fix(extgen): emit parser warnings to stderr instead of stdout (#2374)

Author: alexandre-daubois

internal/extgen/classparser.go

@@ -87,7 +87,7 @@ func (cp *classParser) parse(filename string) (classes []phpClass, err error) {
 			}
 
 			if err := validator.validateClass(class); err != nil {
-				fmt.Printf("Warning: Invalid class '%s': %v\n", class.Name, err)
+				fmt.Fprintf(os.Stderr, "Warning: Invalid class '%s': %v\n", class.Name, err)
 				continue
 			}
 
@@ -229,7 +229,7 @@ func (cp *classParser) parseMethods(filename string) (methods []phpClassMethod,
 
 			method, err := cp.parseMethodSignature(className, signature)
 			if err != nil {
-				fmt.Printf("Warning: Error parsing method signature %q: %v\n", signature, err)
+				fmt.Fprintf(os.Stderr, "Warning: Error parsing method signature %q: %v\n", signature, err)
 
 				continue
 			}
@@ -244,7 +244,7 @@ func (cp *classParser) parseMethods(filename string) (methods []phpClassMethod,
 			}
 
 			if err := validator.validateTypes(phpFunc); err != nil {
-				fmt.Printf("Warning: Method \"%s::%s\" uses unsupported types: %v\n", className, method.Name, err)
+				fmt.Fprintf(os.Stderr, "Warning: Method \"%s::%s\" uses unsupported types: %v\n", className, method.Name, err)
 
 				continue
 			}
@@ -272,7 +272,7 @@ func (cp *classParser) parseMethods(filename string) (methods []phpClassMethod,
 			}
 
 			if err := validator.validateGoFunctionSignatureWithOptions(phpFunc, true); err != nil {
-				fmt.Printf("Warning: Go method signature mismatch for '%s::%s': %v\n", currentMethod.ClassName, currentMethod.Name, err)
+				fmt.Fprintf(os.Stderr, "Warning: Go method signature mismatch for '%s::%s': %v\n", currentMethod.ClassName, currentMethod.Name, err)
 				currentMethod = nil
 				continue
 			}

internal/extgen/funcparser.go

@@ -38,19 +38,19 @@ func (fp *FuncParser) parse(filename string) (functions []phpFunction, err error
 			signature := strings.TrimSpace(matches[1])
 			phpFunc, err := fp.parseSignature(signature)
 			if err != nil {
-				fmt.Printf("Warning: Error parsing signature '%s': %v\n", signature, err)
+				fmt.Fprintf(os.Stderr, "Warning: Error parsing signature '%s': %v\n", signature, err)
 
 				continue
 			}
 
 			if err := validator.validateFunction(*phpFunc); err != nil {
-				fmt.Printf("Warning: Invalid function '%s': %v\n", phpFunc.Name, err)
+				fmt.Fprintf(os.Stderr, "Warning: Invalid function '%s': %v\n", phpFunc.Name, err)
 
 				continue
 			}
 
 			if err := validator.validateTypes(*phpFunc); err != nil {
-				fmt.Printf("Warning: Function '%s' uses unsupported types: %v\n", phpFunc.Name, err)
+				fmt.Fprintf(os.Stderr, "Warning: Function '%s' uses unsupported types: %v\n", phpFunc.Name, err)
 
 				continue
 			}
@@ -68,7 +68,7 @@ func (fp *FuncParser) parse(filename string) (functions []phpFunction, err error
 			currentPHPFunc.GoFunction = goFunc
 
 			if err := validator.validateGoFunctionSignatureWithOptions(*currentPHPFunc, false); err != nil {
-				fmt.Printf("Warning: Go function signature mismatch for %q: %v\n", currentPHPFunc.Name, err)
+				fmt.Fprintf(os.Stderr, "Warning: Go function signature mismatch for %q: %v\n", currentPHPFunc.Name, err)
 				currentPHPFunc = nil
 
 				continue