test: add extra highlighting for the backtrace

Pass through the function name where the condition failed so we can
highlight that line in the backtrace.

Part-of: <https://gitlab.freedesktop.org/libinput/libinput/-/merge_requests/1159>

src/util-backtrace.h

@@ -43,12 +43,16 @@
  * If use_colors is true, highlight_before may specify
  * a substring for a line before which the backtrace is
  * colored.
+ *
+ * If use_colors is true, highlight_extra may specify
+ * a substring for a line that has extra highlighting.
  */
 static inline void
 backtrace_print(FILE *fp,
 		bool use_colors,
 		const char *highlight_after,
-		const char *highlight_before)
+		const char *highlight_before,
+		const char *highlight_extra)
 {
 #if HAVE_GSTACK
 	pid_t parent, child;
@@ -98,8 +102,15 @@ backtrace_print(FILE *fp,
 		while (line && *line) {
 			if (highlight && highlight_before && strstr(*line, highlight_before))
 				highlight = false;
+
+			const char *hlcolor = highlight ? ANSI_BRIGHT_CYAN : "";
+
+			if (highlight && highlight_extra &&
+			    strstr(*line, highlight_extra))
+				hlcolor = ANSI_BRIGHT_MAGENTA;
+
 			fprintf(fp, "%s%s%s\n",
-				highlight ? ANSI_BRIGHT_CYAN : "",
+				hlcolor,
 				*line,
 				highlight ? ANSI_NORMAL : "");
 			if (!highlight && highlight_after && strstr(*line, highlight_after))

test/litest-runner.c

@@ -283,7 +283,7 @@ sighandler_forked_child(int signal)
          * the backtrace anyway -  we only need to backtrace the other signals
          */
         if (signal != SIGABRT)
-		litest_backtrace();
+		litest_backtrace(NULL);
 
 	raise(signal);
 }

test/litest.c

@@ -168,15 +168,22 @@ _litest_checkpoint(const char *func,
 }
 
 void
-litest_backtrace(void)
+litest_backtrace(const char *func)
 {
 #ifndef LITEST_DISABLE_BACKTRACE_LOGGING
 	if (RUNNING_ON_VALGRIND) {
 		fprintf(stderr, "Using valgrind, omitting backtrace\n");
 		return;
 	}
+	char buf[256];
 
-	backtrace_print(stderr, use_colors, "in litest_backtrace", "in litest_runner_test_run");
+	snprintf(buf, sizeof(buf), "in %s", func);
+
+	backtrace_print(stderr,
+			use_colors,
+			"in litest_backtrace",
+			"in litest_runner_test_run",
+			func ? buf : NULL);
 #endif
 }
 
@@ -202,7 +209,7 @@ litest_fail_condition(const char *file,
 	}
 
 	litest_log("in %s() (%s:%d)\n", func, file, line);
-	litest_backtrace();
+	litest_backtrace(func);
 	litest_runner_abort();
 }
 
@@ -220,7 +227,7 @@ litest_fail_comparison_int(const char *file,
 	litest_log("FAILED COMPARISON: %s %s %s\n", astr, operator, bstr);
 	litest_log("Resolved to: %d %s %d\n", a, operator, b);
 	litest_log("in %s() (%s:%d)\n", func, file, line);
-	litest_backtrace();
+	litest_backtrace(func);
 	litest_runner_abort();
 }
 
@@ -238,7 +245,7 @@ litest_fail_comparison_double(const char *file,
 	litest_log("FAILED COMPARISON: %s %s %s\n", astr, operator, bstr);
 	litest_log("Resolved to: %.3f %s %.3f\n", a, operator, b);
 	litest_log("in %s() (%s:%d)\n", func, file, line);
-	litest_backtrace();
+	litest_backtrace(func);
 	litest_runner_abort();
 }
 
@@ -251,7 +258,7 @@ litest_fail_comparison_ptr(const char *file,
 {
 	litest_log("FAILED COMPARISON: %s\n", comparison);
 	litest_log("in %s() (%s:%d)\n", func, file, line);
-	litest_backtrace();
+	litest_backtrace(func);
 	litest_runner_abort();
 }
 
@@ -268,7 +275,7 @@ litest_fail_comparison_str(const char *file,
 	litest_log("FAILED COMPARISON: %s %s %s\n", astr, operator, bstr);
 	litest_log("Resolved to: %s %s %s\n", astr, operator, bstr);
 	litest_log("in %s() (%s:%d)\n", func, file, line);
-	litest_backtrace();
+	litest_backtrace(func);
 	litest_runner_abort();
 }
 
@@ -3708,7 +3715,7 @@ _litest_assert_event_type_is_one_of(struct libinput_event *event, ...)
 	fprintf(stderr, "\n");
 
 	litest_print_event(event, "Wrong event is:");
-	litest_backtrace();
+	litest_backtrace(__func__);
 	litest_runner_abort();
 }
 
@@ -3748,7 +3755,7 @@ _litest_assert_event_type_not_one_of(struct libinput_event *event, ...)
 		libinput_event_get_type(event));
 
 	litest_print_event(event,"\nWrong event is: ");
-	litest_backtrace();
+	litest_backtrace(__func__);
 	litest_runner_abort();
 }
 

test/litest.h

@@ -359,7 +359,7 @@ litest_fail_comparison_str(const char *file,
 #define litest_assert_double_ge(a_, b_)\
 	litest_assert_double_ge_epsilon((a_), (b_),LITEST_DEFAULT_EPSILON)
 
-void litest_backtrace(void);
+void litest_backtrace(const char *func);
 
 enum litest_device_type {
 	LITEST_NO_DEVICE = -1,