Merge remote-tracking branch 'upstream/master' into usermarksusermarks

1 files changed, 893 insertions, 556 deletions

diff --git a/src/nvim/diff.c b/src/nvim/diff.c
index 5485d528f7..032de561b3 100644
--- a/src/nvim/diff.c
+++ b/src/nvim/diff.c
@@ -10,9 +10,15 @@
 /// - Use the compiled-in xdiff library.
 /// - Let 'diffexpr' do the work, using files.
 
+#include <assert.h>
+#include <ctype.h>
 #include <inttypes.h>
 #include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
 
+#include "auto/config.h"
 #include "nvim/ascii.h"
 #include "nvim/autocmd.h"
 #include "nvim/buffer.h"
@@ -23,9 +29,15 @@
 #include "nvim/drawscreen.h"
 #include "nvim/eval.h"
 #include "nvim/ex_cmds.h"
+#include "nvim/ex_cmds_defs.h"
 #include "nvim/ex_docmd.h"
+#include "nvim/extmark_defs.h"
 #include "nvim/fileio.h"
 #include "nvim/fold.h"
+#include "nvim/garray.h"
+#include "nvim/gettext.h"
+#include "nvim/globals.h"
+#include "nvim/linematch.h"
 #include "nvim/mark.h"
 #include "nvim/mbyte.h"
 #include "nvim/memline.h"
@@ -35,10 +47,13 @@
 #include "nvim/normal.h"
 #include "nvim/option.h"
 #include "nvim/optionstr.h"
+#include "nvim/os/fs_defs.h"
 #include "nvim/os/os.h"
 #include "nvim/os/shell.h"
 #include "nvim/path.h"
+#include "nvim/pos.h"
 #include "nvim/strings.h"
+#include "nvim/types.h"
 #include "nvim/ui.h"
 #include "nvim/undo.h"
 #include "nvim/vim.h"
@@ -61,10 +76,12 @@ static bool diff_need_update = false;  // ex_diffupdate needs to be called
 #define DIFF_INTERNAL   0x200   // use internal xdiff algorithm
 #define DIFF_CLOSE_OFF  0x400   // diffoff when closing window
 #define DIFF_FOLLOWWRAP 0x800   // follow the wrap option
+#define DIFF_LINEMATCH  0x1000  // match most similar lines within diff
 #define ALL_WHITE_DIFF (DIFF_IWHITE | DIFF_IWHITEALL | DIFF_IWHITEEOL)
 static int diff_flags = DIFF_INTERNAL | DIFF_FILLER | DIFF_CLOSE_OFF;
 
 static long diff_algorithm = 0;
+static int linematch_lines = 0;
 
 #define LBUFLEN 50               // length of line in diff file
 
@@ -74,13 +91,13 @@ static TriState diff_a_works = kNone;
 
 // used for diff input
 typedef struct {
-  char_u *din_fname;   // used for external diff
+  char *din_fname;   // used for external diff
   mmfile_t din_mmfile;  // used for internal diff
 } diffin_T;
 
 // used for diff result
 typedef struct {
-  char_u *dout_fname;  // used for external diff
+  char *dout_fname;  // used for external diff
   garray_T dout_ga;     // used for internal diff
 } diffout_T;
 
@@ -100,6 +117,12 @@ typedef struct {
   int dio_internal;  // using internal diff
 } diffio_T;
 
+typedef enum {
+  DIFF_ED,
+  DIFF_UNIFIED,
+  DIFF_NONE,
+} diffstyle_T;
+
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "diff.c.generated.h"
 #endif
@@ -120,7 +143,7 @@ void diff_buf_delete(buf_T *buf)
         // don't redraw right away, more might change or buffer state
         // is invalid right now
         need_diff_redraw = true;
-        redraw_later(curwin, VALID);
+        redraw_later(curwin, UPD_VALID);
       }
     }
   }
@@ -204,13 +227,7 @@ static void diff_buf_clear(void)
 /// @return Its index or DB_COUNT if not found.
 static int diff_buf_idx(buf_T *buf)
 {
-  int idx;
-  for (idx = 0; idx < DB_COUNT; idx++) {
-    if (curtab->tp_diffbuf[idx] == buf) {
-      break;
-    }
-  }
-  return idx;
+  return diff_buf_idx_tp(buf, curtab);
 }
 
 /// Find buffer "buf" in the list of diff buffers for tab page "tp".
@@ -309,8 +326,6 @@ static void diff_mark_adjust_tp(tabpage_T *tp, int idx, linenr_T line1, linenr_T
   diff_T *dp = tp->tp_first_diff;
 
   linenr_T lnum_deleted = line1;  // lnum of remaining deletion
-  linenr_T n;
-  linenr_T off;
   for (;;) {
     // If the change is after the previous diff block and before the next
     // diff block, thus not touching an existing change, create a new diff
@@ -363,7 +378,7 @@ static void diff_mark_adjust_tp(tabpage_T *tp, int idx, linenr_T line1, linenr_T
     if (last >= line1 - 1) {
       // 6. change below line2: only adjust for amount_after; also when
       // "deleted" became zero when deleted all lines between two diffs.
-      if (dp->df_lnum[idx] - (deleted + inserted != 0) > line2) {
+      if (dp->df_lnum[idx] - (deleted + inserted != 0) > line2 - dp->is_linematched) {
         if (amount_after == 0) {
           // nothing left to change
           break;
@@ -374,7 +389,8 @@ static void diff_mark_adjust_tp(tabpage_T *tp, int idx, linenr_T line1, linenr_T
 
         // 2. 3. 4. 5.: inserted/deleted lines touching this diff.
         if (deleted > 0) {
-          off = 0;
+          linenr_T n;
+          linenr_T off = 0;
           if (dp->df_lnum[idx] >= line1) {
             if (last <= line2) {
               // 4. delete all lines of diff
@@ -454,7 +470,7 @@ static void diff_mark_adjust_tp(tabpage_T *tp, int idx, linenr_T line1, linenr_T
     }
 
     // check if this block touches the previous one, may merge them.
-    if ((dprev != NULL)
+    if ((dprev != NULL) && !dp->is_linematched
         && (dprev->df_lnum[idx] + dprev->df_count[idx] == dp->df_lnum[idx])) {
       int i;
       for (i = 0; i < DB_COUNT; i++) {
@@ -462,9 +478,7 @@ static void diff_mark_adjust_tp(tabpage_T *tp, int idx, linenr_T line1, linenr_T
           dprev->df_count[i] += dp->df_count[i];
         }
       }
-      dprev->df_next = dp->df_next;
-      xfree(dp);
-      dp = dprev->df_next;
+      dp = diff_free(tp, dprev, dp);
     } else {
       // Advance to next entry.
       dprev = dp;
@@ -485,15 +499,7 @@ static void diff_mark_adjust_tp(tabpage_T *tp, int idx, linenr_T line1, linenr_T
     }
 
     if (i == DB_COUNT) {
-      diff_T *dnext = dp->df_next;
-      xfree(dp);
-      dp = dnext;
-
-      if (dprev == NULL) {
-        tp->tp_first_diff = dnext;
-      } else {
-        dprev->df_next = dnext;
-      }
+      dp = diff_free(tp, dprev, dp);
     } else {
       // Advance to next entry.
       dprev = dp;
@@ -523,6 +529,7 @@ static diff_T *diff_alloc_new(tabpage_T *tp, diff_T *dprev, diff_T *dp)
 {
   diff_T *dnew = xmalloc(sizeof(*dnew));
 
+  dnew->is_linematched = false;
   dnew->df_next = dp;
   if (dprev == NULL) {
     tp->tp_first_diff = dnew;
@@ -533,6 +540,20 @@ static diff_T *diff_alloc_new(tabpage_T *tp, diff_T *dprev, diff_T *dp)
   return dnew;
 }
 
+static diff_T *diff_free(tabpage_T *tp, diff_T *dprev, diff_T *dp)
+{
+  diff_T *ret = dp->df_next;
+  xfree(dp);
+
+  if (dprev == NULL) {
+    tp->tp_first_diff = ret;
+  } else {
+    dprev->df_next = ret;
+  }
+
+  return ret;
+}
+
 /// Check if the diff block "dp" can be made smaller for lines at the start and
 /// end that are equal.  Called after inserting lines.
 ///
@@ -573,9 +594,9 @@ static void diff_check_unchanged(tabpage_T *tp, diff_T *dp)
       if (dir == BACKWARD) {
         off_org = dp->df_count[i_org] - 1;
       }
-      char_u *line_org = vim_strsave(ml_get_buf(tp->tp_diffbuf[i_org],
-                                                dp->df_lnum[i_org] + off_org,
-                                                false));
+      char *line_org = xstrdup(ml_get_buf(tp->tp_diffbuf[i_org],
+                                          dp->df_lnum[i_org] + off_org,
+                                          false));
 
       int i_new;
       for (i_new = i_org + 1; i_new < DB_COUNT; i_new++) {
@@ -659,7 +680,7 @@ void diff_redraw(bool dofold)
       continue;
     }
 
-    redraw_later(wp, SOME_VALID);
+    redraw_later(wp, UPD_SOME_VALID);
     if (wp != curwin) {
       wp_other = wp;
     }
@@ -704,16 +725,16 @@ static void clear_diffin(diffin_T *din)
   if (din->din_fname == NULL) {
     XFREE_CLEAR(din->din_mmfile.ptr);
   } else {
-    os_remove((char *)din->din_fname);
+    os_remove(din->din_fname);
   }
 }
 
 static void clear_diffout(diffout_T *dout)
 {
   if (dout->dout_fname == NULL) {
-    ga_clear_strings(&dout->dout_ga);
+    ga_clear(&dout->dout_ga);
   } else {
-    os_remove((char *)dout->dout_fname);
+    os_remove(dout->dout_fname);
   }
 }
 
@@ -723,15 +744,19 @@ static void clear_diffout(diffout_T *dout)
 /// @param din
 ///
 /// @return FAIL for failure.
-static int diff_write_buffer(buf_T *buf, diffin_T *din)
+static int diff_write_buffer(buf_T *buf, mmfile_t *m, linenr_T start, linenr_T end)
 {
-  long len = 0;
+  size_t len = 0;
+
+  if (end < 0) {
+    end = buf->b_ml.ml_line_count;
+  }
 
   // xdiff requires one big block of memory with all the text.
-  for (linenr_T lnum = 1; lnum <= buf->b_ml.ml_line_count; lnum++) {
-    len += (long)STRLEN(ml_get_buf(buf, lnum, false)) + 1;
+  for (linenr_T lnum = start; lnum <= end; lnum++) {
+    len += strlen(ml_get_buf(buf, lnum, false)) + 1;
   }
-  char_u *ptr = try_malloc((size_t)len);
+  char *ptr = try_malloc(len);
   if (ptr == NULL) {
     // Allocating memory failed.  This can happen, because we try to read
     // the whole buffer text into memory.  Set the failed flag, the diff
@@ -745,37 +770,32 @@ static int diff_write_buffer(buf_T *buf, diffin_T *din)
     }
     return FAIL;
   }
-  din->din_mmfile.ptr = (char *)ptr;
-  din->din_mmfile.size = len;
+  m->ptr = ptr;
+  m->size = (long)len;
 
   len = 0;
-  for (linenr_T lnum = 1; lnum <= buf->b_ml.ml_line_count; lnum++) {
-    for (char_u *s = ml_get_buf(buf, lnum, false); *s != NUL;) {
-      if (diff_flags & DIFF_ICASE) {
-        int c;
+  for (linenr_T lnum = start; lnum <= end; lnum++) {
+    char *s = ml_get_buf(buf, lnum, false);
+    if (diff_flags & DIFF_ICASE) {
+      while (*s != NUL) {
         char cbuf[MB_MAXBYTES + 1];
 
-        if (*s == NL) {
-          c = NUL;
-        } else {
-          // xdiff doesn't support ignoring case, fold-case the text.
-          c = utf_ptr2char((char *)s);
-          c = utf_fold(c);
-        }
-        const int orig_len = utfc_ptr2len((char *)s);
-        if (utf_char2bytes(c, (char *)cbuf) != orig_len) {
-          // TODO(Bram): handle byte length difference
-          memmove(ptr + len, s, (size_t)orig_len);
-        } else {
-          memmove(ptr + len, cbuf, (size_t)orig_len);
-        }
+        // xdiff doesn't support ignoring case, fold-case the text.
+        int c = *s == NL ? NUL : utf_fold(utf_ptr2char(s));
+        const int orig_len = utfc_ptr2len(s);
 
+        // TODO(Bram): handle byte length difference
+        char *s1 = (utf_char2bytes(c, cbuf) != orig_len) ? s : cbuf;
+        memmove(ptr + len, s1, (size_t)orig_len);
         s += orig_len;
-        len += orig_len;
-      } else {
-        ptr[len++] = *s == NL ? NUL : *s;
-        s++;
+        len += (size_t)orig_len;
       }
+    } else {
+      size_t slen = strlen(s);
+      memmove(ptr + len, s, slen);
+      // NUL is represented as NL; convert
+      memchrsub(ptr + len, NL, NUL, slen);
+      len += slen;
     }
     ptr[len++] = NL;
   }
@@ -793,17 +813,17 @@ static int diff_write_buffer(buf_T *buf, diffin_T *din)
 static int diff_write(buf_T *buf, diffin_T *din)
 {
   if (din->din_fname == NULL) {
-    return diff_write_buffer(buf, din);
+    return diff_write_buffer(buf, &din->din_mmfile, 1, -1);
   }
 
   // Always use 'fileformat' set to "unix".
-  char_u *save_ff = buf->b_p_ff;
-  buf->b_p_ff = vim_strsave((char_u *)FF_UNIX);
+  char *save_ff = buf->b_p_ff;
+  buf->b_p_ff = xstrdup(FF_UNIX);
   const bool save_cmod_flags = cmdmod.cmod_flags;
   // Writing the buffer is an implementation detail of performing the diff,
   // so it shouldn't update the '[ and '] marks.
   cmdmod.cmod_flags |= CMOD_LOCKMARKS;
-  int r = buf_write(buf, (char *)din->din_fname, NULL,
+  int r = buf_write(buf, din->din_fname, NULL,
                     (linenr_T)1, buf->b_ml.ml_line_count,
                     NULL, false, false, false, true);
   cmdmod.cmod_flags = save_cmod_flags;
@@ -821,7 +841,7 @@ static int diff_write(buf_T *buf, diffin_T *din)
 static void diff_try_update(diffio_T *dio, int idx_orig, exarg_T *eap)
 {
   if (dio->dio_internal) {
-    ga_init(&dio->dio_diff.dout_ga, sizeof(char *), 1000);
+    ga_init(&dio->dio_diff.dout_ga, sizeof(diffhunk_T), 100);
   } else {
     // We need three temp file names.
     dio->dio_orig.din_fname = vim_tempname();
@@ -992,7 +1012,7 @@ static int check_external_diff(diffio_T *diffio)
   TriState ok = kFalse;
   for (;;) {
     ok = kFalse;
-    FILE *fd = os_fopen((char *)diffio->dio_orig.din_fname, "w");
+    FILE *fd = os_fopen(diffio->dio_orig.din_fname, "w");
 
     if (fd == NULL) {
       io_error = true;
@@ -1001,7 +1021,7 @@ static int check_external_diff(diffio_T *diffio)
         io_error = true;
       }
       fclose(fd);
-      fd = os_fopen((char *)diffio->dio_new.din_fname, "w");
+      fd = os_fopen(diffio->dio_new.din_fname, "w");
 
       if (fd == NULL) {
         io_error = true;
@@ -1012,13 +1032,13 @@ static int check_external_diff(diffio_T *diffio)
         fclose(fd);
         fd = NULL;
         if (diff_file(diffio) == OK) {
-          fd = os_fopen((char *)diffio->dio_diff.dout_fname, "r");
+          fd = os_fopen(diffio->dio_diff.dout_fname, "r");
         }
 
         if (fd == NULL) {
           io_error = true;
         } else {
-          char_u linebuf[LBUFLEN];
+          char linebuf[LBUFLEN];
 
           for (;;) {
             // For normal diff there must be a line that contains
@@ -1027,17 +1047,17 @@ static int check_external_diff(diffio_T *diffio)
               break;
             }
 
-            if (STRNCMP(linebuf, "1c1", 3) == 0
-                || STRNCMP(linebuf, "@@ -1 +1 @@", 11) == 0) {
+            if (strncmp(linebuf, "1c1", 3) == 0
+                || strncmp(linebuf, "@@ -1 +1 @@", 11) == 0) {
               ok = kTrue;
             }
           }
           fclose(fd);
         }
-        os_remove((char *)diffio->dio_diff.dout_fname);
-        os_remove((char *)diffio->dio_new.din_fname);
+        os_remove(diffio->dio_diff.dout_fname);
+        os_remove(diffio->dio_new.din_fname);
       }
-      os_remove((char *)diffio->dio_orig.din_fname);
+      os_remove(diffio->dio_orig.din_fname);
     }
 
     // When using 'diffexpr' break here.
@@ -1115,9 +1135,9 @@ static int diff_file_internal(diffio_T *diffio)
 /// @return OK or FAIL
 static int diff_file(diffio_T *dio)
 {
-  char *tmp_orig = (char *)dio->dio_orig.din_fname;
-  char *tmp_new = (char *)dio->dio_new.din_fname;
-  char *tmp_diff = (char *)dio->dio_diff.dout_fname;
+  char *tmp_orig = dio->dio_orig.din_fname;
+  char *tmp_new = dio->dio_new.din_fname;
+  char *tmp_diff = dio->dio_diff.dout_fname;
   if (*p_dex != NUL) {
     // Use 'diffexpr' to generate the diff file.
     eval_diff(tmp_orig, tmp_new, tmp_diff);
@@ -1126,37 +1146,37 @@ static int diff_file(diffio_T *dio)
   // Use xdiff for generating the diff.
   if (dio->dio_internal) {
     return diff_file_internal(dio);
-  } else {
-    const size_t len = (strlen(tmp_orig) + strlen(tmp_new) + strlen(tmp_diff)
-                        + STRLEN(p_srr) + 27);
-    char *const cmd = xmalloc(len);
-
-    // We don't want $DIFF_OPTIONS to get in the way.
-    if (os_getenv("DIFF_OPTIONS")) {
-      os_unsetenv("DIFF_OPTIONS");
-    }
-
-    // Build the diff command and execute it.  Always use -a, binary
-    // differences are of no use.  Ignore errors, diff returns
-    // non-zero when differences have been found.
-    vim_snprintf(cmd, len, "diff %s%s%s%s%s%s%s%s %s",
-                 diff_a_works == kFalse ? "" : "-a ",
-                 "",
-                 (diff_flags & DIFF_IWHITE) ? "-b " : "",
-                 (diff_flags & DIFF_IWHITEALL) ? "-w " : "",
-                 (diff_flags & DIFF_IWHITEEOL) ? "-Z " : "",
-                 (diff_flags & DIFF_IBLANK) ? "-B " : "",
-                 (diff_flags & DIFF_ICASE) ? "-i " : "",
-                 tmp_orig, tmp_new);
-    append_redir(cmd, len, (char *)p_srr, tmp_diff);
-    block_autocmds();  // Avoid ShellCmdPost stuff
-    (void)call_shell((char_u *)cmd,
-                     kShellOptFilter | kShellOptSilent | kShellOptDoOut,
-                     NULL);
-    unblock_autocmds();
-    xfree(cmd);
-    return OK;
   }
+
+  const size_t len = (strlen(tmp_orig) + strlen(tmp_new) + strlen(tmp_diff)
+                      + strlen(p_srr) + 27);
+  char *const cmd = xmalloc(len);
+
+  // We don't want $DIFF_OPTIONS to get in the way.
+  if (os_getenv("DIFF_OPTIONS")) {
+    os_unsetenv("DIFF_OPTIONS");
+  }
+
+  // Build the diff command and execute it.  Always use -a, binary
+  // differences are of no use.  Ignore errors, diff returns
+  // non-zero when differences have been found.
+  vim_snprintf(cmd, len, "diff %s%s%s%s%s%s%s%s %s",
+               diff_a_works == kFalse ? "" : "-a ",
+               "",
+               (diff_flags & DIFF_IWHITE) ? "-b " : "",
+               (diff_flags & DIFF_IWHITEALL) ? "-w " : "",
+               (diff_flags & DIFF_IWHITEEOL) ? "-Z " : "",
+               (diff_flags & DIFF_IBLANK) ? "-B " : "",
+               (diff_flags & DIFF_ICASE) ? "-i " : "",
+               tmp_orig, tmp_new);
+  append_redir(cmd, len, p_srr, tmp_diff);
+  block_autocmds();  // Avoid ShellCmdPost stuff
+  (void)call_shell(cmd,
+                   kShellOptFilter | kShellOptSilent | kShellOptDoOut,
+                   NULL);
+  unblock_autocmds();
+  xfree(cmd);
+  return OK;
 }
 
 /// Create a new version of a file from the current buffer and a diff file.
@@ -1167,10 +1187,10 @@ static int diff_file(diffio_T *dio)
 /// @param eap
 void ex_diffpatch(exarg_T *eap)
 {
-  char_u *buf = NULL;
+  char *buf = NULL;
   win_T *old_curwin = curwin;
   char *newname = NULL;  // name of patched file buffer
-  char_u *esc_name = NULL;
+  char *esc_name = NULL;
 
 #ifdef UNIX
   char *fullname = NULL;
@@ -1178,16 +1198,16 @@ void ex_diffpatch(exarg_T *eap)
 
   // We need two temp file names.
   // Name of original temp file.
-  char_u *tmp_orig = vim_tempname();
+  char *tmp_orig = vim_tempname();
   // Name of patched temp file.
-  char_u *tmp_new = vim_tempname();
+  char *tmp_new = vim_tempname();
 
   if ((tmp_orig == NULL) || (tmp_new == NULL)) {
     goto theend;
   }
 
   // Write the current buffer to "tmp_orig".
-  if (buf_write(curbuf, (char *)tmp_orig, NULL,
+  if (buf_write(curbuf, tmp_orig, NULL,
                 (linenr_T)1, curbuf->b_ml.ml_line_count,
                 NULL, false, false, false, true) == FAIL) {
     goto theend;
@@ -1196,23 +1216,22 @@ void ex_diffpatch(exarg_T *eap)
 #ifdef UNIX
   // Get the absolute path of the patchfile, changing directory below.
   fullname = FullName_save(eap->arg, false);
-  esc_name =
-    vim_strsave_shellescape((char_u *)(fullname != NULL ? fullname : eap->arg), true, true);
+  esc_name = vim_strsave_shellescape(fullname != NULL ? fullname : eap->arg, true, true);
 #else
   esc_name = vim_strsave_shellescape(eap->arg, true, true);
 #endif
-  size_t buflen = STRLEN(tmp_orig) + STRLEN(esc_name) + STRLEN(tmp_new) + 16;
+  size_t buflen = strlen(tmp_orig) + strlen(esc_name) + strlen(tmp_new) + 16;
   buf = xmalloc(buflen);
 
 #ifdef UNIX
-  char_u dirbuf[MAXPATHL];
+  char dirbuf[MAXPATHL];
   // Temporarily chdir to /tmp, to avoid patching files in the current
   // directory when the patch file contains more than one patch.  When we
   // have our own temp dir use that instead, it will be cleaned up when we
   // exit (any .rej files created).  Don't change directory if we can't
   // return to the current.
   if ((os_dirname(dirbuf, MAXPATHL) != OK)
-      || (os_chdir((char *)dirbuf) != 0)) {
+      || (os_chdir(dirbuf) != 0)) {
     dirbuf[0] = NUL;
   } else {
     char *tempdir = vim_gettempdir();
@@ -1227,15 +1246,13 @@ void ex_diffpatch(exarg_T *eap)
   if (*p_pex != NUL) {
     // Use 'patchexpr' to generate the new file.
 #ifdef UNIX
-    eval_patch((char *)tmp_orig,
-               (fullname != NULL ? fullname : eap->arg),
-               (char *)tmp_new);
+    eval_patch(tmp_orig, (fullname != NULL ? fullname : eap->arg), tmp_new);
 #else
-    eval_patch((char *)tmp_orig, (char *)eap->arg, (char *)tmp_new);
+    eval_patch(tmp_orig, eap->arg, tmp_new);
 #endif
   } else {
     // Build the patch command and execute it. Ignore errors.
-    vim_snprintf((char *)buf, buflen, "patch -o %s %s < %s",
+    vim_snprintf(buf, buflen, "patch -o %s %s < %s",
                  tmp_new, tmp_orig, esc_name);
     block_autocmds();  // Avoid ShellCmdPost stuff
     (void)call_shell(buf, kShellOptFilter, NULL);
@@ -1244,7 +1261,7 @@ void ex_diffpatch(exarg_T *eap)
 
 #ifdef UNIX
   if (dirbuf[0] != NUL) {
-    if (os_chdir((char *)dirbuf) != 0) {
+    if (os_chdir(dirbuf) != 0) {
       emsg(_(e_prev_dir));
     }
     shorten_fnames(true);
@@ -1254,20 +1271,20 @@ void ex_diffpatch(exarg_T *eap)
   // Delete any .orig or .rej file created.
   STRCPY(buf, tmp_new);
   STRCAT(buf, ".orig");
-  os_remove((char *)buf);
+  os_remove(buf);
   STRCPY(buf, tmp_new);
   STRCAT(buf, ".rej");
-  os_remove((char *)buf);
+  os_remove(buf);
 
   // Only continue if the output file was created.
   FileInfo file_info;
-  bool info_ok = os_fileinfo((char *)tmp_new, &file_info);
+  bool info_ok = os_fileinfo(tmp_new, &file_info);
   uint64_t filesize = os_fileinfo_size(&file_info);
   if (!info_ok || filesize == 0) {
     emsg(_("E816: Cannot read patch output"));
   } else {
     if (curbuf->b_fname != NULL) {
-      newname = xstrnsave(curbuf->b_fname, STRLEN(curbuf->b_fname) + 4);
+      newname = xstrnsave(curbuf->b_fname, strlen(curbuf->b_fname) + 4);
       STRCAT(newname, ".new");
     }
 
@@ -1277,7 +1294,7 @@ void ex_diffpatch(exarg_T *eap)
     if (win_split(0, (diff_flags & DIFF_VERTICAL) ? WSP_VERT : 0) != FAIL) {
       // Pretend it was a ":split fname" command
       eap->cmdidx = CMD_split;
-      eap->arg = (char *)tmp_new;
+      eap->arg = tmp_new;
       do_exedit(eap, old_curwin);
 
       // check that split worked and editing tmp_new
@@ -1302,12 +1319,12 @@ void ex_diffpatch(exarg_T *eap)
 
 theend:
   if (tmp_orig != NULL) {
-    os_remove((char *)tmp_orig);
+    os_remove(tmp_orig);
   }
   xfree(tmp_orig);
 
   if (tmp_new != NULL) {
-    os_remove((char *)tmp_new);
+    os_remove(tmp_new);
   }
   xfree(tmp_new);
   xfree(newname);
@@ -1334,30 +1351,33 @@ void ex_diffsplit(exarg_T *eap)
   // don't use a new tab page, each tab page has its own diffs
   cmdmod.cmod_tab = 0;
 
-  if (win_split(0, (diff_flags & DIFF_VERTICAL) ? WSP_VERT : 0) != FAIL) {
-    // Pretend it was a ":split fname" command
-    eap->cmdidx = CMD_split;
-    curwin->w_p_diff = true;
-    do_exedit(eap, old_curwin);
-
-    // split must have worked
-    if (curwin != old_curwin) {
-      // Set 'diff', 'scrollbind' on and 'wrap' off.
-      diff_win_options(curwin, true);
-      if (win_valid(old_curwin)) {
-        diff_win_options(old_curwin, true);
+  if (win_split(0, (diff_flags & DIFF_VERTICAL) ? WSP_VERT : 0) == FAIL) {
+    return;
+  }
 
-        if (bufref_valid(&old_curbuf)) {
-          // Move the cursor position to that of the old window.
-          curwin->w_cursor.lnum = diff_get_corresponding_line(old_curbuf.br_buf,
-                                                              old_curwin->w_cursor.lnum);
-        }
-      }
-      // Now that lines are folded scroll to show the cursor at the same
-      // relative position.
-      scroll_to_fraction(curwin, curwin->w_height);
+  // Pretend it was a ":split fname" command
+  eap->cmdidx = CMD_split;
+  curwin->w_p_diff = true;
+  do_exedit(eap, old_curwin);
+
+  if (curwin == old_curwin) {  // split didn't work
+    return;
+  }
+
+  // Set 'diff', 'scrollbind' on and 'wrap' off.
+  diff_win_options(curwin, true);
+  if (win_valid(old_curwin)) {
+    diff_win_options(old_curwin, true);
+
+    if (bufref_valid(&old_curbuf)) {
+      // Move the cursor position to that of the old window.
+      curwin->w_cursor.lnum = diff_get_corresponding_line(old_curbuf.br_buf,
+                                                          old_curwin->w_cursor.lnum);
     }
   }
+  // Now that lines are folded scroll to show the cursor at the same
+  // relative position.
+  scroll_to_fraction(curwin, curwin->w_height);
 }
 
 // Set options to show diffs for the current window.
@@ -1374,7 +1394,7 @@ static void set_diff_option(win_T *wp, int value)
   curwin = wp;
   curbuf = curwin->w_buffer;
   curbuf->b_ro_locked++;
-  set_option_value("diff", (long)value, NULL, OPT_LOCAL);
+  set_option_value_give_err("diff", (long)value, NULL, OPT_LOCAL);
   curbuf->b_ro_locked--;
   curwin = old_curwin;
   curbuf = curwin->w_buffer;
@@ -1413,7 +1433,7 @@ void diff_win_options(win_T *wp, int addbuf)
     if (wp->w_p_diff_saved) {
       free_string_option(wp->w_p_fdm_save);
     }
-    wp->w_p_fdm_save = vim_strsave(wp->w_p_fdm);
+    wp->w_p_fdm_save = xstrdup(wp->w_p_fdm);
   }
   set_string_option_direct_in_win(wp, "fdm", -1, "diff", OPT_LOCAL | OPT_FREE, 0);
 
@@ -1424,12 +1444,12 @@ void diff_win_options(win_T *wp, int addbuf)
     if (wp->w_p_diff_saved) {
       free_string_option(wp->w_p_fdc_save);
     }
-    wp->w_p_fdc_save = vim_strsave(wp->w_p_fdc);
+    wp->w_p_fdc_save = xstrdup(wp->w_p_fdc);
   }
   free_string_option(wp->w_p_fdc);
-  wp->w_p_fdc = (char_u *)xstrdup("2");
+  wp->w_p_fdc = xstrdup("2");
   assert(diff_foldcolumn >= 0 && diff_foldcolumn <= 9);
-  snprintf((char *)wp->w_p_fdc, STRLEN(wp->w_p_fdc) + 1, "%d", diff_foldcolumn);
+  snprintf(wp->w_p_fdc, strlen(wp->w_p_fdc) + 1, "%d", diff_foldcolumn);
   wp->w_p_fen = true;
   wp->w_p_fdl = 0;
   foldUpdateAll(wp);
@@ -1448,7 +1468,7 @@ void diff_win_options(win_T *wp, int addbuf)
   if (addbuf) {
     diff_buf_add(wp->w_buffer);
   }
-  redraw_later(wp, NOT_VALID);
+  redraw_later(wp, UPD_NOT_VALID);
 }
 
 /// Set options not to show diffs.  For the current window or all windows.
@@ -1480,11 +1500,9 @@ void ex_diffoff(exarg_T *eap)
           }
         }
         free_string_option(wp->w_p_fdm);
-        wp->w_p_fdm = vim_strsave(*wp->w_p_fdm_save
-                                  ? wp->w_p_fdm_save
-                                  : (char_u *)"manual");
+        wp->w_p_fdm = xstrdup(*wp->w_p_fdm_save ? wp->w_p_fdm_save : "manual");
         free_string_option(wp->w_p_fdc);
-        wp->w_p_fdc = vim_strsave(wp->w_p_fdc_save);
+        wp->w_p_fdc = xstrdup(*wp->w_p_fdc_save ? wp->w_p_fdc_save : "0");
 
         if (wp->w_p_fdl == 0) {
           wp->w_p_fdl = wp->w_p_fdl_save;
@@ -1528,210 +1546,219 @@ void ex_diffoff(exarg_T *eap)
   }
 }
 
-/// Read the diff output and add each entry to the diff list.
-///
-/// @param idx_orig idx of original file
-/// @param idx_new idx of new file
-/// @dout diff output
-static void diff_read(int idx_orig, int idx_new, diffio_T *dio)
+static bool extract_hunk_internal(diffout_T *dout, diffhunk_T *hunk, int *line_idx)
 {
-  FILE *fd = NULL;
-  int line_idx = 0;
-  diff_T *dprev = NULL;
-  diff_T *dp = curtab->tp_first_diff;
-  diff_T *dn, *dpl;
-  diffout_T *dout = &dio->dio_diff;
-  char_u linebuf[LBUFLEN];  // only need to hold the diff line
-  char_u *line;
-  linenr_T off;
-  int i;
-  int notset = true;  // block "*dp" not set yet
-  diffhunk_T *hunk = NULL;  // init to avoid gcc warning
-  enum {
-    DIFF_ED,
-    DIFF_UNIFIED,
-    DIFF_NONE,
-  } diffstyle = DIFF_NONE;
-
-  if (dout->dout_fname == NULL) {
-    diffstyle = DIFF_UNIFIED;
-  } else {
-    fd = os_fopen((char *)dout->dout_fname, "r");
-    if (fd == NULL) {
-      emsg(_("E98: Cannot read diff output"));
-      return;
-    }
-  }
-
-  if (!dio->dio_internal) {
-    hunk = xmalloc(sizeof(*hunk));
+  bool eof = *line_idx >= dout->dout_ga.ga_len;
+  if (!eof) {
+    *hunk = ((diffhunk_T *)dout->dout_ga.ga_data)[(*line_idx)++];
   }
+  return eof;
+}
 
+// Extract hunk by parsing the diff output from file and calculate the diffstyle.
+static bool extract_hunk(FILE *fd, diffhunk_T *hunk, diffstyle_T *diffstyle)
+{
   for (;;) {
-    if (dio->dio_internal) {
-      if (line_idx >= dout->dout_ga.ga_len) {
-        break;      // did last line
-      }
-      hunk = ((diffhunk_T **)dout->dout_ga.ga_data)[line_idx++];
-    } else {
-      if (fd == NULL) {
-        if (line_idx >= dout->dout_ga.ga_len) {
-          break;      // did last line
-        }
-        line = ((char_u **)dout->dout_ga.ga_data)[line_idx++];
+    char line[LBUFLEN];  // only need to hold the diff line
+    if (vim_fgets(line, LBUFLEN, fd)) {
+      return true;  // end of file
+    }
+
+    if (*diffstyle == DIFF_NONE) {
+      // Determine diff style.
+      // ed like diff looks like this:
+      // {first}[,{last}]c{first}[,{last}]
+      // {first}a{first}[,{last}]
+      // {first}[,{last}]d{first}
+      //
+      // unified diff looks like this:
+      // --- file1       2018-03-20 13:23:35.783153140 +0100
+      // +++ file2       2018-03-20 13:23:41.183156066 +0100
+      // @@ -1,3 +1,5 @@
+      if (isdigit((uint8_t)(*line))) {
+        *diffstyle = DIFF_ED;
+      } else if ((strncmp(line, "@@ ", 3) == 0)) {
+        *diffstyle = DIFF_UNIFIED;
+      } else if ((strncmp(line, "--- ", 4) == 0)  // -V501
+                 && (vim_fgets(line, LBUFLEN, fd) == 0)  // -V501
+                 && (strncmp(line, "+++ ", 4) == 0)
+                 && (vim_fgets(line, LBUFLEN, fd) == 0)  // -V501
+                 && (strncmp(line, "@@ ", 3) == 0)) {
+        *diffstyle = DIFF_UNIFIED;
       } else {
-        if (vim_fgets(linebuf, LBUFLEN, fd)) {
-          break;      // end of file
-        }
-        line = linebuf;
-      }
-
-      if (diffstyle == DIFF_NONE) {
-        // Determine diff style.
-        // ed like diff looks like this:
-        // {first}[,{last}]c{first}[,{last}]
-        // {first}a{first}[,{last}]
-        // {first}[,{last}]d{first}
-        //
-        // unified diff looks like this:
-        // --- file1       2018-03-20 13:23:35.783153140 +0100
-        // +++ file2       2018-03-20 13:23:41.183156066 +0100
-        // @@ -1,3 +1,5 @@
-        if (isdigit(*line)) {
-          diffstyle = DIFF_ED;
-        } else if ((STRNCMP(line, "@@ ", 3) == 0)) {
-          diffstyle = DIFF_UNIFIED;
-        } else if ((STRNCMP(line, "--- ", 4) == 0)  // -V501
-                   && (vim_fgets(linebuf, LBUFLEN, fd) == 0)  // -V501
-                   && (STRNCMP(line, "+++ ", 4) == 0)
-                   && (vim_fgets(linebuf, LBUFLEN, fd) == 0)  // -V501
-                   && (STRNCMP(line, "@@ ", 3) == 0)) {
-          diffstyle = DIFF_UNIFIED;
-        } else {
-          // Format not recognized yet, skip over this line.  Cygwin diff
-          // may put a warning at the start of the file.
-          continue;
-        }
+        // Format not recognized yet, skip over this line.  Cygwin diff
+        // may put a warning at the start of the file.
+        continue;
       }
+    }
 
-      if (diffstyle == DIFF_ED) {
-        if (!isdigit(*line)) {
-          continue;   // not the start of a diff block
-        }
-        if (parse_diff_ed(line, hunk) == FAIL) {
-          continue;
-        }
-      } else {
-        assert(diffstyle == DIFF_UNIFIED);
-        if (STRNCMP(line, "@@ ", 3) != 0) {
-          continue;   // not the start of a diff block
-        }
-        if (parse_diff_unified(line, hunk) == FAIL) {
-          continue;
-        }
+    if (*diffstyle == DIFF_ED) {
+      if (!isdigit((uint8_t)(*line))) {
+        continue;   // not the start of a diff block
+      }
+      if (parse_diff_ed(line, hunk) == FAIL) {
+        continue;
+      }
+    } else {
+      assert(*diffstyle == DIFF_UNIFIED);
+      if (strncmp(line, "@@ ", 3) != 0) {
+        continue;   // not the start of a diff block
+      }
+      if (parse_diff_unified(line, hunk) == FAIL) {
+        continue;
       }
     }
 
-    // Go over blocks before the change, for which orig and new are equal.
-    // Copy blocks from orig to new.
-    while (dp != NULL
-           && hunk->lnum_orig > dp->df_lnum[idx_orig] + dp->df_count[idx_orig]) {
-      if (notset) {
-        diff_copy_entry(dprev, dp, idx_orig, idx_new);
-      }
-      dprev = dp;
-      dp = dp->df_next;
-      notset = true;
+    // Successfully parsed diff output, can return
+    return false;
+  }
+}
+
+static void process_hunk(diff_T **dpp, diff_T **dprevp, int idx_orig, int idx_new, diffhunk_T *hunk,
+                         bool *notsetp)
+{
+  diff_T *dp = *dpp;
+  diff_T *dprev = *dprevp;
+
+  // Go over blocks before the change, for which orig and new are equal.
+  // Copy blocks from orig to new.
+  while (dp != NULL
+         && hunk->lnum_orig > dp->df_lnum[idx_orig] + dp->df_count[idx_orig]) {
+    if (*notsetp) {
+      diff_copy_entry(dprev, dp, idx_orig, idx_new);
     }
+    dprev = dp;
+    dp = dp->df_next;
+    *notsetp = true;
+  }
 
-    if ((dp != NULL)
-        && (hunk->lnum_orig <= dp->df_lnum[idx_orig] + dp->df_count[idx_orig])
-        && (hunk->lnum_orig + hunk->count_orig >= dp->df_lnum[idx_orig])) {
-      // New block overlaps with existing block(s).
-      // First find last block that overlaps.
-      for (dpl = dp; dpl->df_next != NULL; dpl = dpl->df_next) {
-        if (hunk->lnum_orig + hunk->count_orig < dpl->df_next->df_lnum[idx_orig]) {
-          break;
-        }
+  if ((dp != NULL)
+      && (hunk->lnum_orig <= dp->df_lnum[idx_orig] + dp->df_count[idx_orig])
+      && (hunk->lnum_orig + hunk->count_orig >= dp->df_lnum[idx_orig])) {
+    // New block overlaps with existing block(s).
+    // First find last block that overlaps.
+    diff_T *dpl;
+    for (dpl = dp; dpl->df_next != NULL; dpl = dpl->df_next) {
+      if (hunk->lnum_orig + hunk->count_orig < dpl->df_next->df_lnum[idx_orig]) {
+        break;
       }
+    }
 
-      // If the newly found block starts before the old one, set the
-      // start back a number of lines.
-      off = dp->df_lnum[idx_orig] - hunk->lnum_orig;
+    // If the newly found block starts before the old one, set the
+    // start back a number of lines.
+    linenr_T off = dp->df_lnum[idx_orig] - hunk->lnum_orig;
 
-      if (off > 0) {
-        for (i = idx_orig; i < idx_new; i++) {
-          if (curtab->tp_diffbuf[i] != NULL) {
-            dp->df_lnum[i] -= off;
-          }
-        }
-        dp->df_lnum[idx_new] = hunk->lnum_new;
-        dp->df_count[idx_new] = (linenr_T)hunk->count_new;
-      } else if (notset) {
-        // new block inside existing one, adjust new block
-        dp->df_lnum[idx_new] = hunk->lnum_new + off;
-        dp->df_count[idx_new] = (linenr_T)hunk->count_new - off;
-      } else {
-        // second overlap of new block with existing block
-        dp->df_count[idx_new] += (linenr_T)hunk->count_new - (linenr_T)hunk->count_orig
-                                 + dpl->df_lnum[idx_orig] +
-                                 dpl->df_count[idx_orig]
-                                 - (dp->df_lnum[idx_orig] +
-                                    dp->df_count[idx_orig]);
-      }
-
-      // Adjust the size of the block to include all the