Fix CI

Author: kevin-valerio

README.md

@@ -121,6 +121,7 @@ GOROOT=/path/to/go-panikint /path/to/go-panikint/bin/go test -v .
 CI notes:
 - Pull requests run workflow linting (actionlint + zizmor), `go vet`, and type checking (`go test -run=^$`) in `tests/` using the built toolchain.
 - Pushes to `master` run the build + tests (both truncation disabled/enabled).
+- The compiler may generate many identical panic message strings; string symbol emission is serialized to avoid rare `go:string."..." redeclared` build failures.
 
 Note: the upstream Go distribution tests in `$GOROOT/test` intentionally rely on integer wrap-around.
 The go-panikint unit tests live in `$GOROOT/tests` (plural) and should run with overflow checks enabled.

src/cmd/compile/internal/staticdata/data.go

@@ -64,6 +64,8 @@ const (
 	stringSymPattern = ".gostring.%d.%s"
 )
 
+var stringSymMu sync.Mutex
+
 // shortHashString converts the hash to a string for use with stringSymPattern.
 // We cut it to 16 bytes and then base64-encode to make it even smaller.
 func shortHashString(hash []byte) string {
@@ -88,11 +90,13 @@ func StringSym(pos src.XPos, s string) (data *obj.LSym) {
 	}
 
 	symdata := base.Ctxt.Lookup(stringSymPrefix + symname)
+	stringSymMu.Lock()
 	if !symdata.OnList() {
 		off := dstringdata(symdata, 0, s, pos, "string")
 		objw.Global(symdata, int32(off), obj.DUPOK|obj.RODATA|obj.LOCAL)
 		symdata.Set(obj.AttrContentAddressable, true)
 	}
+	stringSymMu.Unlock()
 
 	return symdata
 }