run: capture error messages from panics

Capture error messages from panic. I'm not 100% sure that this is the
right course of action. It might be better to treat panics as successes,
because non-zero exit status from go run are generally discarded except
for compiler errors. This change is inconsistent with that fact and may
lead people to expect that non-zero exit statuses from the command being
run should always populate the quickfix list.

Fixes fatih#2328

autoload/go/cmd.vim

@@ -349,8 +349,39 @@ function! go#cmd#Generate(bang, ...) abort
 endfunction
 
 function! s:runerrorformat()
-  let l:panicaddress = "%\\t%#%f:%l +0x%[0-9A-Fa-f]%\\+"
-  let l:errorformat = '%A' . l:panicaddress . "," . &errorformat
+  let goroot = go#util#goroot()
+
+  let stdlibaddress = "%\\t" . goroot . "%\\f%\\+:%\\d%\\+ +0x%[0-9A-Fa-f]%\\+"
+
+  " panicaddress and readyaddress are identical except for
+  " panicaddress sets the filename and line number.
+  let l:panicaddress = '%\\t%f:%l%\\%( +0x%[0-9A-Fa-f]%\\+%\\)%\\='
+  let l:readyaddress = '%\\t%\\f%\\+:%\\d%\\+%\\%( +0x%[0-9A-Fa-f]%\\+%\\)%\\='
+  " stdlib address is identical to readyaddress, except it matches files
+  " inside GOROOT.
+  let l:stdlibaddress = '%\\t' . goroot . '%\\f%\\+:%\\d%\\+%\\%( +0x%[0-9A-Fa-f]%\\+%\\)%\\='
+
+  let l:errorformat = ''
+  let l:errorformat .= '%-Cexit status 2'
+  let l:errorformat .= ",%-C" . stdlibaddress
+  " Match address lines in the first matching goroutine. This means the panic
+  " message will only be shown as the error message in the first address of
+  " the running goroutine's stack.
+  let l:errorformat .= ',%Z' . l:panicaddress
+
+  " Match and ignore panic address without being part of a multi-line message.
+  " This is to catch those lines that come after the top most non-standard
+  " library line in stack traces.
+  let l:errorformat .= ",%-G" . l:panicaddress
+
+  " Match and discard empty lines in a multi-line message.
+  let l:errorformat .= ',%-C'
+  " Match and ignore the goroutine lines.
+  let l:errorformat .= ',%-Cgoroutine %\\d%\\+%.%#:'
+  " Match and discard lines containing function names in multi-line messages.
+  let l:errorformat .= ',%-C%.%#(%\\%(%\\.%\\.%\\.%\\)%\\=)'
+  let l:errorformat .= ',%+Epanic: %m'
+  let l:errorformat .= "," . &errorformat
   return l:errorformat
 endfunction
 

autoload/go/cmd_test.vim

@@ -31,6 +31,22 @@ func! Test_GoBuildErrors()
   endtry
 endfunc
 
+func! Test_GoRunPanic()
+  let l:filename = 'cmd/run/panic/panic.go'
+  let l:tmp = gotest#load_fixture(l:filename)
+
+  let expected = [
+        \ {'lnum': 9, 'bufnr': bufnr('%'), 'col': 0, 'valid': 1, 'vcol': 0, 'nr': -1, 'type': 'E', 'pattern': '', 'text': 'panic: quux'}
+      \ ]
+  try
+    call go#cmd#Run(0)
+    let l:actual = getqflist()
+    call gotest#assert_quickfix(l:actual, l:expected)
+  finally
+    call delete(l:tmp, 'rf')
+  endtry
+endfunc
+
 " restore Vi compatibility settings
 let &cpo = s:cpo_save
 unlet s:cpo_save

autoload/go/complete_test.vim

@@ -9,17 +9,17 @@ func! Test_GetInfo_gopls()
 endfunction
 
 func! s:getinfo()
-    let l:filename = 'complete/complete.go'
-    let l:tmp = gotest#load_fixture(l:filename)
-    try
-      call cursor(8, 3)
+  let l:filename = 'complete/complete.go'
+  let l:tmp = gotest#load_fixture(l:filename)
+  try
+    call cursor(8, 3)
 
-      let expected = 'func Example(s string)'
-      let actual = go#complete#GetInfo()
-      call assert_equal(expected, actual)
-    finally
-      call delete(l:tmp, 'rf')
-    endtry
+    let expected = 'func Example(s string)'
+    let actual = go#complete#GetInfo()
+    call assert_equal(expected, actual)
+  finally
+    call delete(l:tmp, 'rf')
+  endtry
 endfunction
 
 " restore Vi compatibility settings

autoload/go/test-fixtures/cmd/run/panic/panic.go

@@ -0,0 +1,15 @@
+package main
+
+import (
+	"errors"
+	"fmt"
+)
+
+func quux() {
+	panic(errors.New("quux"))
+}
+
+func main() {
+	quux()
+	fmt.Println("vim-go")
+}