Never add declarations without children to the AST

src/compiler/translator/IntermNode.cpp

@@ -1028,6 +1028,22 @@ TIntermTernary::TIntermTernary(TIntermTyped *cond,
         TIntermTernary::DetermineQualifier(cond, trueExpression, falseExpression));
 }
 
+TIntermLoop::TIntermLoop(TLoopType type,
+                         TIntermNode *init,
+                         TIntermTyped *cond,
+                         TIntermTyped *expr,
+                         TIntermBlock *body)
+    : mType(type), mInit(init), mCond(cond), mExpr(expr), mBody(body)
+{
+    // Declaration nodes with no children can appear if all the declarators just added constants to
+    // the symbol table instead of generating code. They're no-ops so don't add them to the tree.
+    if (mInit && mInit->getAsDeclarationNode() &&
+        mInit->getAsDeclarationNode()->getSequence()->empty())
+    {
+        mInit = nullptr;
+    }
+}
+
 // static
 TQualifier TIntermTernary::DetermineQualifier(TIntermTyped *cond,
                                               TIntermTyped *trueExpression,

src/compiler/translator/IntermNode.h

@@ -204,10 +204,7 @@ class TIntermLoop : public TIntermNode
                 TIntermNode *init,
                 TIntermTyped *cond,
                 TIntermTyped *expr,
-                TIntermBlock *body)
-        : mType(type), mInit(init), mCond(cond), mExpr(expr), mBody(body)
-    {
-    }
+                TIntermBlock *body);
 
     TIntermLoop *getAsLoopNode() override { return this; }
     void traverse(TIntermTraverser *it) override;

src/compiler/translator/Intermediate.cpp

@@ -80,7 +80,7 @@ TIntermBlock *TIntermediate::EnsureBlock(TIntermNode *node)
 
     blockNode = new TIntermBlock();
     blockNode->setLine(node->getLine());
-    blockNode->getSequence()->push_back(node);
+    blockNode->appendStatement(node);
     return blockNode;
 }
 

src/tests/gl_tests/GLSLTest.cpp

@@ -2770,6 +2770,37 @@ TEST_P(GLSLTest_ES3, NestedSamplingOperation)
     EXPECT_PIXEL_COLOR_EQ_VEC2(lr, simpleColors[3]);
 }
 
+// Tests that using a constant declaration as the only statement in a for loop without curly braces
+// doesn't crash.
+TEST_P(GLSLTest, ConstantStatementInForLoop)
+{
+    const std::string &vertexShader =
+        "void main()\n"
+        "{\n"
+        "    for (int i = 0; i < 10; ++i)\n"
+        "        const int b = 0;\n"
+        "}\n";
+
+    GLuint shader = CompileShader(GL_VERTEX_SHADER, vertexShader);
+    EXPECT_NE(0u, shader);
+    glDeleteShader(shader);
+}
+
+// Tests that using a constant declaration as a loop init expression doesn't crash. Note that this
+// test doesn't work on D3D9 due to looping limitations, so it is only run on ES3.
+TEST_P(GLSLTest_ES3, ConstantStatementAsLoopInit)
+{
+    const std::string &vertexShader =
+        "void main()\n"
+        "{\n"
+        "    for (const int i = 0; i < 0;) {}\n"
+        "}\n";
+
+    GLuint shader = CompileShader(GL_VERTEX_SHADER, vertexShader);
+    EXPECT_NE(0u, shader);
+    glDeleteShader(shader);
+}
+
 // Use this to select which configurations (e.g. which renderer, which GLES major version) these tests should be run against.
 ANGLE_INSTANTIATE_TEST(GLSLTest,
                        ES2_D3D9(),