1# The gotypesalias GODEBUG setting was introduced with Go 1.22 and removed
2# with Go 1.27 but the GODEBUG behavior of the tool chain is independent of
3# the module version; only the tool version matters (go.dev/issue/76163).
4cp go.mod.20 go.mod
5
6# Go 1.20 must accept the removed GODEBUG gotypesalias with default value
7go build -n godebugok.go
8! stderr 'removed GODEBUG "gotypesalias" set to old value "0"'
9
10# This also applies to go vet
11go vet godebugok.go
12! stderr .
13
14# Go 1.20 must not accept the removed GODEBUG gotypesalias with old value
15! go build -n godebugold.go
16stderr 'removed GODEBUG "gotypesalias" set to old value "0"'
17
18! go vet godebugold.go
19stderr 'removed GODEBUG "gotypesalias" set to old value "0"'
20
21# If the GODEBUG setting is valid in the .mod file the build succeeds.
22cp go.mod.20.godebugok go.mod
23go build -n main.go
24! stderr 'removed GODEBUG "gotypesalias" set to old value "0"'
25
26# In this case, setting an invalid value in the .go file leads to build failure.
27! go build -n godebugold.go
28stderr 'removed GODEBUG "gotypesalias" set to old value "0"'
29
30# If the GODEBUG setting is invalid in the .mod file the build fails.
31cp go.mod.20.godebugold go.mod
32! go build -n main.go
33stderr 'removed GODEBUG "gotypesalias" set to old value "0"'
34
35# In this case, setting a valid value in the .go file does not remedy the failure.
36! go build -n godebugok.go
37stderr 'removed GODEBUG "gotypesalias" set to old value "0"'
38
39[short] skip
40
41# Using a removed GODEBUG with old value in the environment causes panic at startup.
42cp go.mod.20 go.mod
43env GODEBUG=gotypesalias=0
44! go run printgodebug.go
45stderr 'removed GODEBUG "gotypesalias" set to old value "0"'
46
47# Using a removed GODEBUG with default value in the environment is ok.
48env GODEBUG=gotypesalias=1
49go run printgodebug.go
50stdout gotypesalias=1
51
52# Setting a removed GODEBUG with old value in the environment during runtime is not guarded against.
53go run setgodebug.go
54stdout gotypesalias=0
55
56-- go.mod.20 --
57go 1.20
58module m
59
60-- go.mod.20.godebugok --
61go 1.20
62module m
63godebug gotypesalias=1
64
65-- go.mod.20.godebugold --
66go 1.20
67module m
68godebug gotypesalias=0
69
70-- main.go --
71package main
72func main() {}
73
74-- godebugok.go --
75//go:debug gotypesalias=1
76
77package main
78func main() {}
79
80-- godebugold.go --
81//go:debug gotypesalias=0
82
83package main
84func main() {}
85
86-- printgodebug.go --
87package main
88
89import "fmt"
90import "os"
91
92func main() {
93 fmt.Println(os.Getenv("GODEBUG"))
94}
95
96-- setgodebug.go --
97package main
98
99import "fmt"
100import "os"
101
102func main() {
103 os.Setenv("GODEBUG", "gotypesalias=0")
104 fmt.Println(os.Getenv("GODEBUG"))
105}
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