Disable using globals as l-values in global initializers

src/compiler/translator/ValidateGlobalInitializer.cpp

@@ -18,6 +18,8 @@ class ValidateGlobalInitializerTraverser : public TIntermTraverser
 
     void visitSymbol(TIntermSymbol *node) override;
     bool visitAggregate(Visit visit, TIntermAggregate *node) override;
+    bool visitBinary(Visit visit, TIntermBinary *node) override;
+    bool visitUnary(Visit visit, TIntermUnary *node) override;
 
     bool isValid() const { return mIsValid; }
     bool issueWarning() const { return mIssueWarning; }
@@ -70,6 +72,24 @@ bool ValidateGlobalInitializerTraverser::visitAggregate(Visit visit, TIntermAggr
     return true;
 }
 
+bool ValidateGlobalInitializerTraverser::visitBinary(Visit visit, TIntermBinary *node)
+{
+    if (node->isAssignment())
+    {
+        mIsValid = false;
+    }
+    return true;
+}
+
+bool ValidateGlobalInitializerTraverser::visitUnary(Visit visit, TIntermUnary *node)
+{
+    if (node->isAssignment())
+    {
+        mIsValid = false;
+    }
+    return true;
+}
+
 ValidateGlobalInitializerTraverser::ValidateGlobalInitializerTraverser(const TParseContext *context)
     : TIntermTraverser(true, false, false),
       mContext(context),

src/tests/compiler_tests/MalformedShader_test.cpp

@@ -525,6 +525,40 @@ TEST_F(MalformedShaderTest, AssignFunctionCallToGlobal)
     }
 }
 
+// Global variable initializers need to be constant expressions (ESSL 1.00 section 4.3)
+// Initializing with an assignment to another global should be an error.
+TEST_F(MalformedShaderTest, AssignAssignmentToGlobal)
+{
+    const std::string &shaderString =
+        "precision mediump float;\n"
+        "float c = 1.0;\n"
+        "float b = (c = 0.0);\n"
+        "void main() {\n"
+        "   gl_FragColor = vec4(b);\n"
+        "}\n";
+    if (compile(shaderString))
+    {
+        FAIL() << "Shader compilation succeeded, expecting failure " << mInfoLog;
+    }
+}
+
+// Global variable initializers need to be constant expressions (ESSL 1.00 section 4.3)
+// Initializing with incrementing another global should be an error.
+TEST_F(MalformedShaderTest, AssignIncrementToGlobal)
+{
+    const std::string &shaderString =
+        "precision mediump float;\n"
+        "float c = 1.0;\n"
+        "float b = (c++);\n"
+        "void main() {\n"
+        "   gl_FragColor = vec4(b);\n"
+        "}\n";
+    if (compile(shaderString))
+    {
+        FAIL() << "Shader compilation succeeded, expecting failure " << mInfoLog;
+    }
+}
+
 // Global variable initializers need to be constant expressions (ESSL 3.00 section 4.3)
 // Initializing with a non-constant global should be an error.
 TEST_F(MalformedShaderTest, AssignNonConstGlobalToGlobal)