Add Github Problem Matchers actions for GCC/MSVC

MSVC needs two matchers: One general matcher for regular
single-line warnings, and one multi-line matcher for template
warnings that originate from a template in MSVC's library.

In the latter case, MSVC prints the path to the actual file
that should be annotated several lines down and all lines
in between the first line and that line need to be matched
by one of the regexps.

.github/problem-matchers/gcc.json

@@ -0,0 +1,17 @@
+{
+    "problemMatcher": [
+        {
+            "owner": "gcc-problem-matcher",
+            "pattern": [
+                {
+                    "regexp": "^(?:(?:\\.\\.?)?\\/)?(?:icinga2\\/)?(.*?):(\\d+):(\\d*):?\\s+(?:fatal\\s+)?(warning|error):\\s+(.*)$",
+                    "file": 1,
+                    "line": 2,
+                    "column": 3,
+                    "severity": 4,
+                    "message": 5
+                }
+            ]
+        }
+    ]
+}

.github/problem-matchers/msvc.json

@@ -0,0 +1,49 @@
+{
+    "problemMatcher": [
+        {
+            "owner": "msvc-problem-matcher",
+            "pattern": [
+                {
+                    "regexp": "^([^\\s].*icinga2.*)\\((\\d+),?(\\d+)?(?:,\\d+,\\d+)?\\):\\s(error|warning|info)\\s(\\w{1,2}\\d+):\\s([^\\s].*?)\\s\\[(.*)\\]$",
+                    "file": 1,
+                    "line": 2,
+                    "column": 3,
+                    "severity": 4,
+                    "code": 5,
+                    "message": 6,
+                    "fromPath": 7
+                }
+            ]
+        },
+        {
+            "owner": "msvc-template-problem-matcher",
+            "pattern": [
+                {
+                    "regexp": "^(?:[^\\s].*Microsoft.*)\\(\\d+,?\\d+?(?:,\\d+,\\d+)?\\):\\s(error|warning|info)\\s(\\w{1,2}\\d+):\\s([^\\s].*?)\\s\\[(.*)\\]$",
+                    "severity": 1,
+                    "code": 2,
+                    "message": 3,
+                    "fromPath": 4
+                },
+                {
+                    "regexp": "^\\s*(?:[^\\s].*Microsoft.*)\\(\\d+,?\\d+?(?:,\\d+,\\d+)?\\):.*$"
+                },
+                {
+                    "regexp": "^\\s*\\(compiling source file '.*?'\\)$"
+                },
+                {
+                    "regexp": "^\\s*(?:[^\\s].*Microsoft.*)\\(\\d+,?\\d+?(?:,\\d+,\\d+)?\\):.*$"
+                },
+                {
+                    "regexp": "^\\s+the template instantiation context \\(the oldest one first\\) is$"
+                },
+                {
+                    "regexp": "^\\s*([^\\s].*icinga2.*)\\((\\d+),?(\\d+)?(?:,\\d+,\\d+)?\\):$",
+                    "file": 1,
+                    "line": 2,
+                    "column": 3
+                }
+            ]
+        }
+    ]
+}

.github/workflows/linux.yml

@@ -69,6 +69,9 @@ jobs:
       - name: Checkout HEAD
         uses: actions/checkout@v5
 
+      - name: Turn on Problem Matcher
+        run: echo "::add-matcher::.github/problem-matchers/gcc.json"
+
       - name: Restore/backup ccache
         uses: actions/cache@v4
         with:

.github/workflows/windows.yml

@@ -38,6 +38,10 @@ jobs:
           Set-PSDebug -Trace 1
           & .\doc\win-dev.ps1
 
+      - name: Turn on Problem Matcher
+        run: |
+          Write-Host "::add-matcher::.github/problem-matchers/msvc.json"
+
       - name: Binary
         run: |
           Set-PSDebug -Trace 1