From 19fdef46f960dd72fb5883514df25501db5b2d4e Mon Sep 17 00:00:00 2001
From: herman ten brugge <hermantenbrugge@home.nl>
Date: Fri, 15 Aug 2025 09:59:11 +0200
Subject: [PATCH] Allow mixing old/new function prototypes

This fixes another external testsuite failure
---
 tccgen.c                         | 23 +++++++++++++++++++----
 tests/tests2/133_old_func.c      |  8 ++++++++
 tests/tests2/133_old_func.expect |  1 +
 3 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/tccgen.c b/tccgen.c
index afb1567a..b6dbad2d 100644
--- a/tccgen.c
+++ b/tccgen.c
@@ -8517,7 +8517,7 @@ static int decl(int l)
 {
     int v, has_init, r, oldint;
     CType type, btype;
-    Sym *sym;
+    Sym *sym, *s;
     AttributeDef ad, adbase;
     ElfSym *esym;
 
@@ -8589,6 +8589,21 @@ static int decl(int l)
                 if (sym->f.func_type == FUNC_OLD && l == VT_CONST) {
                     func_vt = type;
                     decl(VT_CMP);
+
+		    /* Allow mixing old/new prototypes
+		     *   void func(float a);
+		     *   int main(void) { func(1.0); }
+		     *   void func(a) float a; { printf("%g\n", a); }
+		     */
+		    s = sym_find(v);
+		    if (type.ref->next && // skip old func(); definitions
+		        s && s->type.ref &&
+		        s->type.ref->f.func_type == FUNC_NEW) {
+		        sym->f.func_type = FUNC_NEW;
+		        if (!is_compatible_types(&s->type, &type))
+                            tcc_error("incompatible redefinition of '%s'",
+                                      get_tok_str(v, NULL));
+		    }
                 }
 
                 if ((type.t & (VT_EXTERN|VT_INLINE)) == (VT_EXTERN|VT_INLINE)) {
@@ -8646,6 +8661,9 @@ static int decl(int l)
                 while ((sym = sym->next) != NULL) {
                     if (!(sym->v & ~SYM_FIELD))
                         expect("identifier");
+		    if (type.ref->f.func_type == FUNC_OLD &&
+			sym->type.t == VT_FLOAT)
+			sym->type.t = VT_DOUBLE;
                     if (sym->type.t == VT_VOID)
                         sym->type = int_type;
                 }
@@ -8693,9 +8711,6 @@ static int decl(int l)
 		    if (sym->type.t != VT_VOID)
 		        tcc_error("redefinition of parameter '%s'",
 				  get_tok_str(v, NULL));
-		    if (func_vt.ref->f.func_type == FUNC_OLD &&
-			type.t == VT_FLOAT)
-			type.t = VT_DOUBLE;
 		    convert_parameter_type(&type);
 		    sym->type = type;
 		} else if (type.t & VT_TYPEDEF) {
diff --git a/tests/tests2/133_old_func.c b/tests/tests2/133_old_func.c
index 81b9b75a..cb702194 100644
--- a/tests/tests2/133_old_func.c
+++ b/tests/tests2/133_old_func.c
@@ -6,6 +6,8 @@ float x;
     return 2.0 * x;
 }
 
+void func(float a);
+
 int
 main(void)
 {
@@ -13,6 +15,7 @@ main(void)
 
     printf("%g %g\n", fx(2.0), fy(10.0));
     printf("%g %g\n", fx(2.0f), fy(10.0f));
+    func(1);
 }
 
 float fy(x)
@@ -21,3 +24,8 @@ float x;
     return 3.0 * x;
 }
 
+void func(a)
+float a;
+{
+    printf("%g\n", a);
+}
diff --git a/tests/tests2/133_old_func.expect b/tests/tests2/133_old_func.expect
index e93760b6..525ba06f 100644
--- a/tests/tests2/133_old_func.expect
+++ b/tests/tests2/133_old_func.expect
@@ -1,2 +1,3 @@
 4 30
 4 30
+1