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go/printer, gofmt: tuned table alignment for better results
The go/printer (and thus gofmt) uses a heuristic to determine whether to break alignment between elements of an expression list which is spread across multiple lines. The heuristic only kicked in if the entry sizes (character length) was above a certain threshold (20) and the ratio between the previous and current entry size was above a certain value (4). This heuristic worked reasonably most of the time, but also led to unfortunate breaks in many cases where a single entry was suddenly much smaller (or larger) then the previous one. The behavior of gofmt was sufficiently mysterious in some of these situations that many issues were filed against it. The simplest solution to address this problem is to remove the heuristic altogether and have a programmer introduce empty lines to force different alignments if it improves readability. The problem with that approach is that the places where it really matters, very long tables with many (hundreds, or more) entries, may be machine-generated and not "post-processed" by a human (e.g., unicode/utf8/tables.go). If a single one of those entries is overlong, the result would be that the alignment would force all comments or values in key:value pairs to be adjusted to that overlong value, making the table hard to read (e.g., that entry may not even be visible on screen and all other entries seem spaced out too wide). Instead, we opted for a slightly improved heuristic that behaves much better for "normal", human-written code. 1) The threshold is increased from 20 to 40. This disables the heuristic for many common cases yet even if the alignment is not "ideal", 40 is not that many characters per line with todays screens, making it very likely that the entire line remains "visible" in an editor. 2) Changed the heuristic to not simply look at the size ratio between current and previous line, but instead considering the geometric mean of the sizes of the previous (aligned) lines. This emphasizes the "overall picture" of the previous lines, rather than a single one (which might be an outlier). 3) Changed the ratio from 4 to 2.5. Now that we ignore sizes below 40, a ratio of 4 would mean that a new entry would have to be 4 times bigger (160) or smaller (10) before alignment would be broken. A ratio of 2.5 seems more sensible. Applied updated gofmt to all of src and misc. Also tested against several former issues that complained about this and verified that the output for the given examples is satisfactory (added respective test cases). Some of the files changed because they were not gofmt-ed in the first place. For #644. For #7335. For #10392. (and probably more related issues) Fixes #22852. Change-Id: I5e48b3d3b157a5cf2d649833b7297b33f43a6f6e
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32 files changed

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‎src/archive/tar/reader_test.go

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -378,9 +378,9 @@ func TestReader(t *testing.T) {
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"security.selinux": "unconfined_u:object_r:default_t:s0\x00",
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},
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PAXRecords: map[string]string{
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"mtime": "1386065770.449252304",
382-
"atime": "1389782991.41987522",
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"ctime": "1386065770.449252304",
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"mtime": "1386065770.449252304",
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"atime": "1389782991.41987522",
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"ctime": "1386065770.449252304",
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"SCHILY.xattr.security.selinux": "unconfined_u:object_r:default_t:s0\x00",
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},
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Format: FormatPAX,

‎src/cmd/doc/doc_test.go

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -115,7 +115,7 @@ var tests = []test{
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`var MultiLineVar = map\[struct{ ... }\]struct{ ... }{ ... }`, // Multi line variable.
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`func MultiLineFunc\(x interface{ ... }\) \(r struct{ ... }\)`, // Multi line function.
117117
`var LongLine = newLongLine\(("someArgument[1-4]", ){4}...\)`, // Long list of arguments.
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`type T1 = T2`, // Type alias
118+
`type T1 = T2`, // Type alias
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},
120120
[]string{
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`const internalConstant = 2`, // No internal constants.

‎src/cmd/go/testdata/src/dupload/p2/p2.go

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@@ -1,2 +1,3 @@
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package p2
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import _ "dupload/vendor/p"

‎src/cmd/go/testdata/src/exclude/x_linux.go

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@@ -1,4 +1,3 @@
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// +build windows
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package x
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‎src/cmd/go/testdata/src/my.pkg/main/main.go

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@@ -1,5 +1,7 @@
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package main
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import "my.pkg"
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func main() {
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println(pkg.Text)
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}

‎src/cmd/go/testdata/src/vetcycle/p.go

Lines changed: 4 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -1,11 +1,12 @@
11
package p
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3-
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type (
5-
_ interface{ m(B1) }
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_ interface{ m(B1) }
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A1 interface{ a(D1) }
76
B1 interface{ A1 }
8-
C1 interface{ B1 /* ERROR issue #18395 */ }
7+
C1 interface {
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B1 /* ERROR issue #18395 */
9+
}
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D1 interface{ C1 }
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)
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‎src/cmd/internal/obj/arm64/a.out.go

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -911,4 +911,4 @@ const (
911911
ARNG_H
912912
ARNG_S
913913
ARNG_D
914-
)
914+
)

‎src/cmd/internal/obj/arm64/asm7.go

Lines changed: 7 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -1668,13 +1668,13 @@ func cmp(a int, b int) bool {
16681668

16691669
case C_PSOREG_4:
16701670
switch b {
1671-
case C_ZOREG, C_PSOREG_8:
1671+
case C_ZOREG, C_PSOREG_8:
16721672
return true
16731673
}
16741674

16751675
case C_PSOREG:
16761676
switch b {
1677-
case C_ZOREG, C_PSOREG_8, C_PSOREG_4:
1677+
case C_ZOREG, C_PSOREG_8, C_PSOREG_4:
16781678
return true
16791679
}
16801680

@@ -4014,7 +4014,7 @@ func (c *ctxt7) asmout(p *obj.Prog, o *Optab, out []uint32) {
40144014
rt := int((p.To.Reg) & 31)
40154015
r := int((p.Reg) & 31)
40164016

4017-
o1 |= ((Q&1) << 30) | ((size&3) << 22) | (uint32(rf&31) << 16) | (uint32(r&31) << 5) | uint32(rt&31)
4017+
o1 |= ((Q & 1) << 30) | ((size & 3) << 22) | (uint32(rf&31) << 16) | (uint32(r&31) << 5) | uint32(rt&31)
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40194019
case 94: /* vext $imm4, Vm.<T>, Vn.<T>, Vd.<T> */
40204020
if p.From3Type() != obj.TYPE_REG {
@@ -4053,7 +4053,7 @@ func (c *ctxt7) asmout(p *obj.Prog, o *Optab, out []uint32) {
40534053
rt := int((p.To.Reg) & 31)
40544054
r := int((p.Reg) & 31)
40554055

4056-
o1 |= ((Q&1) << 30) | (uint32(r&31) << 16) | (uint32(index&15) << 11) | (uint32(rf&31) << 5) | uint32(rt&31)
4056+
o1 |= ((Q & 1) << 30) | (uint32(r&31) << 16) | (uint32(index&15) << 11) | (uint32(rf&31) << 5) | uint32(rt&31)
40574057

40584058
case 95: /* vushr $shift, Vn.<T>, Vd.<T> */
40594059
at := int((p.To.Reg >> 5) & 15)
@@ -4111,7 +4111,7 @@ func (c *ctxt7) asmout(p *obj.Prog, o *Optab, out []uint32) {
41114111
rt := int((p.To.Reg) & 31)
41124112
rf := int((p.Reg) & 31)
41134113

4114-
o1 |= ((Q&1) << 30) | (uint32(imm&127) << 16) | (uint32(rf&31) << 5) | uint32(rt&31)
4114+
o1 |= ((Q & 1) << 30) | (uint32(imm&127) << 16) | (uint32(rf&31) << 5) | uint32(rt&31)
41154115

41164116
case 96: /* vst1 Vt1.<T>[index], offset(Rn) */
41174117
af := int((p.From.Reg >> 5) & 15)
@@ -4183,7 +4183,7 @@ func (c *ctxt7) asmout(p *obj.Prog, o *Optab, out []uint32) {
41834183
o1 |= 26 << 23
41844184
}
41854185

4186-
o1 |= (uint32(Q&1) << 30) | (uint32(r&31) << 16) | ((opcode&7) << 13) | (uint32(S&1) << 12) | (uint32(size&3) << 10) | (uint32(rf&31) << 5) | uint32(rt&31)
4186+
o1 |= (uint32(Q&1) << 30) | (uint32(r&31) << 16) | ((opcode & 7) << 13) | (uint32(S&1) << 12) | (uint32(size&3) << 10) | (uint32(rf&31) << 5) | uint32(rt&31)
41874187

41884188
case 97: /* vld1 offset(Rn), vt.<T>[index] */
41894189
at := int((p.To.Reg >> 5) & 15)
@@ -4257,7 +4257,7 @@ func (c *ctxt7) asmout(p *obj.Prog, o *Optab, out []uint32) {
42574257
o1 |= 106 << 21
42584258
}
42594259

4260-
o1 |= (uint32(Q&1) << 30) | (uint32(r&31) << 16) | ((opcode&7) << 13) | (uint32(S&1) << 12) | (uint32(size&3) << 10) | (uint32(rf&31) << 5) | uint32(rt&31)
4260+
o1 |= (uint32(Q&1) << 30) | (uint32(r&31) << 16) | ((opcode & 7) << 13) | (uint32(S&1) << 12) | (uint32(size&3) << 10) | (uint32(rf&31) << 5) | uint32(rt&31)
42614261
}
42624262
out[0] = o1
42634263
out[1] = o2

‎src/cmd/pprof/pprof.go

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -75,8 +75,8 @@ func getProfile(source string, timeout time.Duration) (*profile.Profile, error)
7575
client := &http.Client{
7676
Transport: &http.Transport{
7777
ResponseHeaderTimeout: timeout + 5*time.Second,
78-
Proxy: http.ProxyFromEnvironment,
79-
TLSClientConfig: tlsConfig,
78+
Proxy: http.ProxyFromEnvironment,
79+
TLSClientConfig: tlsConfig,
8080
},
8181
}
8282
resp, err := client.Get(source)

‎src/cmd/vendor/github.com/google/pprof/internal/driver/fetch.go

Lines changed: 2 additions & 2 deletions
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