-g: debug info, in the compiler written in Finch

DWARF as LLVM metadata: a compile unit, a subprogram per function, a location on every call, a variable
for each local and parameter with types a debugger can open (structs with their fields, arrays and text
as ptr/len/cap, maps, enums with their variants, pointers, fixed arrays). Methods show self.

Use it with -O0, as the docs say: the optimizer inlines the program into main, which has no debug info.
boot.sh builds ten programs with -g -O0 and checks they still behave. 51 passed.

boot/main.fch

@@ -136,6 +136,7 @@ fn main([]str args) -> int {
     out := stem(file)
     outGiven := false
     shared := false
+    debug := false
     opt := "-O2"
     []str extraLibs
     []str extraDirs
@@ -161,8 +162,10 @@ fn main([]str args) -> int {
         } else if a == "-I" && ai + 1 < args.len {
             extraDirs.push(args[ai + 1])
             ai += 1
-        } else if a == "-g" || a == "--target" {
-            print("error: '" + a + "' is not in the compiler written in Finch yet; the C++ one has it (branch before-bootstrap)")
+        } else if a == "-g" {
+            debug = true
+        } else if a == "--target" {
+            print("error: '--target' is not in the compiler written in Finch yet; the C++ one has it (branch before-bootstrap)")
             return 1
         } else if cmd == "run" {
             progArgs.push(a)
@@ -219,7 +222,7 @@ fn main([]str args) -> int {
         print(err)
         return 1
     }
-    ir := gen.generate(loader.progs, loader.files, ci, shared)
+    ir := gen.generate(loader.progs, loader.files, ci, gen.Options(shared: shared, debug: debug, cwd: getenv("PWD")))
     if cmd == "ir" {
         print(ir)
         return 0
@@ -246,6 +249,9 @@ fn main([]str args) -> int {
     if shared {
         sharedFlags = " -shared -fPIC"
     }
+    if debug {
+        sharedFlags = sharedFlags + " -g"      // or clang drops the debug info that is in the IR
+    }
     // the compiler of the IR is always a clang (CC may be gcc, which can't read it); FINCH_CC picks another clang
     cc := getenv("FINCH_CC")
     if cc.len == 0 {