go/types, types2: avoid sorting all errors when matching errors

Sorting is only needed if there are multiple matching errors on
the same line. Instead, in that rare case, select the error that
is closest.

Follow-up on CL 456137.

Change-Id: Ia2056b21c629f3a42495e32de89607fbefb82fa7
Reviewed-on: https://go-review.googlesource.com/c/go/+/456335
Run-TryBot: Robert Griesemer <gri@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>
Reviewed-by: Robert Griesemer <gri@google.com>
Auto-Submit: Robert Griesemer <gri@google.com>

diff --git a/src/cmd/compile/internal/types2/check_test.go b/src/cmd/compile/internal/types2/check_test.go
index 0f97fe968054bf7a8c9e5090f8e6b5877b1f250d..611466ba01e5579ff4ba8daaecc4a17ef324b7dc 100644 (file)
--- a/src/cmd/compile/internal/types2/check_test.go
+++ b/src/cmd/compile/internal/types2/check_test.go
@@ -31,7 +31,6 @@ import (
        "os"
        "path/filepath"
        "regexp"
-       "sort"
        "strings"
        "testing"
 
@@ -68,8 +67,8 @@ func unpackError(err error) (syntax.Pos, string) {
        }
 }
 
-// delta returns the absolute difference between x and y.
-func delta(x, y uint) uint {
+// absDiff returns the absolute difference between x and y.
+func absDiff(x, y uint) uint {
        if x < y {
                return y - x
        }
@@ -165,13 +164,6 @@ func testFiles(t *testing.T, filenames []string, colDelta uint, manual bool) {
                return
        }
 
-       // sort errlist in source order
-       sort.Slice(errlist, func(i, j int) bool {
-               pi, _ := unpackError(errlist[i])
-               pj, _ := unpackError(errlist[j])
-               return pi.Cmp(pj) < 0
-       })
-
        // collect expected errors
        errmap := make(map[string]map[uint][]syntax.Error)
        for _, filename := range filenames {
@@ -187,6 +179,7 @@ func testFiles(t *testing.T, filenames []string, colDelta uint, manual bool) {
        }
 
        // match against found errors
+       var indices []int // list indices of matching errors, reused for each error
        for _, err := range errlist {
                gotPos, gotMsg := unpackError(err)
 
@@ -199,8 +192,8 @@ func testFiles(t *testing.T, filenames []string, colDelta uint, manual bool) {
                        errList = filemap[line]
                }
 
-               // one of errors in errList should match the current error
-               index := -1 // errList index of matching message, if any
+               // At least one of the errors in errList should match the current error.
+               indices = indices[:0]
                for i, want := range errList {
                        pattern := strings.TrimSpace(want.Msg[len(" ERROR "):])
                        if n := len(pattern); n >= 2 && pattern[0] == '"' && pattern[n-1] == '"' {
@@ -212,19 +205,27 @@ func testFiles(t *testing.T, filenames []string, colDelta uint, manual bool) {
                                continue
                        }
                        if rx.MatchString(gotMsg) {
-                               index = i
-                               break
+                               indices = append(indices, i)
                        }
                }
-               if index < 0 {
+               if len(indices) == 0 {
                        t.Errorf("%s: no error expected: %q", gotPos, gotMsg)
                        continue
                }
+               // len(indices) > 0
+
+               // If there are multiple matching errors, select the one with the closest column position.
+               index := -1 // index of matching error
+               var delta uint
+               for _, i := range indices {
+                       if d := absDiff(gotPos.Col(), errList[i].Pos.Col()); index < 0 || d < delta {
+                               index, delta = i, d
+                       }
+               }
 
-               // column position must be within expected colDelta
-               want := errList[index]
-               if delta(gotPos.Col(), want.Pos.Col()) > colDelta {
-                       t.Errorf("%s: got col = %d; want %d", gotPos, gotPos.Col(), want.Pos.Col())
+               // The closest column position must be within expected colDelta.
+               if delta > colDelta {
+                       t.Errorf("%s: got col = %d; want %d", gotPos, gotPos.Col(), errList[index].Pos.Col())
                }
 
                // eliminate from errList

diff --git a/src/go/types/check_test.go b/src/go/types/check_test.go
index 81736f6623485c7d0a946858c97b796c6b82f7da..4d27f3629ad6e044055d2d44cce3f11a6a73efea 100644 (file)
--- a/src/go/types/check_test.go
+++ b/src/go/types/check_test.go
@@ -36,7 +36,6 @@ import (
        "path/filepath"
        "reflect"
        "regexp"
-       "sort"
        "strings"
        "testing"
 
@@ -82,8 +81,8 @@ func unpackError(fset *token.FileSet, err error) (token.Position, string) {
        panic("unreachable")
 }
 
-// delta returns the absolute difference between x and y.
-func delta(x, y int) int {
+// absDiff returns the absolute difference between x and y.
+func absDiff(x, y int) int {
        if x < y {
                return y - x
        }
@@ -183,20 +182,6 @@ func testFiles(t *testing.T, sizes Sizes, filenames []string, srcs [][]byte, man
                return
        }
 
-       // sort errlist in source order
-       sort.Slice(errlist, func(i, j int) bool {
-               // TODO(gri) This is not correct as scanner.Errors
-               // don't have a correctly set Offset. But we only
-               // care about sorting when multiple equal errors
-               // appear on the same line, which happens with some
-               // type checker errors.
-               // For now this works. Will remove need for sorting
-               // in a subsequent CL.
-               pi, _ := unpackError(fset, errlist[i])
-               pj, _ := unpackError(fset, errlist[j])
-               return pi.Offset < pj.Offset
-       })
-
        // collect expected errors
        errmap := make(map[string]map[int][]comment)
        for i, filename := range filenames {
@@ -206,6 +191,7 @@ func testFiles(t *testing.T, sizes Sizes, filenames []string, srcs [][]byte, man
        }
 
        // match against found errors
+       var indices []int // list indices of matching errors, reused for each error
        for _, err := range errlist {
                gotPos, gotMsg := unpackError(fset, err)
 
@@ -218,8 +204,8 @@ func testFiles(t *testing.T, sizes Sizes, filenames []string, srcs [][]byte, man
                        errList = filemap[line]
                }
 
-               // one of errors in errList should match the current error
-               index := -1 // errList index of matching message, if any
+               // At least one of the errors in errList should match the current error.
+               indices = indices[:0]
                for i, want := range errList {
                        pattern := strings.TrimSpace(want.text[len(" ERROR "):])
                        if n := len(pattern); n >= 2 && pattern[0] == '"' && pattern[n-1] == '"' {
@@ -231,20 +217,28 @@ func testFiles(t *testing.T, sizes Sizes, filenames []string, srcs [][]byte, man
                                continue
                        }
                        if rx.MatchString(gotMsg) {
-                               index = i
-                               break
+                               indices = append(indices, i)
                        }
                }
-               if index < 0 {
+               if len(indices) == 0 {
                        t.Errorf("%s: no error expected: %q", gotPos, gotMsg)
                        continue
                }
+               // len(indices) > 0
+
+               // If there are multiple matching errors, select the one with the closest column position.
+               index := -1 // index of matching error
+               var delta int
+               for _, i := range indices {
+                       if d := absDiff(gotPos.Column, errList[i].col); index < 0 || d < delta {
+                               index, delta = i, d
+                       }
+               }
 
-               // column position must be within expected colDelta
-               const colDelta = 0
-               want := errList[index]
-               if delta(gotPos.Column, want.col) > colDelta {
-                       t.Errorf("%s: got col = %d; want %d", gotPos, gotPos.Column, want.col)
+               // The closest column position must be within expected colDelta.
+               const colDelta = 0 // go/types errors are positioned correctly
+               if delta > colDelta {
+                       t.Errorf("%s: got col = %d; want %d", gotPos, gotPos.Column, errList[index].col)
                }
 
                // eliminate from errList