cmd/compile: only check implicit dots for method call enabled by a type bound

Fixes #53419

Change-Id: Ibad64f5c4af2112deeb0a9ecc9c589b17594bd05
Reviewed-on: https://go-review.googlesource.com/c/go/+/414836
Reviewed-by: Matthew Dempsky <[email protected]>
Reviewed-by: David Chase <[email protected]>
Reviewed-by: Keith Randall <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
Run-TryBot: Cuong Manh Le <[email protected]>

Author: cuonglm

src/cmd/compile/internal/noder/stencil.go

@@ -1654,12 +1654,14 @@ func (g *genInst) getDictionarySym(gf *ir.Name, targs []*types.Type, isMeth bool
 				se := call.X.(*ir.SelectorExpr)
 				if se.X.Type().IsShape() {
 					// This is a method call enabled by a type bound.
-
-					// We need this extra check for method expressions,
-					// which don't add in the implicit XDOTs.
-					tmpse := ir.NewSelectorExpr(src.NoXPos, ir.OXDOT, se.X, se.Sel)
-					tmpse = typecheck.AddImplicitDots(tmpse)
-					tparam := tmpse.X.Type()
+					tparam := se.X.Type()
+					if call.X.Op() == ir.ODOTMETH {
+						// We need this extra check for method expressions,
+						// which don't add in the implicit XDOTs.
+						tmpse := ir.NewSelectorExpr(src.NoXPos, ir.OXDOT, se.X, se.Sel)
+						tmpse = typecheck.AddImplicitDots(tmpse)
+						tparam = tmpse.X.Type()
+					}
 					if !tparam.IsShape() {
 						// The method expression is not
 						// really on a typeparam.

test/run.go

@@ -1966,7 +1966,6 @@ var types2Failures32Bit = setOf(
 var go118Failures = setOf(
 	"typeparam/nested.go",     // 1.18 compiler doesn't support function-local types with generics
 	"typeparam/issue51521.go", // 1.18 compiler produces bad panic message and link error
-	"typeparam/issue53419.go", // 1.18 compiler mishandles generic selector resolution
 )
 
 // In all of these cases, the 1.17 compiler reports reasonable errors, but either the