cxgo: Fix side effects for assign expr. Fixes #77.

Author: dennwc

c_expr.go

@@ -1193,7 +1193,7 @@ func (e *CAssignExpr) AsExpr() GoExpr {
 		define(pg, x.AsExpr()),
 	)
 	stmts = append(stmts,
-		e.Stmt.g.NewCAssignStmtP(e.Stmt.g.cDeref(x), e.Stmt.Op, y).AsStmt()...,
+		e.Stmt.g.NewCAssignStmtP(e.Stmt.g.cDeref(PtrIdent{p}), e.Stmt.Op, y).AsStmt()...,
 	)
 	stmts = append(stmts,
 		returnStmt(deref(pg)),

compile_test.go

@@ -105,7 +105,7 @@ func goProject(t testing.TB, out, cxgo string) {
 	require.NoError(t, err)
 
 	gomod := fmt.Sprintf(`module main
-go 1.18
+go 1.19
 require (
 	github.com/gotranspile/cxgo v0.0.0-local
 )

parse_test.go

@@ -688,6 +688,39 @@ func foo() {
 		return a
 	}()
 }
+`,
+	},
+	{
+		name: "assign expr side effect",
+		src: `
+
+int global = 0;
+int* calc(int v) {
+	global += v;
+	return &global;
+}
+
+void foo() {
+	int a;
+	a = *calc(1) += *calc(2);
+}
+`,
+		exp: `
+var global int32 = 0
+
+func calc(v int32) *int32 {
+	global += v
+	return &global
+}
+func foo() {
+	var a int32
+	_ = a
+	a = func() int32 {
+		p := calc(1)
+		*p += *calc(2)
+		return *p
+	}()
+}
 `,
 	},
 	{

run_test.go

@@ -0,0 +1,51 @@
+package cxgo
+
+import "testing"
+
+var casesRun = []struct {
+	name string
+	src  string
+}{
+	{
+		name: "issue 77",
+		src: `
+#include <stdio.h>
+
+int globe = 35;
+
+
+int* fn1(int strd) {
+	static int result = 0; 
+    result = globe;
+    if (strd > 2) {
+        result += 4;
+    }
+    result += strd;
+    return &result; 
+}
+
+int main() {
+    char q_q = 34;
+    int p_p = 110; 
+    p_p += q_q ^ p_p || globe; 
+    q_q = globe ^ p_p ^ 25;
+    printf("%d\n", *fn1(q_q));
+    printf("%d\n", *fn1(p_p));
+	int t1 = *fn1(q_q);
+	int t2 = *fn1(p_p);
+    int final=t1 += t2; 
+    printf("Result: %d\n", final ); 
+    return 0;
+}
+`,
+	},
+}
+
+func TestRunTranslated(t *testing.T) {
+	for _, c := range casesRun {
+		c := c
+		t.Run(c.name, func(t *testing.T) {
+			testTranspileOut(t, c.src)
+		})
+	}
+}