[clang] [Clang] Don't retain template FoundDecl for conversion function calls (PR #138377)

[LLVM Continuous Integration via cfe-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-clang-aarch64-darwin` running on `doug-worker-4` while building `clang` at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/190/builds/19444

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 6 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'Clang-Unit :: ./AllClangUnitTests/9/48' FAILED ********************
Script(shard):
--
GTEST_OUTPUT=json:/Users/buildbot/buildbot-root/aarch64-darwin/build/tools/clang/unittests/./AllClangUnitTests-Clang-Unit-86994-9-48.json GTEST_SHUFFLE=0 GTEST_TOTAL_SHARDS=48 GTEST_SHARD_INDEX=9 /Users/buildbot/buildbot-root/aarch64-darwin/build/tools/clang/unittests/./AllClangUnitTests
--

Script:
--
/Users/buildbot/buildbot-root/aarch64-darwin/build/tools/clang/unittests/./AllClangUnitTests --gtest_filter=TimeProfilerTest.ConstantEvaluationC99
--
/Users/buildbot/buildbot-root/aarch64-darwin/llvm-project/clang/unittests/Support/TimeProfilerTest.cpp:349: Failure
Expected equality of these values:
  R"(
Frontend (test.c)
| ParseDeclarationOrFunctionDefinition (test.c:2:1)
| | isIntegerConstantExpr (<test.c:3:18>)
| | EvaluateKnownConstIntCheckOverflow (<test.c:3:18>)
| PerformPendingInstantiations
)"
    Which is: "\nFrontend (test.c)\n| ParseDeclarationOrFunctionDefinition (test.c:2:1)\n| | isIntegerConstantExpr (<test.c:3:18>)\n| | EvaluateKnownConstIntCheckOverflow (<test.c:3:18>)\n| PerformPendingInstantiations\n"
  buildTraceGraph(Json)
    Which is: "\nFrontend (test.c)\n| ParseDeclarationOrFunctionDefinition (test.c:2:1)\n| | isIntegerConstantExpr (<test.c:3:18>)\n| | EvaluateKnownConstIntCheckOverflow (<test.c:3:18>)\n| | PerformPendingInstantiations\n"
With diff:
@@ -4,3 +4,3 @@
 | | isIntegerConstantExpr (<test.c:3:18>)
 | | EvaluateKnownConstIntCheckOverflow (<test.c:3:18>)
-| PerformPendingInstantiations\n
+| | PerformPendingInstantiations\n



/Users/buildbot/buildbot-root/aarch64-darwin/llvm-project/clang/unittests/Support/TimeProfilerTest.cpp:349
Expected equality of these values:
  R"(
Frontend (test.c)
| ParseDeclarationOrFunctionDefinition (test.c:2:1)
| | isIntegerConstantExpr (<test.c:3:18>)
| | EvaluateKnownConstIntCheckOverflow (<test.c:3:18>)
| PerformPendingInstantiations
)"
    Which is: "\nFrontend (test.c)\n| ParseDeclarationOrFunctionDefinition (test.c:2:1)\n| | isIntegerConstantExpr (<test.c:3:18>)\n| | EvaluateKnownConstIntCheckOverflow (<test.c:3:18>)\n| PerformPendingInstantiations\n"
  buildTraceGraph(Json)
    Which is: "\nFrontend (test.c)\n| ParseDeclarationOrFunctionDefinition (test.c:2:1)\n| | isIntegerConstantExpr (<test.c:3:18>)\n| | EvaluateKnownConstIntCheckOverflow (<test.c:3:18>)\n| | PerformPendingInstantiations\n"
With diff:
@@ -4,3 +4,3 @@
 | | isIntegerConstantExpr (<test.c:3:18>)
 | | EvaluateKnownConstIntCheckOverflow (<test.c:3:18>)
-| PerformPendingInstantiations\n
+| | PerformPendingInstantiations\n

...

```

</details>

https://github.com/llvm/llvm-project/pull/138377