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Method call resolution fails with UnsolvedSymbolException if passed parameter is a list of two or more elements #3183

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mfarsikov opened this issue Mar 22, 2021 · 4 comments · May be fixed by #3194
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Method call resolution fails with UnsolvedSymbolException if passed parameter is a list of two or more elements #3183

mfarsikov opened this issue Mar 22, 2021 · 4 comments · May be fixed by #3194
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Bug report Symbol Solver

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@mfarsikov
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I'm using Javaparser 3.18.0.
The file to parse src/test/resources/MyClass.java:

import java.io.IOException;
import java.nio.file.Files;
import java.util.Arrays;

class MyClass {
    public void writeFile() throws IOException {
        Files.write(null, Arrays.asList("", ""));
    }
}

The parser (in Kotlin):

package my.package

import com.github.javaparser.ParserConfiguration
import com.github.javaparser.ast.body.ClassOrInterfaceDeclaration
import com.github.javaparser.ast.expr.MethodCallExpr
import com.github.javaparser.symbolsolver.JavaSymbolSolver
import com.github.javaparser.symbolsolver.resolution.typesolvers.ReflectionTypeSolver
import com.github.javaparser.utils.SourceRoot
import java.nio.file.Path

fun main() {
    val symbolSolver = JavaSymbolSolver(ReflectionTypeSolver())

    val sourceRoot = SourceRoot(
        Path.of("src/test/resources/"),
        ParserConfiguration().setSymbolResolver(symbolSolver)
    )

    val compilationUnit = sourceRoot.tryToParse()
        .single()
        .result.get()

    val methodCall = (compilationUnit.childNodes[3] as ClassOrInterfaceDeclaration)
        .methods.single().body.get()
        .childNodes.single()
        .childNodes.single() as MethodCallExpr

    methodCall.resolve()
}

In the attempt to resolve the method call it fails:

Exception in thread "main" UnsolvedSymbolException{context='null', name='We are unable to find the method declaration corresponding to Files.write(null, Arrays.asList("", ""))', cause='null'}
	at com.github.javaparser.symbolsolver.JavaSymbolSolver.resolveDeclaration(JavaSymbolSolver.java:167)
	at com.github.javaparser.ast.expr.MethodCallExpr.resolve(MethodCallExpr.java:313)
	at my.package.MainKt.main(Main.kt:28)
	at my.package.MainKt.main(Main.kt)

But if in parsed file list consists of a single element:
Files.write(null, Arrays.asList("", "")); -> Files.write(null, Arrays.asList(""));
it is solved correctly.
@maartenc maartenc mentioned this issue Mar 24, 2021
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@deadlocklogic
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I believe that this is a mix of an inference bug + maybe other bug (after a little analysis).
Actually consider this little related test:

List<MethodCallExpr> metCallExprs = cu.findAll(MethodCallExpr.class);
metCallExprs.forEach(metCallExpr -> {
    if (metCallExpr.getNameAsString().equals("asList")) {
        ResolvedType resolvedType = metCallExpr.calculateResolvedType();
        System.out.println(resolvedType.describe());
    }
});

The solved type is calculated as java.util.List<T> which is clearly wrong, it should be java.util.List<java.lang.String>.
Again, the generic part needs a lot of analysis/improvement.

@maartenc
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Yes I think the bug is in MethodCallExprContext, the method resolveMethodTypeParameters doesn't handle varargs properly I think. I tried to fix it in #3194 by reusing some other code that resolves type parameters as well, but now some other tests fail. I'll try to look into this

@deadlocklogic
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Yes as I remember correctly, the problem is exclusively when it tries to solve the usage of a MethodCallExprContext with a scope, otherwise the behavior is correct. So any calls to generic methods in outer classes will not be inferred correctly. I tried to create a patch but there is absolutely no documentation on any private methods called which is kinda frustrating and time consuming. So I have to wait a bit if someone more familiar on the subject before investigating further. Between many improvements needeed to the symbolsolver, documentation comes in first places.

@jlerbsc
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jlerbsc commented Dec 6, 2022

This issue is corrected in the current snapshot release.

@jlerbsc jlerbsc closed this as completed Dec 6, 2022
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Bug report Symbol Solver
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@MysterAitch @maartenc @jlerbsc @mfarsikov @deadlocklogic