gopls/internal/lsp/source: forgive inliner failures in ill-typed code

The inliner algorithms make widespread assumptions that the input
is well-typed, and panic if the input doesn't compile.

Previously, gopls would propagate the panic in well-typed code,
but convert it to an error plus a bug.Report if the input had type
errors.  This change removes the bug.Report, since reporting such
failures via panic is the intended behavior.

(Recovering from another package's panic isn't ideal: what if it
fails using log.Fatal, or creates additional goroutines that
panic, or corrupts shared state? We happen to know that the
inline package does not, but that could change in future.)

Also, a test.

Fixes golang/go#64558

Change-Id: Id9e7ae1de66e6e50866cef4e907d5596e68cfa23
Reviewed-on: https://go-review.googlesource.com/c/tools/+/548736
Auto-Submit: Alan Donovan <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Robert Findley <[email protected]>

Author: adonovan

gopls/internal/lsp/source/inline.go

@@ -11,15 +11,13 @@ import (
 	"fmt"
 	"go/ast"
 	"go/types"
-	"runtime/debug"
 
 	"golang.org/x/tools/go/analysis"
 	"golang.org/x/tools/go/ast/astutil"
 	"golang.org/x/tools/go/types/typeutil"
 	"golang.org/x/tools/gopls/internal/file"
 	"golang.org/x/tools/gopls/internal/lsp/cache"
 	"golang.org/x/tools/gopls/internal/lsp/protocol"
-	"golang.org/x/tools/gopls/internal/util/bug"
 	"golang.org/x/tools/gopls/internal/util/safetoken"
 	"golang.org/x/tools/internal/diff"
 	"golang.org/x/tools/internal/event"
@@ -98,8 +96,7 @@ func inlineCall(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle, r
 	if bad(calleePkg) || bad(callerPkg) {
 		defer func() {
 			if x := recover(); x != nil {
-				err = bug.Errorf("inlining failed unexpectedly: %v\nstack: %v",
-					x, debug.Stack())
+				err = fmt.Errorf("inlining failed (%q), likely because inputs were ill-typed", x)
 			}
 		}()
 	}

gopls/internal/test/marker/testdata/codeaction/issue64558.txt

@@ -0,0 +1,14 @@
+Test of an inlining failure due to an ill-typed input program (#64558).
+
+-- go.mod --
+module testdata
+go 1.18
+
+-- a/a.go --
+package a
+
+func _() {
+	f(1, 2) //@ diag("2", re"too many arguments"), codeactionerr("f", ")", "refactor.inline", re`inlining failed \("args/params mismatch"\), likely because inputs were ill-typed`)
+}
+
+func f(int) {}