ci: key Windows sccache cache on MSVC version (#787)

## What
Add the `cl.exe` version to the Windows sccache cache key (and its
restore-keys prefix) in `test` and `sql_catalog_test`, so each MSVC
build keeps its own cache. On the `sql_catalog_test` matrix the suffix
stays empty for the non-Windows legs, so their keys don't change.

## Why
sccache decides whether a cached object is still valid from the compiler
binary. GitHub patches the Windows runner image regularly, roughly once
a week, and rolls each update out across the hosted fleet over a few
days rather than all at once. During that window back-to-back runs can
land on different `cl.exe` builds. When that happens the two builds
share one cache key and keep evicting each other, and a run on a newer
compiler restores the old cache, misses everything, and rebuilds the
whole stack (around 35 to 50 minutes). Putting the `cl.exe` version in
the key gives each compiler its own cache, so a run stays warm instead
of recompiling.

## Validation
On the `windows-2025` runner the resolve step read `cl.exe` as
19.51.36248, and the Windows `test` and `sql_catalog_test` builds passed
with the version in the key. The cache is only saved on `main`, so the
warm reuse shows up there rather than on a branch run.

Co-authored-by: Abanoub Doss <abanoub.doss@gmail.com>

Author: abnobdoss

.github/workflows/sql_catalog_test.yml

@@ -74,6 +74,26 @@ jobs:
         uses: ilammy/msvc-dev-cmd@0b201ec74fa43914dc39ae48a89fd1d8cb592756 # v1.13.0
         with:
           arch: x64
+      # GitHub patches the Windows image roughly weekly via gradual rollouts, so
+      # back-to-back runs can hit different cl.exe builds. sccache keys on the compiler,
+      # so a shared key would miss after each bump; the version keeps caches separate.
+      # Non-Windows legs get an empty suffix, leaving their keys unchanged.
+      - name: Resolve MSVC version for sccache key
+        if: ${{ startsWith(matrix.runs-on, 'windows') }}
+        shell: pwsh
+        run: |
+          $PSNativeCommandUseErrorActionPreference = $false
+          $banner = (cl.exe 2>&1 | Out-String)
+          if ($banner -match 'Version ([\d.]+)') {
+            $suffix = "-$($Matches[1])"
+          } else {
+            # The key is only a cache hint, so degrade to a shared bucket rather than
+            # fail the build; the warning flags that the parse needs fixing.
+            $suffix = '-unknown'
+            Write-Host "::warning::could not parse cl.exe version for sccache key, using '$suffix'; banner was: $banner"
+          }
+          Add-Content -Path $env:GITHUB_ENV -Value "SCCACHE_KEY_SUFFIX=$suffix"
+          Write-Host "SCCACHE_KEY_SUFFIX=$suffix"
       - name: Install dependencies on Ubuntu
         if: ${{ startsWith(matrix.runs-on, 'ubuntu') }}
         shell: bash
@@ -99,9 +119,9 @@ jobs:
         uses: actions/cache/restore@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5.0.5
         with:
           path: ${{ github.workspace }}/.sccache
-          key: sccache-sqlcatalog-${{ matrix.runs-on }}-${{ github.run_id }}
+          key: sccache-sqlcatalog-${{ matrix.runs-on }}${{ env.SCCACHE_KEY_SUFFIX }}-${{ github.run_id }}
           restore-keys: |
-            sccache-sqlcatalog-${{ matrix.runs-on }}-
+            sccache-sqlcatalog-${{ matrix.runs-on }}${{ env.SCCACHE_KEY_SUFFIX }}-
       - name: Setup sccache
         uses: mozilla-actions/sccache-action@9e7fa8a12102821edf02ca5dbea1acd0f89a2696 # v0.0.10
       - name: Configure Iceberg
@@ -129,7 +149,7 @@ jobs:
         uses: actions/cache/save@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5.0.5
         with:
           path: ${{ github.workspace }}/.sccache
-          key: sccache-sqlcatalog-${{ matrix.runs-on }}-${{ github.run_id }}
+          key: sccache-sqlcatalog-${{ matrix.runs-on }}${{ env.SCCACHE_KEY_SUFFIX }}-${{ github.run_id }}
       - name: Run SQL catalog tests
         shell: bash
         run: ctest --test-dir build -R '^sql_catalog_test$' --output-on-failure -C ${{ matrix.cmake_build_type }}

.github/workflows/test.yml

@@ -144,6 +144,24 @@ jobs:
         uses: ilammy/msvc-dev-cmd@0b201ec74fa43914dc39ae48a89fd1d8cb592756 # v1.13.0
         with:
           arch: x64
+      # GitHub patches the Windows image roughly weekly via gradual rollouts, so
+      # back-to-back runs can hit different cl.exe builds. sccache keys on the compiler,
+      # so a shared key would miss after each bump; the version keeps caches separate.
+      - name: Resolve MSVC version for sccache key
+        shell: pwsh
+        run: |
+          $PSNativeCommandUseErrorActionPreference = $false
+          $banner = (cl.exe 2>&1 | Out-String)
+          if ($banner -match 'Version ([\d.]+)') {
+            $msvc = $Matches[1]
+          } else {
+            # The key is only a cache hint, so degrade to a shared bucket rather than
+            # fail the build; the warning flags that the parse needs fixing.
+            $msvc = 'unknown'
+            Write-Host "::warning::could not parse cl.exe version for sccache key, using '$msvc'; banner was: $banner"
+          }
+          Add-Content -Path $env:GITHUB_ENV -Value "MSVC_VER=$msvc"
+          Write-Host "Resolved MSVC_VER=$msvc"
       - name: Cache vcpkg packages
         uses: actions/cache@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5.0.5
         id: vcpkg-cache
@@ -159,9 +177,9 @@ jobs:
         uses: actions/cache/restore@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5.0.5
         with:
           path: ${{ github.workspace }}/.sccache
-          key: sccache-test-windows-${{ github.run_id }}
+          key: sccache-test-windows-${{ env.MSVC_VER }}-${{ github.run_id }}
           restore-keys: |
-            sccache-test-windows-
+            sccache-test-windows-${{ env.MSVC_VER }}-
       - name: Setup sccache
         uses: mozilla-actions/sccache-action@9e7fa8a12102821edf02ca5dbea1acd0f89a2696 # v0.0.10
       - name: Build Iceberg
@@ -176,7 +194,7 @@ jobs:
         uses: actions/cache/save@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5.0.5
         with:
           path: ${{ github.workspace }}/.sccache
-          key: sccache-test-windows-${{ github.run_id }}
+          key: sccache-test-windows-${{ env.MSVC_VER }}-${{ github.run_id }}
       - name: Build Example
         shell: pwsh
         run: |