allow GNUish macro assignments (`?=`, `+=`)

2 files changed, 37 insertions, 2 deletions

diff --git a/yapymake/makefile/__init__.py b/yapymake/makefile/__init__.py
index 52e2262..b5f96f1 100644
--- a/yapymake/makefile/__init__.py
+++ b/yapymake/makefile/__init__.py
@@ -196,23 +196,50 @@ class Makefile:
                 comment_split = value.split_once('#')
                 if comment_split is not None:
                     value, _ = comment_split
+                # GNU make allows for weird assignment operators
+                expand_value = False
+                skip_if_defined = False
+                append = False
+                if name_tokens.endswith('::'):
+                    self._warn('warning: non-POSIXful `::=` in macro')
+                    name_tokens.rstrip(':')
+                    expand_value = True
+                elif name_tokens.endswith(':'):
+                    self._warn('warning: non-POSIXful `:=` in macro')
+                    name_tokens.rstrip(':')
+                    expand_value = True
+                elif name_tokens.endswith('?'):
+                    self._warn('warning: non-POSIXful `?=` in macro')
+                    name_tokens.rstrip('?')
+                    skip_if_defined = True
+                elif name_tokens.endswith('+'):
+                    self._warn('warning: non-POSIXful `+=` in macro')
+                    name_tokens.rstrip('+')
+                    append = True
                 # > Any <blank> characters immediately before or after the <equals-sign> shall be ignored.
                 name_tokens.rstrip()
                 value.lstrip()
                 # > Macros in the string before the <equals-sign> in a macro definition shall be evaluated when the
                 # > macro assignment is made.
                 name = self.expand_macros(name_tokens)
+                if expand_value:
+                    value = TokenString.text(self.expand_macros(value))
                 # > Macros defined in the makefile(s) shall override macro definitions that occur before them in the
                 # > makefile(s) and macro definitions from source 4. If the -e option is not specified, macros defined
                 # > in the makefile(s) shall override macro definitions from source 3. Macros defined in the makefile(s)
                 # > shall not override macro definitions from source 1 or source 2.
                 if name in self._macros:
+                    if skip_if_defined:
+                        continue
                     source, _ = self._macros[name]
                     inviolate_sources = [MacroSource.CommandLine, MacroSource.MAKEFLAGS]
                     if self.args.environment_overrides:
                         inviolate_sources.append(MacroSource.Environment)
                     if any(x is source for x in inviolate_sources):
                         continue
+                if append and name in self._macros:
+                    _, old_value = self._macros[name]
+                    value = old_value.concat(TokenString.text(' ')).concat(value)
                 self._macros[name] = (MacroSource.File, value)
 
     def expand_macros(self, text: TokenString, current_target: Optional['Target'] = None) -> str:
diff --git a/yapymake/makefile/token.py b/yapymake/makefile/token.py
index 57ad4f9..d9ed5ac 100644
--- a/yapymake/makefile/token.py
+++ b/yapymake/makefile/token.py
@@ -54,12 +54,20 @@ class TokenString(Iterable['Token']):
             first_token.text = first_token.text.lstrip()
         self._tokens[0] = first_token
 
-    def rstrip(self) -> None:
+    def rstrip(self, chars: Optional[str] = None) -> None:
         last_token = self._tokens[-1]
         if isinstance(last_token, TextToken):
-            last_token.text = last_token.text.rstrip()
+            last_token.text = last_token.text.rstrip(chars)
         self._tokens[-1] = last_token
 
+    def endswith(self, pattern: str) -> bool:
+        last_token = self._tokens[-1]
+        return isinstance(last_token, TextToken) and last_token.text.endswith(pattern)
+
+    def concat(self, other: 'TokenString') -> 'TokenString':
+        return TokenString([*self._tokens, *other._tokens])
+
+
 @dataclass()
 class Token:
     pass