cmd/cgo: don't force rewritten code onto a single line

Doing that appears to have been a mistake in CL 142883.

Fixes #67517

Change-Id: Iec6b897984a2e27ec596fc3c4c8129e9620afab1
Reviewed-on: https://go-review.googlesource.com/c/go/+/586676
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Russ Cox <rsc@golang.org>

src/cmd/cgo/gcc.go

@@ -924,7 +924,7 @@ func (p *Package) rewriteCall(f *File, call *Call) (string, bool) {
 			if rtype != name.FuncType.Result.Go {
 				needsUnsafe = true
 			}
-			sb.WriteString(gofmtLine(rtype))
+			sb.WriteString(gofmt(rtype))
 			result = true
 		}
 
@@ -960,7 +960,7 @@ func (p *Package) rewriteCall(f *File, call *Call) (string, bool) {
 				needsUnsafe = true
 			}
 			fmt.Fprintf(&sb, "var _cgo%d %s = %s; ", i,
-				gofmtLine(ptype), gofmtPos(arg, origArg.Pos()))
+				gofmt(ptype), gofmtPos(arg, origArg.Pos()))
 			continue
 		}
 
@@ -1682,7 +1682,7 @@ func (p *Package) rewriteName(f *File, r *Ref, addPosition bool) ast.Expr {
 // gofmtPos returns the gofmt-formatted string for an AST node,
 // with a comment setting the position before the node.
 func gofmtPos(n ast.Expr, pos token.Pos) string {
-	s := gofmtLine(n)
+	s := gofmt(n)
 	p := fset.Position(pos)
 	if p.Column == 0 {
 		return s

src/cmd/cgo/godefs.go

@@ -125,46 +125,3 @@ func gofmt(n interface{}) string {
 	}
 	return gofmtBuf.String()
 }
-
-// gofmtLineReplacer is used to put a gofmt-formatted string for an
-// AST expression onto a single line. The lexer normally inserts a
-// semicolon at each newline, so we can replace newline with semicolon.
-// However, we can't do that in cases where the lexer would not insert
-// a semicolon. We only have to worry about cases that can occur in an
-// expression passed through gofmt, which means composite literals and
-// (due to the printer possibly inserting newlines because of position
-// information) operators.
-var gofmtLineReplacer = strings.NewReplacer(
-	// Want to replace \n without ; after everything from
-	// https://golang.org/ref/spec#Operators_and_punctuation
-	// EXCEPT ++ -- ) ] }
-	"++\n", "++;",
-	"--\n", "--;",
-
-	"+\n", "+ ",
-	"-\n", "- ",
-	"*\n", "* ",
-	"/\n", "/ ",
-	"%\n", "% ",
-	"&\n", "& ",
-	"|\n", "| ",
-	"^\n", "^ ",
-	"<\n", "< ",
-	">\n", "> ",
-	"=\n", "= ",
-	"!\n", "! ", // not possible in gofmt today
-	"(\n", "(",
-	"[\n", "[", // not possible in gofmt today
-	"{\n", "{",
-	",\n", ",",
-	".\n", ". ",
-	":\n", ": ", // not possible in gofmt today
-
-	"\n", ";",
-)
-
-// gofmtLine returns the gofmt-formatted string for an AST node,
-// ensuring that it is on a single line.
-func gofmtLine(n interface{}) string {
-	return gofmtLineReplacer.Replace(gofmt(n))
-}

src/cmd/cgo/internal/test/test.go

@@ -933,6 +933,13 @@ typedef struct issue45451Undefined issue45451;
 extern void GoFunc49633(void*);
 void cfunc49633(void *context) { GoFunc49633(context); }
 
+// Issue 67517.
+typedef struct {
+	int a;
+	int* b;
+} issue67517struct;
+static void issue67517(issue67517struct* p) {}
+
 */
 import "C"
 
@@ -2321,3 +2328,24 @@ func test45451(t *testing.T) {
 func func52542[T ~[]C.int]() {}
 
 type type52542[T ~*C.float] struct{}
+
+// issue67517 is just a compilation test, there is no runtime test.
+func issue67517() {
+	C.issue67517(&C.issue67517struct{
+		a: 0,
+
+		b: nil,
+	})
+	C.issue67517(&C.issue67517struct{
+		a: 0,
+		// comment
+		b: nil,
+	})
+	C.issue67517(&C.issue67517struct{
+		a: 0 +
+			// comment
+			1,
+		// comment
+		b: nil,
+	})
+}

src/cmd/cgo/internal/testerrors/errors_test.go

@@ -126,6 +126,7 @@ func TestReportsTypeErrors(t *testing.T) {
 		"issue28721.go",
 		"issue33061.go",
 		"issue50710.go",
+		"issue67517.go",
 	} {
 		check(t, file)
 	}

src/cmd/cgo/internal/testerrors/testdata/issue67517.go

@@ -0,0 +1,19 @@
+// Copyright 2024 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+// typedef struct { int a; void* ptr; } S;
+// static void f(S* p) {}
+import "C"
+
+func main() {
+	C.f(&C.S{
+		a: 1+
+
+			(3 + ""), // ERROR HERE
+
+		ptr: nil,
+	})
+}