2 files changed, 106 insertions, 11 deletions

diff --git a/src/cmd/go/internal/work/exec.go b/src/cmd/go/internal/work/exec.go
index 55cd30bbd1..86738e233d 100644
--- a/src/cmd/go/internal/work/exec.go
+++ b/src/cmd/go/internal/work/exec.go
@@ -2583,27 +2583,47 @@ func (b *Builder) ccompile(a *Action, p *load.Package, outfile string, flags []s
 	// when -trimpath is enabled.
 	if b.gccSupportsFlag(compiler, "-fdebug-prefix-map=a=b") {
 		if cfg.BuildTrimpath || p.Goroot {
+			prefixMapFlag := "-fdebug-prefix-map"
+			if b.gccSupportsFlag(compiler, "-ffile-prefix-map=a=b") {
+				prefixMapFlag = "-ffile-prefix-map"
+			}
 			// Keep in sync with Action.trimpath.
-			// The trimmed paths are a little different, but we need to trim in the
+			// The trimmed paths are a little different, but we need to trim in mostly the
 			// same situations.
 			var from, toPath string
-			if m := p.Module; m != nil {
-				from = m.Dir
-				toPath = m.Path + "@" + m.Version
+			if m := p.Module; m == nil {
+				if p.Root == "" { // command-line-arguments in GOPATH mode, maybe?
+					from = p.Dir
+					toPath = p.ImportPath
+				} else if p.Goroot {
+					from = p.Root
+					toPath = "GOROOT"
+				} else {
+					from = p.Root
+					toPath = "GOPATH"
+				}
+			} else if m.Dir == "" {
+				// The module is in the vendor directory. Replace the entire vendor
+				// directory path, because the module's Dir is not filled in.
+				from = modload.VendorDir()
+				toPath = "vendor"
 			} else {
-				from = p.Dir
-				toPath = p.ImportPath
+				from = m.Dir
+				toPath = m.Path
+				if m.Version != "" {
+					m.Path += "@" + m.Version
+				}
 			}
-			// -fdebug-prefix-map requires an absolute "to" path (or it joins the path
-			// with the working directory). Pick something that makes sense for the
-			// target platform.
+			// -fdebug-prefix-map (or -ffile-prefix-map) requires an absolute "to"
+			// path (or it joins the path  with the working directory). Pick something
+			// that makes sense for the target platform.
 			var to string
 			if cfg.BuildContext.GOOS == "windows" {
 				to = filepath.Join(`\\_\_`, toPath)
 			} else {
 				to = filepath.Join("/_", toPath)
 			}
-			flags = append(slices.Clip(flags), "-fdebug-prefix-map="+from+"="+to)
+			flags = append(slices.Clip(flags), prefixMapFlag+"="+from+"="+to)
 		}
 	}
 
@@ -2786,7 +2806,11 @@ func (b *Builder) compilerCmd(compiler []string, incdir, workdir string) []strin
 			workdir = b.WorkDir
 		}
 		workdir = strings.TrimSuffix(workdir, string(filepath.Separator))
-		a = append(a, "-fdebug-prefix-map="+workdir+"=/tmp/go-build")
+		if b.gccSupportsFlag(compiler, "-ffile-prefix-map=a=b") {
+			a = append(a, "-ffile-prefix-map="+workdir+"=/tmp/go-build")
+		} else {
+			a = append(a, "-fdebug-prefix-map="+workdir+"=/tmp/go-build")
+		}
 	}
 
 	// Tell gcc not to include flags in object files, which defeats the
diff --git a/src/cmd/go/testdata/script/cgo_trimpath_macro.txt b/src/cmd/go/testdata/script/cgo_trimpath_macro.txt
new file mode 100644
index 0000000000..b5cc1167cb
--- /dev/null
+++ b/src/cmd/go/testdata/script/cgo_trimpath_macro.txt
@@ -0,0 +1,71 @@
+# This is a test that -trimpath trims the paths of every directory
+# of Cgo dependencies in the module, and trims file paths included
+# through the __FILE__ macro using --file-prefix-map.
+
+[!cgo] skip
+[short] skip 'links and runs binaries'
+
+# Test in main module.
+go run -trimpath -mod=vendor ./main
+stdout '(\\_\\_|/_)[\\/]m[\\/]c[\\/]bar.h'
+
+# Test in vendored module.
+go run -trimpath -mod=vendor v.com/main
+stdout '(\\_\\_|/_)[\\/]vendor[\\/]v.com[\\/]c[\\/]bar.h'
+
+# Test in GOPATH mode.
+env GO111MODULE=off
+go run -trimpath ./main
+stdout '(\\_\\_|/_)[\\/]GOPATH[\\/]src[\\/]c[\\/]bar.h'
+
+-- go.mod --
+module m
+
+require v.com v1.0.0
+-- go.sum --
+v.com v1.0.0 h1:xxx
+v.com v1.0.0/go.mod h1:xxx
+-- vendor/modules.txt --
+# v.com v1.0.0
+## explicit; go 1.20
+v.com/main
+-- vendor/v.com/main/main.go --
+package main
+
+// #cgo CFLAGS: -I../c
+// #include "stdio.h"
+// void printfile();
+import "C"
+
+func main() {
+    C.printfile()
+    C.fflush(C.stdout)
+}
+-- vendor/v.com/main/foo.c --
+#include "bar.h"
+-- vendor/v.com/c/bar.h --
+#include "stdio.h"
+
+void printfile() {
+    printf("%s\n", __FILE__);
+}
+-- main/main.go --
+package main
+
+// #cgo CFLAGS: -I../c
+// #include "stdio.h"
+// void printfile();
+import "C"
+
+func main() {
+    C.printfile()
+    C.fflush(C.stdout)
+}
+-- main/foo.c --
+#include "bar.h"
+-- c/bar.h --
+#include "stdio.h"
+
+void printfile() {
+    printf("%s\n", __FILE__);
+}
\ No newline at end of file