Switch fstring syntax to @..@ & limit fstring captures to int, str, float and bool

2 files changed, 8 insertions, 6 deletions

diff --git a/mesonbuild/interpreterbase.py b/mesonbuild/interpreterbase.py
index d486b89..93cd1c6 100644
--- a/mesonbuild/interpreterbase.py
+++ b/mesonbuild/interpreterbase.py
@@ -934,11 +934,15 @@ The result of this is undefined and will become a hard error in a future Meson r
         def replace(match: T.Match[str]) -> str:
             var = str(match.group(1))
             try:
-                return str(self.variables[var])
+                val = self.variables[var]
+                if not isinstance(val, (str, int, float, bool)):
+                    raise mesonlib.MesonException(f'Identifier {var} does not name a formattable variable.')
+
+                return str(val)
             except KeyError:
                 raise mesonlib.MesonException(f'Identifier "{var}" does not name a variable.')
 
-        return re.sub(r'{([_a-zA-Z][_0-9a-zA-Z]*)}', replace, node.value)
+        return re.sub(r'@([_a-zA-Z][_0-9a-zA-Z]*)@', replace, node.value)
 
     def evaluate_foreach(self, node: mparser.ForeachClauseNode) -> None:
         assert(isinstance(node, mparser.ForeachClauseNode))
diff --git a/test cases/common/238 fstrings/meson.build b/test cases/common/238 fstrings/meson.build
index ffee053..2db2649 100644
--- a/test cases/common/238 fstrings/meson.build
+++ b/test cases/common/238 fstrings/meson.build
@@ -2,8 +2,6 @@ project('meson-test', 'c')
 
 n = 10
 m = 'bar'
-s = f'test {n} string ({n}): {m}'
+s = f'test @n@ string (@@n@@): @m@'
 
-if s != 'test 10 string (10): bar'
-  error('Incorrect string formatting')
-endif
+assert(s == 'test 10 string (@10@): bar', 'Incorrect string formatting')