6 files changed, 35 insertions, 0 deletions
diff --git a/lib.c b/lib.c
index b018eb97..fb11738c 100644
--- a/lib.c
+++ b/lib.c
@@ -263,6 +263,7 @@ unsigned long fdump_ir;
 int fmem_report = 0;
 unsigned long long fmemcpy_max_count = 100000;
 unsigned long fpasses = ~0UL;
+int funsigned_char = 0;
 
 int preprocess_only;
 
@@ -878,6 +879,8 @@ static struct flag fflags[] = {
 	{ "tabstop=",		NULL,	handle_ftabstop },
 	{ "mem2reg",		NULL,	handle_fpasses,	PASS_MEM2REG },
 	{ "optim",		NULL,	handle_fpasses,	PASS_OPTIM },
+	{ "signed-char",	&funsigned_char, NULL,	OPT_INVERSE },
+	{ "unsigned-char",	&funsigned_char, NULL, },
 	{ },
 };
 
diff --git a/lib.h b/lib.h
index b0f34265..37d48672 100644
--- a/lib.h
+++ b/lib.h
@@ -171,6 +171,7 @@ extern int fmem_report;
 extern unsigned long fdump_ir;
 extern unsigned long long fmemcpy_max_count;
 extern unsigned long fpasses;
+extern int funsigned_char;
 
 extern int arch_m64;
 extern int arch_msize_long;
diff --git a/sparse.1 b/sparse.1
index 5b2bcd9c..efb01293 100644
--- a/sparse.1
+++ b/sparse.1
@@ -381,6 +381,11 @@ Set the distance between tab stops.  This helps sparse report correct
 column numbers in warnings or errors.  If the value is less than 1 or
 greater than 100, the option is ignored.  The default is 8.
 .
+.TP
+.B \-f[no-]unsigned-char, \-f[no-]signed-char
+Let plain 'char' be unsigned or signed.
+By default chars are signed.
+.
 .SH SEE ALSO
 .BR cgcc (1)
 .
diff --git a/symbol.c b/symbol.c
index 2f4afd51..773060ec 100644
--- a/symbol.c
+++ b/symbol.c
@@ -767,4 +767,10 @@ void init_ctype(void)
 		sym->ctype.base_type = ctype->base_type;
 		sym->ctype.modifiers = ctype->modifiers;
 	}
+
+	// and now some adjustments
+	if (funsigned_char) {
+		char_ctype.ctype.modifiers |= MOD_UNSIGNED;
+		char_ctype.ctype.modifiers &= ~MOD_SIGNED;
+	}
 }
diff --git a/validation/char-signed.c b/validation/char-signed.c
new file mode 100644
index 00000000..7f657dac
--- /dev/null
+++ b/validation/char-signed.c
@@ -0,0 +1,9 @@
+void foo(void)
+{
+	_Static_assert((char) -1 == -1, "plain char is not signed");
+}
+
+/*
+ * check-name: fsigned-char
+ * check-command: sparse -fsigned-char -Wno-decl $file
+ */
diff --git a/validation/char-unsigned.c b/validation/char-unsigned.c
new file mode 100644
index 00000000..19cadbda
--- /dev/null
+++ b/validation/char-unsigned.c
@@ -0,0 +1,11 @@
+#define	MASK ((1 << __CHAR_BIT__) - 1)
+
+void foo(void)
+{
+	_Static_assert((char) -1 == (-1 & MASK), "plain char is not unsigned");
+}
+
+/*
+ * check-name: fsigned-char
+ * check-command: sparse -funsigned-char -Wno-decl $file
+ */