[AA-FIR] Add support for constant evaluation of string templates.

Support FirStringConcatenationCall in FirCompileTimeConstantEvaluator.
This allows string templates ("foo${bar}") to be evaluated as constants,
assuming the interpolated expressions are themselves constant.

In addition, fixes some handling bugs with KtConstantEvaluationMode,
where some expressions that are not valid in a `const val` declaration
were being supported for `CONSTANT_EXPRESSION_EVALUATION`, including
non-static final Java fields in FIR, and composite expressions of
non-const properties in FE1.0.

analysis/analysis-api-fir/src/org/jetbrains/kotlin/analysis/api/fir/evaluate/FirCompileTimeConstantEvaluator.kt

@@ -15,6 +15,7 @@ import org.jetbrains.kotlin.fir.declarations.FirResolvePhase
 import org.jetbrains.kotlin.fir.declarations.FirSimpleFunction
 import org.jetbrains.kotlin.fir.declarations.utils.isConst
 import org.jetbrains.kotlin.fir.declarations.utils.isFinal
+import org.jetbrains.kotlin.fir.declarations.utils.isStatic
 import org.jetbrains.kotlin.fir.expressions.*
 import org.jetbrains.kotlin.fir.expressions.builder.buildConstExpression
 import org.jetbrains.kotlin.fir.psi
@@ -66,6 +67,9 @@ internal object FirCompileTimeConstantEvaluator {
             is FirFunctionCall -> {
                 evaluateFunctionCall(fir, mode)
             }
+            is FirStringConcatenationCall -> {
+                evaluateStringConcatenationCall(fir, mode)
+            }
             is FirNamedReference -> {
                 fir.toResolvedPropertySymbol()?.toConstExpression(mode)
             }
@@ -93,7 +97,7 @@ internal object FirCompileTimeConstantEvaluator {
         mode: KtConstantEvaluationMode,
     ): FirConstExpression<*>? {
         return when {
-            mode == KtConstantEvaluationMode.CONSTANT_EXPRESSION_EVALUATION && !isFinal -> null
+            mode == KtConstantEvaluationMode.CONSTANT_EXPRESSION_EVALUATION && !(isStatic && isFinal) -> null
             isVal && hasInitializer -> {
                 evaluate(fir.initializer, mode)
             }
@@ -152,6 +156,20 @@ internal object FirCompileTimeConstantEvaluator {
         )
     }
 
+    private fun evaluateStringConcatenationCall(
+        stringConcatenationCall: FirStringConcatenationCall,
+        mode: KtConstantEvaluationMode,
+    ): FirConstExpression<String>? {
+        val concatenated = buildString {
+            for (arg in stringConcatenationCall.arguments) {
+                val evaluated = evaluate(arg, mode) ?: return null
+                append(evaluated.value.toString())
+            }
+        }
+
+        return ConstantValueKind.String.toConstExpression(stringConcatenationCall.source, concatenated)
+    }
+
     private fun evaluateFunctionCall(
         functionCall: FirFunctionCall,
         mode: KtConstantEvaluationMode,

analysis/analysis-api-fir/tests-gen/org/jetbrains/kotlin/analysis/api/fir/test/cases/generated/cases/components/compileTimeConstantProvider/FirIdeDependentAnalysisSourceModuleCompileTimeConstantEvaluatorTestGenerated.java

@@ -232,6 +232,18 @@ public class FirIdeDependentAnalysisSourceModuleCompileTimeConstantEvaluatorTest
         runTest("analysis/analysis-api/testData/components/compileTimeConstantProvider/evaluate/string_plusTwice.kt");
     }
 
+    @Test
+    @TestMetadata("string_templateConst.kt")
+    public void testString_templateConst() throws Exception {
+        runTest("analysis/analysis-api/testData/components/compileTimeConstantProvider/evaluate/string_templateConst.kt");
+    }
+
+    @Test
+    @TestMetadata("string_templateNonConst.kt")
+    public void testString_templateNonConst() throws Exception {
+        runTest("analysis/analysis-api/testData/components/compileTimeConstantProvider/evaluate/string_templateNonConst.kt");
+    }
+
     @Test
     @TestMetadata("string_toString.kt")
     public void testString_toString() throws Exception {

analysis/analysis-api-fir/tests-gen/org/jetbrains/kotlin/analysis/api/fir/test/cases/generated/cases/components/compileTimeConstantProvider/FirIdeNormalAnalysisSourceModuleCompileTimeConstantEvaluatorTestGenerated.java

@@ -232,6 +232,18 @@ public class FirIdeNormalAnalysisSourceModuleCompileTimeConstantEvaluatorTestGen
         runTest("analysis/analysis-api/testData/components/compileTimeConstantProvider/evaluate/string_plusTwice.kt");
     }
 
+    @Test
+    @TestMetadata("string_templateConst.kt")
+    public void testString_templateConst() throws Exception {
+        runTest("analysis/analysis-api/testData/components/compileTimeConstantProvider/evaluate/string_templateConst.kt");
+    }
+
+    @Test
+    @TestMetadata("string_templateNonConst.kt")
+    public void testString_templateNonConst() throws Exception {
+        runTest("analysis/analysis-api/testData/components/compileTimeConstantProvider/evaluate/string_templateNonConst.kt");
+    }
+
     @Test
     @TestMetadata("string_toString.kt")
     public void testString_toString() throws Exception {