Merge pull request #1192 from zama-ai/fix/ci_fontconfig

fix fontconfig missing in ci

.github/workflows/concrete_optimizer.yml

@@ -42,6 +42,11 @@ jobs:
           cargo --version
           cd compilers/concrete-optimizer
           cargo fmt --check
+      - name: Fix fontconfig on ubuntu
+        if: ${{ matrix.runson == 'ubuntu-latest' }}
+        run: |
+          sudo apt update
+          sudo apt -y install libfontconfig1-dev
       - name: Build
         run: |
           cd compilers/concrete-optimizer

compilers/concrete-optimizer/concrete-optimizer/src/optimization/dag/multi_parameters/optimize/mod.rs

@@ -536,7 +536,7 @@ fn apply_fks_variance_and_cost_or_lower_bound(
         // if an optimized fks is applicable and is not to be optimized
         // we use the already optimized fks instead of a lower bound
         if let Some(this_fks) = initial_fks[src.0][dst.0] {
-            let to_be_optimized = fks_to_optimize[src.0].map_or(false, |fdst| dst == fdst);
+            let to_be_optimized = fks_to_optimize[src.0] == Some(dst);
             if !to_be_optimized {
                 if input_glwe == &this_fks.src_glwe_param && output_glwe == &this_fks.dst_glwe_param
                 {