From a5e9812f12ff738d1caca08143132f49c8027115 Mon Sep 17 00:00:00 2001
From: Matthew Fernandez <matthew.fernandez@gmail.com>
Date: Sat, 27 Nov 2021 18:39:31 -0800
Subject: [PATCH] fix misuse of 'gvjobs_output_langname'

Many callers of `gvjobs_output_langname` were written as if this function
returns `NO_SUPPORT` when given an unsupported language. But this is incorrect.
It returns `FALSE`.
---
 CHANGELOG.md                    | 4 ++++
 lib/gvc/gvc.c                   | 8 ++++----
 tclpkg/tcldot/tcldot-graphcmd.c | 7 +++----
 3 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5ead58b49..7f24d3134 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased (2.50.1)]
 
+### Fixed
+
+- fix detection of unavailable output format
+
 ## [2.50.0] – 2021-12-04
 
 ### Added
diff --git a/lib/gvc/gvc.c b/lib/gvc/gvc.c
index e9810f135..c7386dea3 100644
--- a/lib/gvc/gvc.c
+++ b/lib/gvc/gvc.c
@@ -89,7 +89,7 @@ int gvRender(GVC_t *gvc, graph_t *g, const char *format, FILE *out)
     /* create a job for the required format */
     rc = gvjobs_output_langname(gvc, format);
     job = gvc->job;
-    if (rc == NO_SUPPORT) {
+    if (!rc) {
         agerr (AGERR, "Format: \"%s\" not recognized. Use one of:%s\n",
                 format, gvplugin_list(gvc, API_device, format));
         return -1;
@@ -121,7 +121,7 @@ int gvRenderFilename(GVC_t *gvc, graph_t *g, const char *format, const char *fil
     /* create a job for the required format */
     rc = gvjobs_output_langname(gvc, format);
     job = gvc->job;
-    if (rc == NO_SUPPORT) {
+    if (!rc) {
 	agerr(AGERR, "Format: \"%s\" not recognized. Use one of:%s\n",
                 format, gvplugin_list(gvc, API_device, format));
 	return -1;
@@ -152,7 +152,7 @@ int gvRenderContext(GVC_t *gvc, graph_t *g, const char *format, void *context)
     /* create a job for the required format */
     rc = gvjobs_output_langname(gvc, format);
     job = gvc->job;
-    if (rc == NO_SUPPORT) {
+    if (!rc) {
 		agerr(AGERR, "Format: \"%s\" not recognized. Use one of:%s\n",
 			  format, gvplugin_list(gvc, API_device, format));
 		return -1;
@@ -186,7 +186,7 @@ int gvRenderData(GVC_t *gvc, graph_t *g, const char *format, char **result, unsi
     /* create a job for the required format */
     rc = gvjobs_output_langname(gvc, format);
     job = gvc->job;
-    if (rc == NO_SUPPORT) {
+    if (!rc) {
 	agerr(AGERR, "Format: \"%s\" not recognized. Use one of:%s\n",
                 format, gvplugin_list(gvc, API_device, format));
 	return -1;
diff --git a/tclpkg/tcldot/tcldot-graphcmd.c b/tclpkg/tcldot/tcldot-graphcmd.c
index aeeb373be..42a6cfb7e 100644
--- a/tclpkg/tcldot/tcldot-graphcmd.c
+++ b/tclpkg/tcldot/tcldot-graphcmd.c
@@ -26,7 +26,7 @@ int graphcmd(ClientData clientData, Tcl_Interp * interp,
     ictx_t *ictx = gctx->ictx;
     Agsym_t *a;
     char c, buf[256], **argv2;
-    int i, j, argc2, rc;
+    int i, j, argc2;
     size_t length;
     GVC_t *gvc = ictx->gvc;
     GVJ_t *job = gvc->job;
@@ -328,8 +328,7 @@ int graphcmd(ClientData clientData, Tcl_Interp * interp,
 	} else {
 	    canvas = argv[2];
 	}
-        rc = gvjobs_output_langname(gvc, "tk");
-	if (rc == NO_SUPPORT) {
+	if (!gvjobs_output_langname(gvc, "tk")) {
 	    Tcl_AppendResult(interp, " Format: \"tk\" not recognized.\n", NULL);
 	    return TCL_ERROR;
 	}
@@ -453,7 +452,7 @@ int graphcmd(ClientData clientData, Tcl_Interp * interp,
 	} else {
 	    i = gvjobs_output_langname(gvc, argv[3]);
 	}
-	if (i == NO_SUPPORT) {
+	if (!i) {
 	    const char *s = gvplugin_list(gvc, API_render, argv[3]);
 	    Tcl_AppendResult(interp, "bad langname: \"", argv[3], "\". Use one of:", s, NULL);
 	    return TCL_ERROR;
-- 
2.40.0