Merge branch 'master' into fix_fortran_fpic

CHANGES.txt

@@ -150,6 +150,10 @@ RELEASE  VERSION/DATE TO BE FILLED IN LATER
       file an error. It has issued a warning since 3.0, with "warn instead
       of fail" deprecated since 3.1.  Fixes #3958.
     - Minor (non-functional) cleanup of some tests, particuarly test/MSVC.
+    - Added more error handling while reading msvc config cache.
+      (Enabled/specified by SCONS_CACHE_MSVC_CONFIG).
+      The existing cache will be discarded if there's a decode error reading it.
+      It's possible there's a race condition creating this issue it in certain CI builds.
 
   From Jonathon Reinhart:
     - Fix another instance of `int main()` in CheckLib() causing failures

RELEASE.txt

@@ -103,7 +103,10 @@ FIXES
 - FORTRAN: Fix gfortran tool initialization. Defaults to using binary named gfortran 
   as would be expected, and properly set's SHFORTRAN flags to include -fPIC
   where previously it was only doing so for the other fortran versions (F77,..)
-
+- MSCommon: Added more error handling while reading msvc config cache.
+  (Enabled/specified by SCONS_CACHE_MSVC_CONFIG).
+  The existing cache will be discarded if there's a decode error reading it.
+  It's possible there's a race condition creating this issue it in certain CI builds.
 
 IMPROVEMENTS
 ------------

SCons/Tool/MSCommon/common.py

@@ -103,7 +103,7 @@ def debug(x, *args):
 
 
 # SCONS_CACHE_MSVC_CONFIG is public, and is documented.
-CONFIG_CACHE = os.environ.get('SCONS_CACHE_MSVC_CONFIG')
+CONFIG_CACHE = os.environ.get('SCONS_CACHE_MSVC_CONFIG', '')
 if CONFIG_CACHE in ('1', 'true', 'True'):
     CONFIG_CACHE = os.path.join(os.path.expanduser('~'), 'scons_msvc_cache.json')
 
@@ -113,50 +113,59 @@ def debug(x, *args):
     if os.environ.get('SCONS_CACHE_MSVC_FORCE_DEFAULTS') in ('1', 'true', 'True'):
         CONFIG_CACHE_FORCE_DEFAULT_ARGUMENTS = True
 
-def read_script_env_cache():
+def read_script_env_cache() -> dict:
     """ fetch cached msvc env vars if requested, else return empty dict """
     envcache = {}
-    if CONFIG_CACHE:
+    p = Path(CONFIG_CACHE)
+    if not CONFIG_CACHE or not p.is_file():
+        return envcache
+    with p.open('r') as f:
+        # Convert the list of cache entry dictionaries read from
+        # json to the cache dictionary. Reconstruct the cache key
+        # tuple from the key list written to json.
         try:
-            p = Path(CONFIG_CACHE)
-            with p.open('r') as f:
-                # Convert the list of cache entry dictionaries read from
-                # json to the cache dictionary. Reconstruct the cache key
-                # tuple from the key list written to json.
-                envcache_list = json.load(f)
-                if isinstance(envcache_list, list):
-                    envcache = {tuple(d['key']): d['data'] for d in envcache_list}
-                else:
-                    # don't fail if incompatible format, just proceed without it
-                    warn_msg = "Incompatible format for msvc cache file {}: file may be overwritten.".format(
-                        repr(CONFIG_CACHE)
-                    )
-                    SCons.Warnings.warn(MSVCCacheInvalidWarning, warn_msg)
-                    debug(warn_msg)
-        except FileNotFoundError:
-            # don't fail if no cache file, just proceed without it
-            pass
+            envcache_list = json.load(f)
+        except json.JSONDecodeError:
+            # If we couldn't decode it, it could be corrupt. Toss.
+            with suppress(FileNotFoundError):
+                p.unlink()
+            warn_msg = "Could not decode msvc cache file %s: dropping."
+            SCons.Warnings.warn(MSVCCacheInvalidWarning, warn_msg % CONFIG_CACHE)
+            debug(warn_msg, CONFIG_CACHE)
+        else:
+            if isinstance(envcache_list, list):
+                envcache = {tuple(d['key']): d['data'] for d in envcache_list}
+            else:
+                # don't fail if incompatible format, just proceed without it
+                warn_msg = "Incompatible format for msvc cache file %s: file may be overwritten."
+                SCons.Warnings.warn(MSVCCacheInvalidWarning, warn_msg % CONFIG_CACHE)
+                debug(warn_msg, CONFIG_CACHE)
+
     return envcache
 
 
 def write_script_env_cache(cache) -> None:
     """ write out cache of msvc env vars if requested """
-    if CONFIG_CACHE:
-        try:
-            p = Path(CONFIG_CACHE)
-            with p.open('w') as f:
-                # Convert the cache dictionary to a list of cache entry
-                # dictionaries. The cache key is converted from a tuple to
-                # a list for compatibility with json.
-                envcache_list = [{'key': list(key), 'data': data} for key, data in cache.items()]
-                json.dump(envcache_list, f, indent=2)
-        except TypeError:
-            # data can't serialize to json, don't leave partial file
-            with suppress(FileNotFoundError):
-                p.unlink()
-        except OSError:
-            # can't write the file, just skip
-            pass
+    if not CONFIG_CACHE:
+        return
+
+    p = Path(CONFIG_CACHE)
+    try:
+        with p.open('w') as f:
+            # Convert the cache dictionary to a list of cache entry
+            # dictionaries. The cache key is converted from a tuple to
+            # a list for compatibility with json.
+            envcache_list = [{'key': list(key), 'data': data} for key, data in cache.items()]
+            json.dump(envcache_list, f, indent=2)
+    except TypeError:
+        # data can't serialize to json, don't leave partial file
+        with suppress(FileNotFoundError):
+            p.unlink()
+    except OSError:
+        # can't write the file, just skip
+        pass
+
+    return
 
 
 _is_win64 = None
@@ -381,7 +390,7 @@ def parse_output(output, keep=KEEPLIST):
     # rdk will  keep the regex to match the .bat file output line starts
     rdk = {}
     for i in keep:
-        rdk[i] = re.compile('%s=(.*)' % i, re.I)
+        rdk[i] = re.compile(r'%s=(.*)' % i, re.I)
 
     def add_env(rmatch, key, dkeep=dkeep) -> None:
         path_list = rmatch.group(1).split(os.pathsep)