Do not insert duplicate SourceFile.

[cjgillot]

Based on #115507
Addresses #115507 (comment)

cc @Zoxc
r? @oli-obk

[rustbot]

Some changes occurred in src/tools/rustfmt

cc @rust-lang/rustfmt

Some changes occurred in compiler/rustc_codegen_cranelift

cc @bjorn3

Some changes occurred in src/tools/clippy

cc @rust-lang/clippy

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

[rust-log-analyzer]

The job x86_64-gnu-llvm-15 failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot)

GITHUB_ACTION=__run_7
GITHUB_ACTIONS=true
GITHUB_ACTION_REF=
GITHUB_ACTION_REPOSITORY=
GITHUB_ACTOR=cjgillot
GITHUB_API_URL=https://api.github.com
GITHUB_BASE_REF=master
GITHUB_ENV=/home/runner/work/_temp/_runner_file_commands/set_env_78d6141d-a424-4ffc-95f3-bd5a30c4e9c4
GITHUB_EVENT_NAME=pull_request
---
GITHUB_SERVER_URL=https://github.com
GITHUB_SHA=de6efa3a65bc77b16bbb07c4e08e6213e1e3a059
GITHUB_STATE=/home/runner/work/_temp/_runner_file_commands/save_state_78d6141d-a424-4ffc-95f3-bd5a30c4e9c4
GITHUB_STEP_SUMMARY=/home/runner/work/_temp/_runner_file_commands/step_summary_78d6141d-a424-4ffc-95f3-bd5a30c4e9c4
GITHUB_TRIGGERING_ACTOR=cjgillot
GITHUB_WORKFLOW_REF=rust-lang/rust/.github/workflows/ci.yml@refs/pull/115572/merge
GITHUB_WORKFLOW_SHA=de6efa3a65bc77b16bbb07c4e08e6213e1e3a059
GITHUB_WORKSPACE=/home/runner/work/rust/rust
GOROOT_1_18_X64=/opt/hostedtoolcache/go/1.18.10/x64
---
..............................F....

failures:

---- source_map::tests::t10 stdout ----
thread 'source_map::tests::t10' panicked at compiler/rustc_span/src/source_map/tests.rs:262:62:
error: test failed, to rerun pass `-p rustc_span --lib`
called `Option::unwrap()` on a `None` value


failures:
    source_map::tests::t10

[Zoxc]

The last commit looks good to me.

[bors]

☔ The latest upstream changes (presumably #117507) made this pull request unmergeable. Please resolve the merge conflicts.