[LLDB][REPL] Change the default tab size

[wallace]

Summary

The REPL has a default tab size of 4 spaces, which seems to be a bit too much. The reason is that the REPL transforms tabs into spaces, and therefore whenever you want to manually deindent, you need to delete at least 4 characters. On the other hand, using 2 as default results in less keystrokes, without hurting readability.

[bulbazord]

I have no problem with this conceptually. I'm not sure if there are any caveats or other things that need to be updated though, so please wait for more input before landing

[JDevlieghere]

+ @aprantl for impact on the Swift REPL

[aprantl]

This should probably be a language-specific setting, but I see no problem in doing it this way right now, since there is practically only one language.
Please update any REPL tests on the Swift branch that need updating when cherry-picking though.

[wallace]

@aprantl, how should I proceed with the swift branch? Should I create a new branch in https://github.com/apple/swift and share it here so it's available for whoever does the merge?

[aprantl]

@aprantl, how should I proceed with the swift branch? Should I create a new branch in https://github.com/apple/swift and share it here so it's available for whoever does the merge?

Actually, I can just cherry-pick it myself, let's not worry about this.

lldb/source/Core/CoreProperties.td

def AutoIndent: Property<"auto-indent", "Boolean">,
     DefaultTrue,
     Desc<"If true, LLDB will auto indent/outdent code. Currently only supported in the REPL (default: true).">;
   def PrintDecls: Property<"print-decls", "Boolean">,
     Global,
     DefaultTrue,
     Desc<"If true, LLDB will print the values of variables declared in an expression. Currently only supported in the REPL (default: true).">;
   def TabSize: Property<"tab-size", "UInt64">,
     Global,
-    DefaultUnsignedValue<4>,
-    Desc<"The tab size to use when indenting code in multi-line input mode (default: 4).">;
+    DefaultUnsignedValue<2>,
+    Desc<"The tab size to use when indenting code in multi-line input mode (default: 2).">;
   def EscapeNonPrintables: Property<"escape-non-printables", "Boolean">,
     Global,
     DefaultTrue,
     Desc<"If true, LLDB will automatically escape non-printable and escape characters when formatting strings.">;
   def FrameFormatUnique: Property<"frame-format-unique", "FormatEntity">,
     Global,
     DefaultStringValue<"frame #${frame.index}: ${ansi.fg.yellow}${frame.pc}${ansi.normal}{ ${module.file.basename}{`${function.name-without-args}{${frame.no-debug}${function.pc-offset}}}}{ at ${ansi.fg.cyan}${line.file.basename}${ansi.normal}:${ansi.fg.yellow}${line.number}${ansi.normal}{:${ansi.fg.yellow}${line.column}${ansi.normal}}}{${function.is-optimized} [opt]}{${frame.is-artificial} [artificial]}\\\\n">,
     Desc<"The default frame format string to use when displaying stack frame information for threads from thread backtrace unique.">;