "} " : "";
+
+    return format(codeFormat,
+                  innerCodeOpening,
+                  innerEvalCode(eval),
+                  innerCodeClosing);
+}
+
+unittest
+{
+    // innerEvalCode already tests the cases for different
+    // contents in `eval` array, so let's focus on testing
+    // the difference based on the `loop` flag
+    assert(makeEvalCode([`writeln("Hello!") `], No.loop) ==
+           importWorld
+           ~ "void main(char[][] args) {\n"
+           ~ "writeln(\"Hello!\");\n}");
+
+    assert(makeEvalCode([`writeln("What!"); `], No.loop) ==
+           importWorld
+           ~ "void main(char[][] args) {\n"
+           ~ "writeln(\"What!\");\n}");
+
+    assert(makeEvalCode([`writeln("Loop!") ; `], Yes.loop) ==
+           importWorld
+           ~ "void main(char[][] args) { "
+           ~ "foreach (line; std.stdio.stdin.byLine()) {\n"
+           ~ "writeln(\"Loop!\") ;\n} }");
+}
+
 string makeEvalFile(string todo)
 {
     auto pathname = myOwnTmpDir;